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Weather Charts.

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Presentation on theme: "Weather Charts."— Presentation transcript:

1 Weather Charts

2 Current Weather Products
Observations Surface Analysis Charts Constant Pressure Charts Weather Depiction Charts Lifted Index Charts Radar Summary Charts Forecast Charts Short Range Surface Prognostic Chart Low level Significant Weather Prognostic Chart

3 Surface Analysis Chart
Shows the “big picture” – helps plan flights around WX Depicts Sea level pressure Position of highs, lows, ridges and troughs Position of fronts Position of boundaries Overview of winds, temperatures and dew points Issued every 3 hours Valid for 6 hours Available at:

4 Surface Analysis Chart
Low Sea Level Pressure –4mb interval lines - Line below # is pressure trend Warm front stationary front Cold front – Pips show direction of movement High - Number adjacent is central pressure Sea Level pressure (first 10 or 9 digits omitted) or ceiling height Tropical wave Data Wind Temp Sky cover – If station symbol is square then automated data was used Dew Point

5 Surface Analysis Chart

6 Surface Analysis Chart

7 Surface Analysis Chart

8 DUATS Surface Analysis Chart

9 Constant Pressure Charts
Similar to the surface analysis chart but at different pressure levels (altitudes will vary) 850 MB chart ≈ 5,000’ 700 MB chart ≈ 10,000’ 500 MB chart ≈ 18,000’ Provides a 3D view of large areas – interpolate between charts Data gathered through balloons Shows winds and temps – can identify jet stream / freezing risks for example Charts available at:

10 Constant Pressure Charts
X Marks high/low center Issue date/time Wind Level Contour line area of = height in meters (850 MB omits 1 before and 700 omits 2 or 3 before – which ever makes the number closer to 3,000 meters) e.g. 309 = 3309 meters or 10,754’ – Look at gradients - wind speed proportional to gradients (close = high winds). Contours can be interpreted in the same manner as isobars on the surface chart (e.g. high altitude=high pressure area) Some charts also show: isotherms – areas of equal temperature – bold dashed line isotachs – constant wind speed areas – short fine dashed line with __K

11 Historic (FAA) Constant Pressure Chart
Wind Latitude Temp Height / pressure altitude Temp – DP spread Height change / aircraft type Satellite data Balloon / Ground station Data Temp / Isotherm Airplane observation Longitude

12 Duats Constant Pressure Chart

13 Weather Depiction Chart
Broad overview of flying conditions – IFR (<3sm vis;1,000’), MVFR (3 to 5sm vis;1k to 3k ceiling), VFR (>5sm vis; >3,000 ceiling) Also shows fronts and troughs (except 10 and 23Z) Prepared 8 X per day

14 Weather Depiction Chart
IFR MVFR Precipitation / Vis obstructions Sky cover AGL cloud height Legend Data

15 Weather depiction Chart Symbols
NB: Symbols are the same as the Surface Analysis Chart

16 DUATS Weather Depiction Chart

17 Radar Summary Chart Aids in preflight planning by identifying general areas and movement of precipitation and/or thunderstorms Issued hourly Shows: Radar echos Types of precipitation Movement of cells Tops of precipitation Severe Thunderstorm and Tornado Watch areas DOES NOT SHOW clouds or fog

18 Radar Summary Chart

19 Radar Summary Chart Individual cell movement is indicated by an arrow with the speed in knots entered as a number at the top of the arrow head. Highest echo height in the area is shown above a short line, with the top height displayed. Severe weather watch areas are outlined by heavy dashed lines, usually in the form of a large rectangular box.

20 NWS Radar Summary Chart

21 Nexrad Radar

22 Lifted Index Chart Provides plot of the lifted index and K index values Lifted Index is a measure of atmospheric stability – it is a comparison of predicted temperature change from the surface (2° saturated or 3° unsaturated) less actual temperature change from the surface to 500mb (18,000 msl +/-) Positive LI – colder so stable air Negative LI – warmer so less stable Zero LI – neutral stability Becomes more stable with decreased dew point, decreasing surface temperature or increasing 500 mb temperature Severe thunderstorm guide 0 to -2 weak potential; -3 to -5 moderate potential; ≤-6 Strong potentia;

23 Lifted Index Chart K Index – used mostly by meteorologists
During warm season a large Ki indicates conditions favorable for thunderstorms In winter temperature terms completely dominate K index Ki < 20 – No chance of thunderstorms Ki 20 to 25 – Isolated thunderstorms Ki 26 – 30 – Widely scattered thunderstorms Ki 31 – 35 – Scattered Thunderstorms Ki > 35 – Numerous thunderstorms

24 Lifted Index Chart Lifted Index (LI) Severe Potential K-Index *
Airmass Thunderstorm Probability 0 to -2 Weak <15 near 0% 15-20 20% -3 to -5 Moderate 21-25 21-40% 26-30 41-60% < -6 Strong 31-35 61-80% 36-40 81-90% >40 near 100% It is essential to note that an unstable Lifted Index does NOT automatically mean thunderstorms. Look at the synoptic situation and if thunderstorms are expected to develop in the unstable air, this table may be used. * Use caution when applying these values in the western mountainous terrain due to elevation

25 Lifted Index Chart

26 Short Range Surface Prognostic Chart
Surface forecast of pressure systems, fronts and precipitation for two day period – 12, 24, 36 and 48 hours Uses Surface Analysis chart symbols Produced 4 x day for 12 and 24 hour periods; twice per day for 36 and 48 hour periods

27 Short Range Surface Prognostic Chart
Shading = >50% coverage; Unshaded precip indicates 30 to 50% coverage A bold, dashed, grey line is used to separate precipitation within an outlined area with contrasting characteristics Precipitation Trough

28 Short Range Surface Prognostic Chart

29 DUATS Low Level Weather Prognostic Chart

30 Low Level Significant Weather Prognostic Chart
Forecast of aviation weather hazards Preflight use 3 versions (High level (FL250-FL630); mid level (FL100-FL450) and low level (SFC-FL240)) 12 and 24 hour panels; additional charts for 30, 36 and 48 hours Depicts VFR, MVFR and IFR areas (top panel) Freezing levels (top panel) Turbulence (top panel) Fronts and pressure systems (lower panel) Available at:

31 Low Level Significant Weather Prognostic Chart

32 Low Level Significant Weather Prognostic Chart

33 Low Level Significant Weather Prognostic Chart

34 DUATS Severe Weather Outlook

35 DUATS Winds Aloft Forecast Chart

36 NWC AirMet / Sigmet Charts
Airmet Zulu - Icing Airmet Sierra - IFR Airmet Tango - Turbulence Freezing levels

37 Freezing Level Chart

38 Icing SLD (super-cooled large drop - includes freezing drizzle and freezing rain).

39 Turbulence

40 Infrared Satellite Chart

41 Visible Satellite Chart
Day Night


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