Presentation Message … Theme 1

Presentation Message … Theme 1
The Forecast Cycle Analysis Diagnosis Prognosis Verifinosis You are the most important part of the Forecast Cycle Take the Forecast Cycle for a Spin Human Skills ………. Pattern Recognition Conceptual Models Anticipation versus reaction

Presentation Message … Theme 2
Remote Sensing is your Friend Fantastic Time & Space Resolution Animation Today’s Topic You may want to see a tornado before you die but not just before you die! Satellite and radar meteorology are his personal favourites. For Real Time A&D The actual atmosphere is the best tool and teacher… For Lead Time

Cartoonist is confused between radar and satellite technologies
The Satellite Palette and The Radar Palette addresses this…see NorLat and COMET websites

For God's sake, we had to wait 25 years for Doppler… I pray it won't be that long to get Dual Polarized!

Notice how each of the angels have their own radar system above their heads. I think they are only conventional systems though showing strictly reflectivity data. Together, all of the angels form a composite radar picture of heaven only knows...

Doppler radar shows moisture confluence throughout the Celestial dome but let's take a look at our Dual Polarized data … to diagnosis the characteristics of those hydrometeors

Doppler radar. God only knows what it means
Doppler radar? God only knows what it means! We will all know after we take the MSC Radar Course though.

Doppler (Droppler) radar shows that we are in the positively buoyant, backing winds area of the warm conveyor belt to the left of the Screaming Eagle.

Doppler Patterns - Outline
Doppler Basics Doppler Signatures Basic Signatures Wind Analysis (Meso and Synoptic Flows) Advanced Signatures Atmospheric Diagnosis (VWS, Stability, Trends in both) Conveyor Belt Conceptual Model (CBCM) Summary I would like the participants to have access to this presentation so that they can play it again at their own leisure. There is a lot of information here. This first presentation cannot make you an expert although it is intended to encourage you to practice. The “hidden” slides are important but had to be cut to make it even remotely possible to achieve the time limit allotted to this presentation. Within this presentation there is a strong emphasis on operational conceptual models and how Doppler radar might be used to assess which conceptual model best applies in a particular situation. As a result there is significant effort made to describe and explain the relevance of each conceptual model. As a result this presentation does not simply display multiple examples of Doppler radar imagery. It is intended to be much more. I hope that you enjoy it. You will notice an “end” link in the lower right hand corner of the last several pages. This link will allow me to jump to the end and wrap up the presentation should we run out of time. It is more important to cover the material well than to cover it all poorly. The underlying theme of this presentation is that the human meteorologist is the most important part of the forecast cycle. Using artistic pattern recognition skills and exercising sound scientific judgment to provide a professional service Phil Chadwick Biography Phil Chadwick is an operational meteorologist turned researcher and instructor. Phil the Forecaster has been a meteorologist with Environment Canada since The last five years associated with COMET, have been a career highlight. Phil specializes in the analysis and diagnosis of severe weather using remote sensing (one doesn't want to get too close). You may want to see a tornado before you die but not just before you die! Satellite and radar meteorology are his personal favourites. Phil’s research includes extensive papers on performance measurement and severe weather climatology, Visual Basic programming and of course, remote sensing. Most of this research can be found on the NorLat website under “case studies”. Simply Google “NorLat”. Phil is first and foremost an operational meteorologist who believes that the analysis and diagnosis of the real atmosphere is an important way to advance the science. Admittedly, Phil has concentrated on satellite meteorology and has been branded as a satellite meteorologist throughout his career. Radar meteorology is very important as well but there is always satellite data available at great spatial and temporal resolutions to bring to bear on the analysis and diagnosis concern of the day – the “problem du jour”. Some of Phil’s radar meteorology applications appear for the first time in this radar course. Finally, Phil strongly believes that meteorology and science must be fun and that the human has an important if not essentially vital role in the provision of quality service. Many of the following signatures will only be evident in Doppler – Clouds obscures the low level, precipitating signatures in Satellite Imagery.

Doppler Patterns Analysis and Diagnosis for All Seasons
The Doppler Mantra ‘Look for Something “Odd”’ “Look UP ” Background: Login: MetEd login followed by a prompt to enter an enrollment key for the course: mscradar Presentation: the stage 2 of the Radar Course. Show: this is your portion of the course, to show the students how to integrate the radar information into their daily routines, to show them the potential inherent in using the radar. Note that stage 1 is the Inform Stage: give the students the basic information they are going to need to complete the course and stage 3 is the Do Stage: the residence course is where we'll give the students the time to actually do the integration of the radar techniques that they learned with all the other data sources at their disposal to write forecasts. This will be done by looking at live cases, where possible, and failing that, canned ones. Presentation Details: This presentation is slated for 60 minutes. As revealed during our testing of the on-line presentations, animations will be limited. Any dynamic part of the presentation will be restricted to what can be incorporated within a PowerPoint presentation. I will focus on the application of Doppler radar information using conceptual models. My intent is to: First explain the conceptual model emphasizing the meteorological importance of the information; Highlight the Doppler signatures that are characteristic of the conceptual model; Apply the conceptual model to an operational case demonstrating how the use of the Doppler radar was key in the correct analysis and diagnosis of the meteorological information. Apply the conceptual model to a second independent operational case demonstrating possible differences in the Doppler radar signatures. The conceptual models I plan to discuss are all selected from the Radar Palette. In light of the brief 60 minute period and the importance of warm frontal precipitation, I will focus on the warm frontal portion of the mid-latitude cyclone conveyor belt conceptual model. Many of these conceptual models will be new to the participants. Of course we give thanks to Johann Christian Doppler, the Austrian physicist who first related observed frequency changes in sound and light to motion of the source or observer in The change in frequency = Doppler shift, fd fd = -2 Vr/λ or fd = -2(Vr/c)f The emitted energy is absorbed, then re-emitted by target. The radar receives the re-emitted energy and if the target is moving, frequency of returned radiation intercepted by a radar will be changed. The Doppler effect is used in weather radars primarily to measure the velocity of detected objects and to remove clutter. Doppler weather radar measures the Phase Shift between the emitted and received signal

What You Know from Part 1 of the Radar Course
The Doppler Effect and Shift Doppler Weather Radar Velocity Determination Signal Processing Limitations More on Velocity Aliasing Solving the Doppler Dilemma PPI Displays of Raw Doppler Data of Radial Wind Determining Wind Direction Wind Profiles Vertical Profiles Broadscale Flows Mesoscale Flows Dave Ball, the Director of this Course has provided all of the above information in various formats using various methods. This is important information but one will only realize why it is so vital when you start to actually use it. We will illustrate how one uses Doppler radar in an operational setting during this “show” presentation.

Doppler Radar Quantities – The Data
Backscattered power (R) equivalent reflectivity factor and estimates of the precipitation rate Mean radial velocity (V) Spectral width of radial velocity of targets within the sample volume (W) Mean Radial V Spectral Width Integral of S(v) over V R= Doppler radar measures: the power backscattered by targets which are intercepted by the radar beam. From these measurements the equivalent reflectivity factor and estimates of the precipitation rate can be derived. the mean radial velocity and spectral width of radial velocity of targets within the sample volume. These are the Doppler radar quantities which we can use to analyze the characteristics of a meteorological situation in an effort to identify the most appropriate and applicable conceptual model. It was shown that the backscattered power is strongly dependent on drop size. The strength and phase of the received signal is therefore largely determined by the density of larger drops in the sample volume even though these might be much less numerous. Fortunately the larger drops will tend to move with the mean flow within the sample volume and will be much less effected by small scale turbulent flow in comparison to the very small drops. Measuring the Doppler velocity of these drops will therefore provide a good estimate of the mean wind. Note that Doppler radars only measure the radial component of velocity (because they only measure the change in the target’s range) The transverse component of velocity is not sensed, so the total velocity of the target is unknown. Phased Doppler arrays circumvent this deficiency although they are fairly rare in the world. Velocity Aliasing. All such solutions which satisfy the measured phases are known as aliases. The phase shift measured by the radar is ambiguous to within multiples of 2π and consequently, the velocity calculated by the radar is ambiguous to within multiples of λ/2T meaning that the radar cannot distinguish between velocity v from velocity v + (λ/2T). The trade off between velocity aliasing and range folding which must be made when selecting an operating PRF for a Doppler radar is termed the “Doppler dilemma”. The selection of a 10 cm radar with its inherent additional cost can overcome some of the problem if both long range and high Nyquist velocity is required.

Spectral Width and “Doppler Display Texture”
Rain Doppler Texture Rain has a broad spectral width due to a broad range in fall rates. Rain can fall up to 10 metres per second although much depends on drop size. Snow has a relatively narrow spectral width due to a small range in fall rates near 1 metre per second. Snow Doppler Texture

Velocity Azimuth Display - VAD
At a given height (h), then the radial velocity is: Vr For a uniform flow field, assume Vw (Vertical Velocity) approximately = 0 Best fit of a sine curve to the observations around the circle. Maximum Inbound Maximum Outbound Velocity Azimuth Display - VAD Maximum Outbound No Radial Maximum Inbound

Velocity Azimuth Display - VAD
VAD accuracy decreases with elevation angle and height. The desired horizontal wind component becomes a smaller part of the radial wind component actually measured. Errors in the radial component has a bigger impact on the accuracy of the horizontal wind Variation in the Doppler velocity are pronounced at the higher elevations as it shoots through the precipitation. VAD accuracy decreases with elevation angle and height. The desired horizontal wind component becomes a smaller part of the radial wind component actually measured. Errors in the radial component has a bigger impact on the accuracy of the horizontal wind Variation in the Doppler velocity are pronounced at the higher elevation angles. The above example also looks as though the radar is punching through the top of the layer of precipitation.

Doppler Wind Shifts – Viewing Angles
B A The angle of viewing is very important and determines what one sees! Viewing angles are very important.

Doppler Radar Analysis and Diagnosis Quantities
Determining the Horizontal Winds Curvature Confluence Wind Shear VWS Trends Thermal Advections Trends in time/space Stability Stability Trends Doppler Texture and Spectral Width Precip Phase Doppler Data and Viewing Angle Limitiations These are the Doppler radar quantities which we can use to analyze the characteristics of a meteorological situation in an effort to identify the most appropriate and applicable conceptual model. Some principles for “smooth” flows: Colour coding indicates whether radial velocities are inbound or outbound The “zero isodop” (ZI) separates regions of inbound and outbound radial velocities. Along the ZI the total wind is either tangential or zero With increasing range radar samples flow at higher and higher altitudes. The zero isodop is a line connecting points of zero radial velocity and is a key feature visible on most Doppler velocity images. It separates a region of inbound velocity from a region of outbound velocity and passes through the origin (the radar). Note: I am using examples that the participants should already be very familiar with. We will build a bridge from this familiar content to more complex material that they are not familiar with! Know the limitations of the data…

Doppler Radar Analysis and Diagnosis Quantities
Determining the Horizontal Winds Curvature Confluence Wind Shear VWS Trends Thermal Advections Trends in time/space Stability Stability Trends Doppler Texture and Spectral Width Precip Phase These are the Doppler radar quantities which we can use to analyze the characteristics of a meteorological situation in an effort to identify the most appropriate and applicable conceptual model. Some principles for “smooth” flows: Colour coding indicates whether radial velocities are inbound or outbound The “zero isodop” (ZI) separates regions of inbound and outbound radial velocities. Along the ZI the total wind is either tangential or zero With increasing range radar samples flow at higher and higher altitudes. The zero isodop is a line connecting points of zero radial velocity and is a key feature visible on most Doppler velocity images. It separates a region of inbound velocity from a region of outbound velocity and passes through the origin (the radar). Note: I am using examples that the participants should already be very familiar with. We will build a bridge from this familiar content to more complex material that they are not familiar with! Know the limitations of the data…

Horizontal Wind Determination
Max/Min Method Comes in … Goes out Caution: Not all flows are uniform Important flows not uniform Determining Wind Direction Max/Min Method Identify maximum inbound and/or maximum outbound velocity at range/elevation of interest These should be about +/- 90 degrees from the zero isodop

Horizontal Wind Determination
Zero Isodop Method Comes in … Goes out Caution: Think the pattern through Deduces important non- uniform flows The determination of the wind direction using Doppler radar is key to the Radar Course and thus a quick review is in order. Zero Isodop Method Identify the zero isodop (ZI) At any point on the zero isodop Draw a radial from the radar to the point At the point draw an arrow perpendicular to radial Point the arrow from inbound to outbound This is the wind direction at that location in space Method: Draw Radial from radar Wind perpendicular to radial Pointing toward warm The Purple Vectors Have ZERO radial Component – Not measured. Isodop Method reveals details!

Doppler Wind Signatures
Constant Direction and Speed Comes in … Goes out Constant Direction But Speed Increases With Height (Range) What goes in, goes out by the law of continuity. Comes in … Goes out

Constant Direction But Speed Maximum Horizontal Flow Comes in … Goes out Constant Direction But Ascending Speed Maximum What goes in, goes out by the law of continuity. Comes in …Goes out

Diffluence Continuity requires ascent from below Confluence What goes in, goes out by the law of continuity. Continuity requires descent to below

Backing Counter-clockwise Isodop With Height Cold Advection Veering Clockwise Isodop With Height What goes in, goes out by the law of continuity. Warm Advection Wind normal to Isodop and Isodop relative to its starting orientation

Doppler Wind Signatures - Doppler Vortex
‘Look for Something “Odd”’ Broad Scale Flow Rotating flows are not uncommon in the atmosphere, so it is useful to recognize how they may appear. At the smallest scale a vortex might be a mesocyclone associated with tornadic storm. At the larger scale a vortex might be the flow around a low pressure centre. Figure 6:Small embedded vortex. Figure 6. shows a 10km wide vortex rotating in solid body rotation added to a field with uniform motion of 5m/s.

Doppler Wind Signatures - Doppler Downburst
‘Look for Something “Odd”’ Higher… The divergent signature is southeast of the radar and is too large (more than 4 km in diameter) to be classified as a microburst. This particular example is that of a macroburst. The term is either a macroburst or downburst. Corresponding Radial Velocity Images. Note that at the higher elevation angles a rotation signature can be seen. Downbursts are often observed with rotation during its descent. Doppler Radial diffluence Doppler Radial confluence…

Doppler Wind Shear Zero Isodop Method
Winds Back with height = VWS = Cold advection Zero Isodop Method Back Back Isodop Arc backs or is counter-clockwise with height/range Cold VWS Cold Advection (relative to radar) Determining Wind Shear Zero Isodop Method Identify the zero isodop (ZI) At any point on the zero isodop Draw a radial from the radar to the point At the point draw an arrow perpendicular to radial Point the arrow from inbound to outbound This is the wind direction at that location in space

Think in 3-D Doppler Wind Shear “look for something odd”
Winds Veer with height = VWS = Warm advection Veer Veer Wind speed at a given height (slant range) is determined by the extreme Doppler velocity values around a constant slant range circle (as displayed in Fig ). In the Figure, the maximum flow away from the radar (light orange) and the maximum flow toward the radar (light blue) is the same from the center out to the edge of the display, indicating that the wind speed is constant (between 25 and 30 m s-1) from the ground to the height corresponding to the edge of the display. Thus the Doppler velocity pattern in the Figure uniquely represents an environmental wind profile where wind speed is constant and wind direction veers uniformly from southerly at the ground through southwesterly to westerly at the edge of the display. There were many classic Doppler radar patterns shown in the Radar Course notes. These classic examples do exist in the natural world but the focus of this presentation is to feature the real atmosphere. I will not use them here except to illustrate the following main points to consider in analyzing Doppler radar: The Doppler radar mantra “look for something odd” Oddities following along range rings are vertical discontinuities Oddities following along radials are horizontal discontinuities Isodop Arc veers or is clockwise with height/range Warm VWS Warm Advection (relative to radar) Think in 3-D

Vertical Discontinuities
“look for something odd” follow a range ring for vertical discontinuities SW - Level SE - Level SW - Level Patterns Associated with Vertical Discontinuities in the Wind Field Figures and illustrate examples of Doppler velocity fields that pass through a horizontal surface that separates two different atmospheric flow regimes. It is assumed that there is a wind speed maximum within each wind regime and that the wind directions differ by 90° or 180°, respectively, across the discontinuity. The discontinuity could represent a frontal surface or it could represent the top of the boundary layer in clear air. Note the variation of the zero Doppler velocity line in Fig It is oriented northeast-southwest through the center of the display indicating a constant wind direction in the lower layer. The inner pair of bull’s eyes indicates that the wind is blowing from the southeast to northwest at a maximum speed of 25–30 m s-1 (49–58 kt). The zero velocity line indicates a 90° shift in wind direction through a narrow height interval, with the wind direction becoming constant again above the discontinuity. The second pair of bull’s eyes indicates that the upper layer winds are from the southwest at a maximum speed of 25–30 m s-1 (49–58 kt). The wind shift through the discontinuity is much more dramatic in Fig than in Fig The orientation of the zero Doppler velocity line and the locations of the positive and negative Doppler velocity extremes indicate easterly winds in the lower layer capped by westerly winds aloft.

Horizontal Discontinuities
“look for something odd” follow a radial looking for discontinuities that do NOT follow along a range ring… NW – Level ? SW - Level ? 7 Patterns Associated with Horizontal Discontinuities in the Wind Field With adequate radar return, it is possible to determine characteristics of the flow field both ahead of and behind a horizontal discontinuity (such as a front, outflow boundary, wind shift line). Figures 2.7.1–2.7.3 clearly indicate that the discontinuity is marked by a rapid change of Doppler velocity values over a narrower transition region. The sequence of three figures shows the movement of the discontinuity approaching from the northwest, located over the radar, and finally moving away from the radar toward the southeast. Winds ahead of the discontinuity essentially are from the southwest and those behind the discontinuity essentially are from the northwest. Different wind profiles are used in each figure. The variation in wind vectors is due to the change of wind with height. In Fig , wind direction is constant on both sides of the discontinuity and wind speed is a maximum in the middle of the height interval (as in Fig ). Wind direction is constant on both sides of the discontinuity in Fig , but wind speed increases linearly from the ground to the edge of the display (as in Fig ). In Fig , wind speed increases with height from zero at the ground while wind direction veers ahead of the discontinuity (similar to Fig ) and backs behind it.

The Doppler Texture is smooth. What is it?
10 Hail Freezing Rain Rain Snow

The Doppler Texture is smooth. What is it?
Hail Freezing Rain Rain Snow

The Doppler shows an area of zero velocity. What does it mean?
10 There is no wind. The wind is parallel to the radar beam. The wind is perpendicular to the radar beam. There is no precipitation. Perpendicular

The Doppler shows an area of zero velocity. What does it mean?
There is no wind. The wind is parallel to the radar beam. The wind is perpendicular to the radar beam. There is no precipitation. Perpendicular

Divergence/Convergence Rotation Anomalous Propagation Birds/Insects
Doppler shows red and blue areas separated by a short distance along a range ring. What is it? 10 Divergence/Convergence Rotation Anomalous Propagation Birds/Insects

Doppler shows red and blue areas separated by a short distance along a range ring. What is it?
Divergence/Convergence Rotation Anomalous Propagation Birds/Insects

Convergence/divergence Rotation Anomalous Propagation Birds/Insects
Doppler shows red and blue areas separated by a short distance along a radar radial. What is it? 10 Convergence/divergence Rotation Anomalous Propagation Birds/Insects

Doppler shows red and blue areas separated by a short distance along a radar radial. What is it?
Convergence/divergence Rotation Anomalous Propagation Birds/Insects

Doppler Patterns Analysis and Diagnosis for All Seasons
The Doppler Mantra ‘Look for Something “Odd”’ “Look UP ” ‘Look for Something “Odd”’ is no the entire story. Not the whole truth. There are millions of stars in the night sky but which ones are “odd”? A big part of meteorology is to learn what is “odd” in the remote sensing data. What is “odd” is also important.

Doppler Analysis and Diagnosis - Steps
Find the origin – home base Follow one isodop branch out and up (depends on elevation angle) Oddity = change in angle with respect to the range rings – larger angle = larger significance Oddity = inflection point marking change of direction Repeat for other isodop branch Match oddities in height Infer spatial slopes Invoke conceptual models Determine the four winds Something that is difficult to find is probably not worth finding Process takes less than 5 minutes Situational Awareness Repeat as required Add water and stir briskly… Think 3D! My message: Humans have pattern recognition skills hones before birth. They skills are way beyond any computer! These skills allows homo sapien to crawl from the cave. Computer models are a tool like a club and not the solution. This may not be a popular view. I am convinced that storm by storm performance measurement would reveal the true and positive impacts of the meteorologist in the provision of service. Meteorologists need: Animated display of real (remote sensing) data – current solution is NinJo Conceptual models within which to place these patterns – the Satellite and Radar Palettes A management and operational structure to supply and promote requirements one and two What gets rewarded, gets done. Excellence in operational, meteorological service has not been typically rewarded and I can supply many examples that such is the case. MSC could be so much more than it is which is truly sad. Pattern recognition skills Animated real data Conceptual Models (Satellite/Radar Palettes) What gets rewarded, gets done…

Conventional Analysis and Diagnosis - Steps
Not so focused Lots of possible interpretations for features both in space and height and time Must employ the conceptual models of the many artefacts and many meteorological features Situational awareness is critical for success Process takes less than 5 minutes Repeat as required Add water and stir briskly… Think 3D My message: Humans have pattern recognition skills hones before birth. They skills are way beyond any computer! These skills allows homo sapien to crawl from the cave. Computer models are a tool like a club and not the solution. This may not be a popular view. I am convinced that storm by storm performance measurement would reveal the true and positive impacts of the meteorologist in the provision of service. Meteorologists need: Animated display of real (remote sensing) data – current solution is NinJo Conceptual models within which to place these patterns – the Satellite and Radar Palettes A management and operational structure to supply and promote requirements one and two What gets rewarded, gets done. Excellence in operational, meteorological service has not been typically rewarded and I can supply many examples that such is the case. MSC could be so much more than it is which is truly sad.

What are the implications for vertical stability?
Doppler Practice Black range ring separates Veering Isodop from Backing Isodop “look for something odd” Cooling Warming Doppler Practice Low Level Veering Under High Level Backing What are the implications for vertical stability?

Doppler Practice ‘Look for Something “Odd”’ SWLY NNELY LLJ
Vertical NNELY LLJ QS Horizontal LLJ Doppler Practice Winds Backing with Height - Cold Air Advection Cold Conveyor Belt ahead of a synoptic system… Horizontal or Vertical Discontinuity? Cold front with surface discontinuity to the southeast. March 93 – the storm of the century! Snow Texture!

Doppler Wind Analysis – More Practice
Isodop Wind Analysis Follow isodop outward Draw line from radar Wind is perpendicular to this radial, towards the red echoes Doppler Practice

Doppler Wind Analysis – More Practice
For any height you can determine the wind in four locations Determine the two isodop winds For the maximum winds look roughly 90° away from the isodop winds The wind maxs are where the winds align along a radial Full wind toward radar Full wind away from radar Analyze areas of non-uniform flow curvature from direction confluence from speed More Practice Further, there is a marked discontinuity following a range ring which implies a large discontinuity in wind direction in the vertical. Let’s analyze this. At 5.3 km … Anticyclonic Ridge with mass confluence Subsidence below. Nil pcpn above. What’s your short range forecast?

Doppler Wind Analysis – Even More Practice
Range Ring Discontinuity - Difference in the Vertical Below Discontinuity NLY winds veering 30o with height Warm advection Max wind rising a lot ACYC curvature No sig confluence ….23kts in 23kts out…. 23 Isodop Discontinuity Veers clockwise Warm front 23 Above Discontinuity SLY winds nil directional shear Nil thermal advections ACYC curvature Mass confluence …60kts in only 45kts out.. More Practice Further, there is a marked discontinuity following a range ring which implies a large discontinuity in wind direction in the vertical. Let’s analyze this. You have to follow a radial through the radar to get a sense of the slope of the discontinuity thorough the radar. Discontinuity Slope 2.4 km SE rising to 2.8km NW 2.7 km S steady to 2.7 N Synoptic Situation … Zonal frontal zone with stable waves Warm front slanted toward the NNW. Subsidence below. but strong Cold Conveyor Belt – nil motion

The location of the max inbound and max outbound reveals flow:
10 Curvature Convergence/divergence Ascent/descent All of the above None of the above

The location of the max inbound and max outbound reveals flow:
Curvature Convergence/divergence Ascent/descent All of the above None of the above

VWS Diagnosis VWS Isodop Method
B C D = VWS Inflection Determine wind at B. Draw radial from radar site A to the isodop at B. Determine wind at C. Wind backs from B to C. Relative to A the isodop backs or turns counter-clockwise. Determine wind at D. Wind veers from C to D. Relative to A the isodop veers or turns clockwise. A Summary Thermal Advection Intensity The larger the angle subtended by the arc, the larger the wind shift and stronger the thermal advections. This wind shift/angle independent of range from radar Thermal Advection Type – Relative to Radar Site If isodop turns counter-clockwise with height (increasing range), arc associated with cold advection… winds back with height. If isodop turns clockwise with height (increasing range), arc associated with warm advection… winds veer with height. The VWS inflection at the limiting radial marks the range/height separating backing and veering portions of the isodop. Thermal Advection Intensity The larger the angle subtended by the arc, the stronger the advections. The smaller the angle subtended by the arc, the weaker the advections. Thermal Advection Type If the arc rotates cyclonically or clockwise with height, the arc is associated with warm thermal advection. If the arc rotates anticyclonically or counterclockwise with height, the arc is associated with cold thermal advection. … and yes, I made this up – maybe even invented it for the first time. Who knows? Phil

Diagnosis of VWS – Using the Isodop
B C D A B C D A Angle subtended by the counter-clockwise isodop BC would be the same regardless of the exact location of C anywhere along the radial AC from the Doppler radar. The amount of wind shear (cold) is dependent only on the subtended angle and not the orientation of the arc. The amount of wind shear (warm) is dependent only on the subtended angle and not the orientation of the arc. Thermal Advection Intensity The larger the angle subtended by the arc, the stronger the advections. The smaller the angle subtended by the arc, the weaker the advections. Thermal Advection Type If the arc rotates cyclonically or clockwise with height, the arc is associated with warm thermal advection. If the arc rotates anticyclonically or counterclockwise with height, the arc is associated with cold thermal advection. … and yes, I made this up – maybe even invented it for the first time. Who knows? Phil Thermal VWS is thus the angle subtended by the isodop divided by the elevation change that this thermal advection occurred over. The following slide illustrates these concepts.

Thermal Advections and VWS
Angle subtended by the counter-clockwise isodop BC is identical in 1, 2 and 3. In 1, winds back over a short radial range Radial range & height difference increases for 2 Radial range difference is even more for 3 Height interval for the Thermal VWS increases with the length of the radial DC from case 1 to 3 Thermal VWS determined by dividing the directional shear (isodop angle) by the height interval (Difference between AC and AD=DC): Strongest for 1 Moderate for 2 Weakest for 3. Thermal VWS is proportional to the size of the subtended angle divided by the radial range (AC-AD=DC) which is inversely proportional to area BCD D C 1. A B A B C D 2. A B C ~1/Small Area ~1/Medium Area Radial ~1/Large Area Thermal Advections and VWS D Isodop 3. Range Ring WS Isodop Angle 1 VWS = = ~ Depth Radial Height Change Isodop Area (BCD)

Given these isodops, which has the strongest thermal advection?
Nearly along a range ring At a significant angle to the range ring Nearly along a radial 10 A 1. 2. 3.

Given these isodops, which has the strongest Thermal VWS? D C 1. A For a given isodop subtended angle, the smaller the area CBD, the smaller the height interval, the more intense the thermal advections. Strongest Thermal VWS occurs with a isodop closely following the range rings Weakest Thermal VWS occurs with a isodop closely following the radar radial lines B C D 2. A B C Thermal Advections and VWS D 3. A B

Given these isodops , which has the strongest Thermal VWS? C 1. A For a given isodop height interval radial: Strongest Thermal VWS occurs with the largest subtended angle Weakest Thermal VWS occurs with the smallest subtended angle B A B C 2. A B C Thermal Advections and VWS 3.

Doppler Isodops for Increasing ?
Stability D Level D Weaker cold advection CD Level C Stabilization Stronger cold advection BC C Level B 1. Backing Wind Turning Along the Radial A B Level D Stronger warm advection CD C Level C Stabilization B Weaker warm advection BC Level B 2. A Veering Wind Turning Along the Rings D Level D Making the most of Doppler Isodops (Strong) Warm advection CD C Level C Stabilization (Weak) Cold advection BC Level B 3. A D B Note: Angles kept constant. Changing the Thermal Advection Intensity by changing the depth of the directional wind shear.

Isodop Diagnosis of Stabilization Trends
Stability increases with: Cold advection decreasing with height: Angle of backing Doppler isodop veers to become more aligned along a radial, Warm advection increasing with height: Angle of veering Doppler isodop veers to become more aligned along the range rings, Cold advection under warm advection: Doppler isodop backing counterclockwise with height (range) under Doppler isodop veering clockwise with height (range). Following the Isodop – for Stabilization A B C A B C D A B C D Making the most of Doppler Isodops Using the zero line to establish wind shear: For a fixed length of arc, if the wind shear is aligned along a range ring (spatial distribution of wind shear), then it is likely that the same wind shear is also experienced in the short vertical distance. Strong wind shear over a short vertical distance is associated with strong thermal advections. For a fixed length of arc, if the wind shear is aligned along a radar radial (vertical distribution of wind shear), then it is certain that the wind shear is also experienced in the larger vertical distance. Strong wind shear spread over a larger vertical distance is associated with weaker thermal advections. The conceptual model summary for this is that thermal advections should generally decrease as the angle between the range ring and the arc (zero line) increases. Of course, the exact amount of wind shear can probably be determined by making the best estimate of the actual winds and wind shear from the colour display. This approach would take longer and not be used operationally. Remember: Veering with Height = Warming with Height = Stabilization (Red = Stop) Cold Advection - Backing Veers Warm Advection - Veering Veers Important Generalization: For Stabilization isodop veers with height/range

Instability D Level D Stronger cold advection CD Level C Destabilization C Weaker cold advection BC Level B 1. Backing Wind Turning Along the Rings A B Level D B Weaker warm advection CD C Level C Destabilization Stronger warm advection BC D A Level B 2. Veering Wind Turning Along the Radial D Making the most of Doppler Isodops Level D (Weak) Cold advection CD Destabilization B Level C C (Strong) Warm advection BC Level B 3. A Note: Angles kept constant for simplicity. Changing the Thermal Advection Intensity by changing the depth of the directional wind shear.

Isodop Diagnosis of Destabilization Trends
Stability decreases (Destabilization) with: Cold advection increasing with height: Angle of backing Doppler isodop backs to become more aligned along the range rings Warm advection decreasing with height: Angle of veering Doppler isodop backing to become more aligned along a radial, Warm advection under cold advection: Doppler isodop veering clockwise with height (range) under Doppler isodop backing counterclockwise with height (range). Following the Isodop – for Destabilization A B C D A B C D A B C D Making the most of Doppler Isodops Remember: Backing with Height = Cooling with Height = Destabilization (Green = GO) Cold Advection - Backing backs Warm Advection - Veering backs Important Generalization: For Destabilization Isodop backs with height/range

Changing Stability by Changing the Angle of the VWS
As angle subtended by isodop increases, the amount of directional wind shear also increases. The directional wind shear must be divided by the height over which this shear occurs in able to determine the magnitude of the thermal advections. Generally, as the angle increases, so does the thermal advections. The angle of the isodop relative to the range rings is an essential technique in an operational setting. Isodop backing relative to its starting orientation for destabilization Isodop veering relative to its starting orientation for stabilization

Stability D Level D Weaker cold advection CD C Level C Stabilization Stronger cold advection BC Level B 1. A B Level D Stronger warm advection CD C Stabilization B Level C Weaker warm advection BC Level B 2. A Cold Advection Decreasing with Height Stabilization Warm Advection Increasing with Height Stabilization D o o Making the most of Doppler Isodops Stabilization requires the Isodop to veer with height/range. CAA angle increasing with range/height. WAA angle decreasing with range/height. Once again … for Stabilization Isodop veers with height/range Note: VWS Depth kept constant. Changing the Thermal Advection Intensity by changing the subtended angle (amount) of the directional wind shear. Increasing the angle, decreases the enclosed area.

Instability D Level D Stronger cold advection CD Level C Destabilization Weaker cold advection BC C Level B 1. A B Level D Weaker warm advection CD Destabilization B Level C Stronger warm advection BC Level B 2. A C Cold Advection Increasing with Height Destabilization Warm Advection Decreasing with Height Destabilization D o o Making the most of Doppler Isodops I have included this since most are interested in increasing instability. Destabilization requires the Isodop to back with height/range CAA angle decreasing with range/height. WAA angle increasing with range/height. Once again … for Destabilization Isodop backs with height/range Note: VWS Depth kept constant. Changing the Thermal Advection Intensity by changing the subtended angle (amount) of the directional wind shear. Increasing the angle, decreases the wind shear and the enclosed area.

Doppler Example Isodops for Increasing Instability – Differential Warm Advection in the Vertical
Southeast of the radar isodop CD subtends a veering, clockwise angle with range/height. This is warm advection. Warm advection CE is stronger than that for ED. The air mass is strongly destabilizing southeast of the radar. Isodop backs with height/range. For AB, AF and FB, the air mass northwest of the radar is also destabilizing Even more …larger angle AF in about the same height interval as CE. Stronger Destabilization Larger angle Along range ring B F A Smaller angle Along range ring The Virga Hole Weaker Destabilization Isodop Backs C Making the most of Doppler Isodops Note that the warm advection southeast of the radar from CD, is distinctly different that the warm advection described along the zero line from AB northwest of the radar. Also note that virga normally penetrates 3 to 4 km below a precipitation deck. Northwest of the radar the AB warm advection occurs through roughly the same vertical depth as to the southeast vector CD. Within the CB layer, the height change is more or less equally distributed between the vectors AF and FB. As explained previously, the amount of the angle subtended by each arc gives the wind shear and thus the VWS associated with AF must be greater (greater angle for the same height differential) than that associated with FB (smaller angle for the same height differential) . Layer AB is destabilizing through differential warm advection in the vertical. The CD warm advection occurs through roughly the same vertical depth as AB but most of the angle is subtended by the arc CE with a minimal angle subtended by ED. The height change of vector CE is much smaller than that of ED. The combination of strong direction shear over a small height interval means that the thermal advection associated with CE is much greater than that associated with ED. Thus layer CD is becoming much more unstable. When the thermal advection of AB is compared with that of CD: Both are veering Both are warm advection AB are CD are both destabilizing AF is longer than CE so the VWS is correspondingly larger. AB is destabilizing faster than CD E Isodop Backs with height (relative to the range rings) D Destabilization

Doppler Analysis & Diagnosis Strategies
An operational guide to getting the most information from Doppler radar: Look for Something “Odd” Determining the actual Wind Direction and Speed – Blue towards Red Away Curvature from direction & Mass confluence from speed Determining VWS - Wind backing & veering with height for Thermal Advections Angle subtended by Isodop veers for Warm Advection Angle subtended by Isodop backs for Cold Advection Determine Trends in the VWS - Angle between the Isodop and Range Rings If angle (area) increases (in time) then vertical wind shear/thermal advection is decreasing If angle (area) decreases (in time) then vertical wind shear/thermal advection is increasing Determining Stability Trends -Isodop backing & veering with height relative to range rings For Stabilization Isodop veers with height/range For Destabilization Isodop backs with height/range Stabilization/Destabilization rate stronger for longer legs… Diagnosing Vertical versus Spatial wind discrepancies Along a Range Ring versus along Radial … some of this is probably new to you … I made it up :>) Increasing Decreasing Stronger Destabilization An operational guide to getting the most information from Doppler radar: Look for Something “Odd” Determining the actual Wind Direction – Blue towards Red Away Determining Wind backing & veering with height Isodop veers for Warm Advection Isodop backs for Cold Advection Determine Trends in the Angle between the Isodop and Range Rings If angle increases (in time) then vertical wind shear/thermal advection is decreasing If angle decreases (in time) then vertical wind shear/thermal advection is increasing Determining Isodop backing & veering with height relative to range rings For Stabilization Isodop veers with height/range For Destabilization Isodop backs with height/range Stabilization/Destabilization rate stronger for longer legs… Diagnosing Vertical versus Spatial wind discrepancies Along a Range Ring versus along Radial … some of this is probably new to you … I made it up :>) Stronger Destabilization Discontinuities in the Vertical Follow the range rings Discontinuities in the Horizontal Tend to be lines Not along range rings

A isodop veering with height means…
Stabilizing Isodop veers Destabilizing Isodop backs A B C D A B C D 10 Warm advection with time Warm advection in space Stabilization if the veering increases with height Destabilization if the veering decreases with height All of the above None of the above = Backing

A isodop backing with height means…
Destabilizing Isodop backs A B C D A B C D Stabilizing Isodop veers 10 Cold advection with time Cold advection in space Stabilization if the backing decreases with height Destabilization if the backing increases with height All of the above None of the above

Thermal Advection type is determined by the angle from the radar subtended by the isodop ?
10 A B C D B A C Backing = Cold Advection Veering = Warm Advection D True False

Thermal Advection intensity is determined by the angle between the range rings and the isodop ?
10 Strong if angle small – isodop follows range rings Weak if angle large – isodop follows radials A B D A B D Strong Weak Strong Weak True False

Air mass stabilization is diagnosed by:
10 Backing of the isodop with height (relative to the isodop) Veering of the isodop with height (relative to the isodop) Backing of the isodop with height (relative to the radar site) Veering of the isodop with height (relative to the radar site)

Air mass destabilization is diagnosed by:
Backing of the isodop with height (relative to the isodop) Veering of the isodop with height (relative to the isodop) Backing of the isodop with height (relative to the radar site) Veering of the isodop with height (relative to the radar site)

A B D A B D A B D A B D A B C D

The Doppler Twist Signature - Example
White vectors match the colours from one level to a higher level – difficult to do. Direction of rotation indicates the type of thermal advection associated with the Doppler Twist. Length of the vectors indicate the relative magnitude of the thermal advection. An example of the Virga Hole Signature The Virga Hole The backing and veering of the zero line signature can be augmented by the Doppler Twist Signature. The Doppler Twist signature tends to be observed below the top of a layer. Different wind regimes from above the layer, mix/blend with the wind regime below the layer. Typically the top of a layer is a stable frontal zone with the mixing layer immediately beneath the frontal surface. As the name implies, the properties of the warm over-riding air aloft are blended with those of the cold air underneath in the mixing layer. Temperature, humidity and wind are the main air mass properties that are blended in this mixing layer. In the case of mixing the wind, the Doppler signature immediately under the frontal inversion resembles the pattern one would achieve if the Doppler colours are twisted like a lid until at the level (shortest radar range) where the winds are those of the unmixed colder air flow beneath. By matching colours from above and below the mixing layer, one can deduce the type and amount of wind shear between the to levels. Vertical discontinuity example. This veering lid twist signature would indicate a warm frontal surface. Veering Lid Twist Signature

White vectors match the colours from one level to a higher level – difficult to do. Direction of rotation indicates the type of thermal advection associated with the Doppler Twist. Length of the vectors indicate the relative magnitude of the thermal advection. An example of the Virga Hole Signature Lower Virga 210o 260o The Virga Hole 260o Virga Vertical discontinuity example. This veering lid twist signature would indicate a warm frontal surface. Higher

The obvious white line separates different wind regimes in the vertical. It also separates regimes of differing Doppler texture. Above the white line the Doppler texture is uniform and characteristic of snow. Below the white line the texture is lumpy like oatmeal and characteristic of rain. There is Virga – no rain to the ground. Consider the dashed line. The white line is the warm front. The layer immediately below is where the snow is melting into rain. See the Doppler Texture… I would have really liked the Dual Polarized imagery to go with this. I would also like a conventional radar PPI to show the bright band and to confirm this Doppler Texture analysis and diagnosis. Inherent in the Radar Palette and the Satellite Palette is the largely unspoken truism that the more evidence one can garner for a particular analysis or diagnosis, the more likely is that the analysis and diagnosis are correct. Is the dashed line a better analysis for the warm front! Were we analyzing the melting layer before … Typically cold air gets deeper & warm front gets higher to the north. Keep an open mind & get all the data you can!

12Z March 10, 2009 Virga R-R Winds veer from SE at the surface to SSW in 2.6 km Any chance of ZR-? Nil chance of ZR- due veering, warm advection under the warm front – no below freezing layer at ground. NO ZR- Note that the meteorologist on shift never even did the surface analysis. I wonder how the meteorologist would be able to complete an analysis and diagnosis? Doppler adds a lot of information to the surface map…

12Z March 10, 2009

Doppler and the Conveyor Belt Conceptual Model
North of the Surface Warm Front Conceptual Models The Conveyor Belt Conceptual Model is a very important operational tool as it includes all important weather events. R = Right of the Col C = Centered on the Col L = Left of the Col End

The Conveyor Belt Conceptual Model
Veering Div Backing NLY Flows Sinking Isentropically SLY Flows Rising Isentropically Wind direction and speed diagnosis should be completed independently in each conveyor belt Given the nature of isentropic flow, this is a prudent mode of diagnosis. Isentropic flows stay relatively separate and maintain their distinctive properties. The Doppler characteristics depicted in the CCB are separate from those in the WCB. When added, instructive patterns are revealed. Think in 3-D End

Vertical Deformation Zone Distribution & CBM Simplified Summary
WCB overrides the warm front CCB undercuts the warm front CCB CCB wind shear variable Nil VWS Veering Frontal surface overlies mixing layer C Backing Looking along the WCB flow: In WCB right of the Col expect veering winds with height – Katabatic (red for stop) warm front In WCB approach to the Col expect maximum diffluence – the eagle pattern with ascent and increasing pcpn In WCB to the left of the Col expect backing winds with height – Anabatic (green for Go) warm front WCB DCB Typical distributions of the conveyor belts and the associated deformation zones. Recall from the satellite palette that the deformation zone is actually a cross-section of the deformation sheath that encases an isentropic flow. Similarly, the vorticity centres depicted in the deformation zone conceptual model are actually vortex tubes that also slope in the vertical along with the deformation sheath. The Warm Conveyor Belt (WCB) typically rises isentropically with poleward (both northeasterly and northwesterly) motion and time. The WCB is shown with no vertical wind shift but typically it veers with height which is consistent with warm air advection. The Cold Conveyor Belt (CCB) typically sinks isentropically with equatorward (southwesterly) motion and time. The CCB typically backs with height which is consistent with cold air advection. The Dry Conveyor Belt (DCB) typically sinks isentropically with equatorward (southeasterly) motion and time. In the “dry slot” of the comma pattern, the DCB is typically rising isentropically with poleward (northeasterly) motion and time. The DCB typically veers with height with the approaching upper ridge. The flow ahead of the conveyor belt system has not been typically described but is the remains of the dry conveyor belt caught up in the upper ridge circulation. (Chadwick has described it in unpublished work.) This circulation is dry and subsiding with poleward (northwesterly) motion and time. The portion of the flow that turns southwesterly dry rises with equatorward (southwesterly) motion and time. This portion of the CCB typically veers with height which is consistent with warm air advection west of the upper ridge. The slope of the isentropic surfaces can be inferred from the overlap of the deformation zones. The slope of the isentropic surfaces can also be used to analyze instability. Isentropically speaking, sinking cold air and rising warm air converts thermal energy into kinetic energy. The vertical motions of dry air is not so simple isentropically speaking – have to ponder this! The introduction of isentropic thinking to NinJo will make the investigation of these concepts much easier. C C DCB End

CCB Doppler Diagnosis – Conceptual Models
The CCB Conceptual Model is independent of that in the WCB. Like Mr. Potato Head, one can mix and match conceptual models in the distinctly different conveyor belts. B B C C A A The Beaked Eagle The Headless Eagle A is the radar site AB is backing with height indicative of cold advection where really there should be veering as a result of the Ekman Spiral BC is veering with height indicative of warm advection B is the front with the mixing layer hidden in the cold advection This is a strong cold advection The warm front will be slow moving or stationary The best Beaked Eagle always has strong cold advection in the PBL. A is the radar site ABC is all veering with height indicative of warm advection. Layer AB is apt to be partially the result of the Ekman Spiral BC is veering with height indicative of warm advection Where is the front and the mixing layer? The cold advection is not apparent and the warm front will advance The Headless Eagle has nil cold advection in the PBL. One must always attempt to identify the location of the boundaries between the conveyor belts. The methods to do this are: Consider the ever present Ekman Spiral which should cause veering with height. There will be an abrupt change in the wind direction and speed (gradient wind) at the top of the PBL and the Ekman Spiral. Know the expected characteristics of the conveyor belt one is diagnosing by placing the Doppler data into the conveyor belt pattern and employing situational awareness. Keep the mixing layer of any front within the cold air mass. The frontal surface is always higher than this mixing layer. To my knowledge, I invented this. I haven’t seen anyone else present this material. -Be Alert for ZR -ZR not a serious threat End

WCB to the Right of the Col
The Warm Right Wing Stoop CM The eagles right wing is folded in as if it is about to swoop down. The left wing is still fully extended to catch the lift of the WCB. C o Signature of Warm Frontal surface Warm advection Within the CCB: Probable Ekman spiral nearest surface Probable cold advection above Ekman spiral Cold CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Mixing layer Warm frontal surface Left Wing Right Wing Warm CB Within the WCB: East of radar veering, warm advection West of radar nil VWS End

Common location for virga and the virga hole A
B Warm Frontal Cross-section along Leading Branch of the Warm Conveyor Belt (WCB) Common location for virga and the virga hole A WCB WCB oriented for maximum frontal lift Virga Precipitation Increasing CCB Moistening WCB oriented for less frontal lift Lower Hydrometeor Density Mixing Zone Surface Warm Front CCB A B Cold air in Cold Conveyor Belt (CCB) deep and dry Notes: All descriptive terms are intended to be comparative between the various conveyor belts in the Conveyor Belt Conceptual Model. All quantities are intended to be the average or typical values Virga may be the result of melting snow or evapourating rain to cause the reduced hydrometeor density and thus increased visibility or reduced obstruction to visibility These comments will need validation – many are just my simple operational observations The slope of the warm front should be more shallow because this portion of the WCB is not as strong suggesting that the isentropic lift is more gentle and more spread out over a broader distance. This is also consistent with the observed cloud types of cirrostratus. This portion of the cold front should be colder and drier as it is fresh out of the preceding ridge of high pressure. This helps evapouration of the precipitation. Only the highest portions of the WCB are likely to experience frontal lift and thus possible produce hydrometeors. This portion of the warm front is most likely to be inactive or katabaic so that precipitation processes are less likely and if they do occur, they are less likely to be intense enough to produce precipitation to the ground. Just poleward of the warm front, the cloud type is likely to be altostratus or cirrostratus. Precipitation extends typically extends thousand feet below precipitation Moist portion of Warm Conveyor Belt (WCB) is high and veered from frontal perpendicular – katabatic tendency Dry lower levels of WCB originate from ahead of the system and veered from frontal perpendicular WCB typically veers with height (it is after all, a warm front) Frontal slope is more shallow than the typical 1:200 Precipitation extends equidistant into the unmodified CCB Precipitation extends further into the moistened, modified CCB End

Inactive or Katabatic Warm Front
Descent into DIV Speed above front Frontal Speed Winds in warm air Above front slower Than front One only needs to apply the equation of continuity to explain the impact of a veering wind in the warm air above the warm frontal surface. If the wind veers above the frontal surface, then that wind is less than the forward speed of the warm front. The air is divergent at this height and air must be descending to fill the void through continuity. Such a warm front with veering winds above the frontal surface must be katabatic and relatively inactive. I have associated the red colour with the katabatic front because of the association of red with the stop sign. Winds veer with height above the warm front to the right of the COL Veering winds mean stable Knot active Red for “Stop” End

WCB Approaching the Col
The Warm Screaming Eagle CM Both wings are fully extended to catch the lift of the WCB. This is a divergent signature. C Warm CB Warm frontal surface o Mixing layer Signature of Warm Frontal surface discontinuity Within the CCB: Probable Ekman spiral nearest surface Probable cold advection above Ekman spiral Cold CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Left Wing Right Wing Within the WCB: East of radar veering, warm advection – katabatic warm front. West of radar backing, cold advection – anabatic warm front. End

Common location for both precipitation and virga
Warm Frontal Cross-section along Central Branch of the Warm Conveyor Belt (WCB) A Common location for both precipitation and virga WCB WCB oriented for maximum frontal lift Virga Precipitation Increasing CCB Moistening Lower Hydrometeor Density Mixing Zone Surface Warm Front Precipitation At Surface CCB A B Cold air in Cold Conveyor Belt (CCB) more shallow and moist Notes: All descriptive terms are intended to be comparative between the various conveyor belts in the Conveyor Belt Conceptual Model. All quantities are intended to be the average or typical values Virga may be the result of melting snow or evapourating rain to cause the reduced hydrometeor density and thus increased visibility or reduced obstruction to visibility These comments will need validation – many are just my simple operational observations. This will be made easier with isentropic thinking and NinJo. Compared to the previous slide and the leading branch of the WCB cross-section: The depth of the WCB with a component of flow normal to the warm front is deeper. The cold air mass is increasing moist from the precipitation. The area of precipitation at the ground will show rapid increase as a result of the precipitation extending further downward into the moistened, modified CCB. The expansion of the precipitation area is a result of the moistened CCB and not any increases in the precipitation processes. The warm front has equal probability of being anabatic or katabatic. Just poleward of the warm front, the cloud type is likely to be altostratus Moist portion of Warm Conveyor Belt (WCB) is thicker, higher and perpendicular to front Lower levels of WCB have the same origin as the upper level of the WCB - frontal perpendicular WCB shows little directional shift with height. A greater WCB depth is frontal perpendicular Frontal slope is near the typical 1:200 Precipitation extends further into the moistened, modified CCB. Horizontal rain area begins to expand as CCB moistens. End

A Beaked Warm Screaming Eagle has CAA in the PBL
Need to emphasize The PPI nature of the Doppler scan - The cone D A G C B E F This is the idea. I am contemplating: Leaving this material as is and letting COMET build it in Flash from the letters and the descriptive text Building this in HTML as the roll-overs area easier in HTML Note that this may also be done using links to text files. I will format the text box to be as small as possible and located where it does not obscure the image. This approach works fairly well. Note that the animations in PPT obscure the lettering unless the presentation is in “play” mode. It makes it more difficult to work on. The animations highlight the best way to deduce winds vectors from the Doppler signal. The work below should highlight how the winds in the CCB are diagnosed separately from the winds in the WCB. The resultant diagnoses are then added together to create the mythical creature desired. A is at the radar site. The arc A to B represents the veering wind associated with the warm front as seen to the east of the radar. Is this the mixing zone or the warm air advection in the CCB? The warm frontal surface must be at the top of the mixing zone. The arc A to C is the same representation to the west. The difference in the height of B and C represents the slope of the warm front. The shape of the outbound reds in the arc A to B defines the eagles head. The stronger the low level CCB the “brighter” will be the “beak”. The more curved the A to B veering wind is the more prominent will be the beak. The best “beak” will be displayed by a backing wind in the lower part of the A to B layer. This backing wind is indicative of cold air advection within the CCB. This is suggestive that the cold layer underneath the warm frontal surface coninutes to cool with fresh reinforcements. The cold air is likely to become deeper and more entrenched thus preventing the northward progression of the warm front which is really the southward advance of the cold air. The smallest “beak” will be displayed by a veering wind in the lower part of the A to B layer. This veering wind is indicative of warm air advection within the CCB. This is suggestive that the cold layer underneath the warm frontal surface is warming and is likely to dissipate allowing the northward progression of the warm front which is really the northward retreat of the cold air. B and E are very close to being on the same radial which means that there is no change in wind direction and no thermal advection. From C to D there is a slight backing of the wind which becomes more pronounced at point F. This backing of the winds increases the height of the right wing. If we look at the radial from A to F and the winds are at right angles, then at point F our winds are from 160 degrees. Contrast this with what happens west of the radar. Between points E and G the winds back slightly and are about 180 degrees at point G. This backing of the winds increases the height of the right wing. Between points G and H the winds veer. At point H if we look at the A to H radial and go 90 degrees we define a wind direction of about 215 degrees. The 20 to 40 degree wind direction difference between D to F and G to H is what gives our eagle it’s wing shape. The 215 winds to the east of the radar and the 160 winds to the west indicate we are close to the col of the conveyor belt. As we move further west or as the warm conveyor belt moves over this radar the left wing of the eagle should maintain itself or become more curved and the right wing should straighten out. I think a simple streamline example will illustrate this. H A Beaked Warm Screaming Eagle has CAA in the PBL The Warm Screaming Eagle Conceptual Model End

WCB to the Left of the Col
The Warm Left Wing Stoop CM The eagles left wing is folded in as if it is about to swoop down. The right wing is still fully extended to catch the lift of the WCB. C o Signature of Warm Frontal surface … odd? Signature of Warm Frontal surface Warm advection Within the CCB: Probable Ekman spiral nearest surface Probable cold advection above Ekman spiral Cold CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Mixing layer Right Wing Warm frontal surface Left Wing Warm CB Within the WCB: West of radar backing, cold advection East of radar nil VWS End

Common location for precipitation to ground!
B Warm Frontal Cross-section along Trailing Branch of the Warm Conveyor Belt (WCB) A Common location for precipitation to ground! WCB WCB oriented for maximum frontal lift Virga Precipitation Increasing CCB Moistening Lower Hydrometeor Density Mixing Zone Surface Warm Front Precipitation At Surface CCB A B Cold air in Cold Conveyor Belt (CCB) even more shallow and more moist Notes: All descriptive terms are intended to be comparative between the various conveyor belts in the Conveyor Belt Conceptual Model. All quantities are intended to be the average or typical values Virga may be the result of melting snow or evapourating rain to cause the reduced hydrometeor density and thus increased visibility or reduced obstruction to visibility These comments will need validation – many are just my simple operational observations Compared to the previous slide and the central branch of the WCB cross-section: The depth of the WCB with a component of flow normal to the warm front is even deeper. The cold air mass is increasing moist from the precipitation. The area of precipitation at the ground will continue to show rapid increase as a result of the precipitation extending further downward into the moistened, modified CCB. The expansion of the precipitation area is a result of the moistened CCB and not any increases in the precipitation processes. The warm front is more likely to be anabatic or active. Just poleward of the warm front, the cloud type will certainly be nimbostratus Moist portion of WCB is thicker, higher and backed from frontal perpendicular – anabatic tendency Lower levels of WCB have the same origin as the upper level of the WCB WCB backs slightly with height in spite of the warm air advection. A greater WCB depth is frontal perpendicular Frontal slope likely steeper than the typical 1:200 Precipitation extends further into the moistened, modified CCB. Horizontal rain area expands rapidly as CCB moistened. End

B A G D A C B F End The Left Wing Stoop CM
On the west side of the warm conveyor belt the eagle has indeed lost it’s right wing. The left wing continues to show the 40 degrees of backing of the winds into the southeast. But now the right wing is also backing but by only about 10 or 15 degrees. The flow is still diffluent but not as much as in the middle of the arm conveyor belt. End

Active or Anabatic Warm Front
confluence UP Speed above front Frontal Speed Winds in warm air Above front faster Than front One only needs to apply the equation of continuity to explain the impact of a backing wind in the warm air above the warm frontal surface. If the wind backs above the frontal surface, then that wind is faster than the forward speed of the warm front. The air is convergent at this height and air must be ascending cue to continuity. Such a warm front with backing winds above the frontal surface must be anabatic and relatively active. I have associated the green colour with the anabatic front because of the association of green with “go”. Winds back with height above the warm front to the left of the COL Backing winds mean unstable Active Green for “Go” End

Veering winds above a frontal surface denotes the front as:
10 Cold Front – Katabatic – Veering One only needs to apply the equation of continuity to explain the impact of a veering wind in the warm air above the cold frontal surface. If the wind veers above the cold frontal surface, then that wind is stronger than the forward speed of the cold front. The air is divergent at this height and air must be descending to fill the void through continuity. Such a cold front with veering winds above the frontal surface must be katabatic. Cold Front – Anabatic – Backing One only needs to apply the equation of continuity to explain the impact of a backing wind in the warm air above the cold frontal surface. If the wind backs above the cold frontal surface, then that wind is less than than the forward speed of the cold front. The air is convergent at this height and air must be ascending through continuity. Such a cold front with backing winds above the frontal surface must be anabatic. Warm Front – Katabatic – Veering One only needs to apply the equation of continuity to explain the impact of a veering wind in the warm air above the warm frontal surface. If the wind veers above the frontal surface, then that wind is less than the forward speed of the warm front. The air is divergent at this height and air must be descending to fill the void through continuity. Such a warm front with veering winds above the frontal surface must be katabatic. Anabatic Katabatic Warm Frontal Cold Frontal Advancing Stationary

Backing winds above a frontal surface denotes the front as:
10 Anabatic Katabatic Warm Frontal Cold Frontal Advancing Stationary

Warm Frontal Hodographs

Downstream from the Col Under the Col Upstream from the Col
Given the Doppler Radar image, where is the radar relative to the conveyor belt conceptual model? 10 The backing and veering of the zero line signature can be augmented by the Doppler Twist Signature. The Doppler Twist signature tends to be observed below the top of a layer. Different wind regimes from above the layer, mix/blend with the wind regime below the layer. Typically the top of a layer is a stable frontal zone with the mixing layer immediately beneath the frontal surface. As the name implies, the properties of the warm over-riding air aloft are blended with those of the cold air underneath in the mixing layer. Temperature, humidity and wind are the main air mass properties that are blended in this mixing layer. In the case of mixing the wind, the Doppler signature immediately under the frontal inversion resembles the pattern one would achieve if the Doppler colours are twisted like a lid until at the level (shortest radar range) where the winds are those of the unmixed colder air flow beneath. By matching colours from above and below the mixing layer, one can deduce the type and amount of wind shear between the to levels. Vertical discontinuity example. This veering lid twist signature would indicate a warm frontal surface. Downstream from the Col Under the Col Upstream from the Col In the warm sector

Downstream from the Col Under the Col Upstream from the Col
Given the Doppler Radar image, where is the radar relative to the conveyor belt conceptual model? 10 The Left Wing Stoop CM On the west side of the warm conveyor belt the eagle has indeed lost it’s right wing. The left wing continues to show the 40 degrees of backing of the winds into the southeast. But now the right wing is also backing but by only about 10 or 15 degrees. The flow is still diffluent but not as much as in the middle of the arm conveyor belt. Downstream from the Col Under the Col Upstream from the Col In the warm sector

The Doppler Radar of the cold conveyor preceding a warm front shows the “Beaked Eagle”. What can be said about this front? A B C The Beaked Eagle Radar Strong cold advection from A to B B is the lower level of the frontal mixing zone BC is the warm frontal mixing zone Cold advection overpowers the typical frictional Ekman Spiral Warm front nearly stationary Beware of freezing precipitation All of the above None of the above. A is the radar site AB is backing with height indicative of cold advection where really there should be veering as a result of the Ekman Spiral BC is veering with height indicative of warm advection B is the front with the mixing layer hidden in the cold advection This is a strong cold advection The warm front will be slow moving or stationary

Doppler Patterns - Outline
Doppler Basics Doppler Signatures Basic Signatures Wind Analysis (Convection, Synoptic Flows) Advanced Signatures Atmospheric Diagnosis (VWS, Stability) Conveyor Belt Conceptual Model (CBCM) Summary Keep Looking UP! There is much more that can be demonstrated using Doppler Radar in an operational setting but this is a start. Remote sensing is your friend since you do not want to experience severe weather first hand. You may want to see a tornado before you die … but not just before you die! Phil the Forecaster Chadwick Thank you for your attention! Remote sensing is your Friend! Take Home Message (THM): Doppler Radar is useful to A&D winds, VWS, Stability & Stability Trends!

And Now You Know What This Means…
The Headless Screaming Eagle Conceptual Model No Cold Advection in PBL Where is the Conveyor Belt? Where is Frontal Surface? ZR-? Headless means that there is veering through the PBL. One needs cold advection and backing to create a beak and head of an eagle. Thus a eagle with a head is an important pattern for freezing precipitation should the temperatures be correct for such precipitation. What is the orientation of the front? Should the front be perpendicular to the point where the radar intersects the frontal surface to the north and to where it intersects the frontal surface to the south. These points will give the maximum slope of the frontal surface and shouldn’t the front be perpendicular to this line… These patterns happen every day – somewhere…

Britt Radar Further to the North

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