Presentation is loading. Please wait.

Presentation is loading. Please wait.

Meteorological Concepts for Soaring in the Western U.S. Dan Gudgel Meteorologist/Towpilot/CFIG.

Similar presentations

Presentation on theme: "Meteorological Concepts for Soaring in the Western U.S. Dan Gudgel Meteorologist/Towpilot/CFIG."— Presentation transcript:

1 Meteorological Concepts for Soaring in the Western U.S. Dan Gudgel Meteorologist/Towpilot/CFIG

2 Presentation Points 1. Weather Information Sources 2. Meteorology Points 3. Synoptic Scale Weather Patterns 4. A Forecast Funnel 5. Miscellaneous Info

3 1. Weather Information Sources Weather Data Internet (use search engines) Site addresses change frequently for this medium Customize access list for efficient data retrieval Review AC-006, Aviation Weather Review AC-45E, Aviation Weather Services Other Information Sources

4 Internet Weather Data Upper Air Temperature Soundings Observed and Forecast Weather Charts Model Forecasts Satellite Imagery Education / Explanations Soaring Category Info

5 National Weather Service NWS National Homepage Select area of interest (clickable map) All Western Region NWS Offices listed Numerous weather links Current weather Forecast models Satellite images Aviation Wx Center Other sites

6 Forecast Systems Laboratory Forecast Upper Air Temperature Soundings 40Km grid resolution Out to 16 Hours Spot forecasts (By airport)

7 Unisys Weather Upper Air Temperature Soundings Constant Pressure Charts Model Forecast Charts Education / Explanations

8 National Center for Atmospheric Research (NCAR) [et al.] Upper Air Data (Temperature/Relative Humidity/Wind Info) Other weather data

9 Other Weather Info Sources For the Aircraft Category Fixed base operators Soaring Society of America Associated sites Other Sources Newspapers NWS Weather Radio FAA DUATS

10 2. Meteorology Points Atmospheric Soundings Great Basin Applications Convection concepts Climate Aspects Local Influences

11 Sounding Basics Small day-to-day changes can make big differences in a soaring day's characteristics Spot observation versus need to assess task area air mass, including discontinuity lines Altitude noted by Pressure -850 mb Feet (MSL) -700 mb. 10,000 Feet -500 mb. 18,000 Feet

12 Sounding Sources University of Utah Upper Air Link Unisys Weather Upper Air Link

13 Lapse Rate Definitions

14 14 Lapse Rates Dry and Moist Adiabatic

15 Definitions - Stable/Unstable Dry Atmospheric Conditions Altitude Temperature + + ( d A B A - Temperature decreasing greater than Dry Adiabatic Lapse Rate denotes unstable atmospheric conditions B - Temperature not decreasing as fast as Dry Adiabatic Lapse Rate denotes more stable atmospheric conditions

16 16 Temperature Inversions Surface-Based and Aloft

17 Wind Shear Wind velocity is a change in speed and/or direction Temperature inversions are boundaries of air layers Shear zone may not be deep or turbulent but... Each layer of air can have a different characteristics: - Wind velocity - Moisture - Parameter gradients Altitude Temperature + + Wind SHEAR ZONE

18 18 Profiles A mixed atmosphere is near-adiabatic (left) Subsidence from high pressure caps convection but high enough to facilitate soaring over terrain (right) Temperature Alt. d d

19 19 Surface-Based Inversion Established with Time d Alt. Temperature (0600 LT)(0100 LT)(2000 LT)(1700 LT) Time of Day

20 20 Surface-Based Inversion Erosion with Time d Alt. Temperature (0600 LT)(0900 LT)(1100 LT)(1400 LT) Time of Day

21 Cloud Base / Moisture Layers T / DP Closure ­Possible Cloud Layers Moist Adiabatic Lapse Rate

22 The Drying Process Rising,Cooling Condensing Sinking, Heating Drying Owens Valley Sierra Nevada Great Basin San Joaquin Valley 5K Ft Moisture, Deficit Air MSL White Mtns 5000 Ft MSL Ft MSL

23 De-Stabilizing Process Colder Air Advection above, and/or Warm Air Advection below will de-stabilize Delta-T increase! Moisture presence also de-stabilizes

24 Basin Thunderstorm / Microbursts Develop Adjacent cells Classic short duration 60Kt+ Sink Rates Regardless of cell size Wind shifts Degrade ceiling and visibility

25 25 Mojave Desert Downburst Courtesy of Caracole Soaring, California City, CA)

26 Microburst Sounding

27 Thunderstorm Activity (#1) Presence of "cap"; and "penetration" of cap (observed time vs. forecast time?) Winds aloft Cell movement Anvil spread

28 Thunderstorm Activity (#2) Air mass Thunderstorms Favored spots Outflow

29 Radar

30 30 Classic Supercell Thunderstorm Nautical miles Light Rain Moderate/Heavy Rain & Hail Supercell Thunderstorm (top view) Anvil Edge Gust Front WSR-88D Radar Image N Hook echo National Weather Service

31 Convection Circulation Temperature Differences Uneven heating leads to differing air density and ultimately supports a thermal circulation Terrain/slope contributions Surface heating capacity = f(ground and lower air mass moisture content)

32 Elevated Thermal Source Great Basin Mountains Mountain slopes normal to incoming energy Less attenuation Air density Moisture Pollutants Less mass of air to heat for greater buoyancy

33 Climate and Other Influences Climate and Terrain Considerations Modifying Influences and Contributions Thunderstorm Indices

34 Climate and Terrain Great Basin Time of year Diurnal temperature spread Humidity factors Terrain rising aspects (and TAS)

35 Sunset / Sunrise / Normal Temps Reno, NV Sunrise / Sunset June 1 5:34 AM PDT / 8:20 PM PDT July 1 5:35 AM PDT / 8:30 PM PDT Aug 1 5:58 AM PDT / 8:12 PM PDT Sep 1 6:27 AM PDT / 7:30 PM PDT Normal Maximum/Minimum Temperatures June 81.5 / 44.3 ()T=37.2F) July 91.0 / 49.3 ()T=41.7F) Aug 89.7 / 47.2 ()T=42.5F)

36 Great Basin Temps

37 37

38 The Drying Process Rising,Cooling Condensing Sinking, Heating Drying Owens Valley Sierra Nevada Great Basin San Joaquin Valley 5K Ft Moisture, Deficit Air MSL White Mtns 5000 Ft MSL Ft MSL

39 Major Modifying Influences (#1) Washoe Zephyr Nevada Sinks Mono Lake Shear Basin Air Terrain "Holes"

40 Major Modifying Influences (#2) Topaz Flow Mammoth Lakes June Lake

41 Pressure Patterns Favorable for Great Basin Soaring High location (aloft) -Ridge aloft east of task area (or far west) Low pressure (aloft) -Not strong or close enough to bring strong gradient wind De-stabilizing Influences -Split flow in the upper wind field with weak trough Allows for Instability aloft but good surface heating Thermal Trough (surface) -Through interior CA (better if along the coast!)

42 Pressure Gradients (#1) Stable Air Movement to the Western Great Basin Great Basin to Interior California * 4 mb Reno to Sacramento delta-P inhibits Washoe Zephyr development

43 Pressure Gradients (#2) Stable Air Movement to the Western Great Basin South CA Coast to Desert Interior * Depth of marine layer greater than 1500' MSL * 3+ mb Los Angeles (LAX) to Daggett (DAG) Central CA Coast to Desert Interior * 6+ mb San Francisco to Las Vegas * Depth of marine layer greater than 2000' MSL

44 Thermal Detractors Macro-scale Level

45 Thermal Enhancers Great Basin

46 46 Mojave Desert Shearlines

47 47 Mono Lake Shear Line Typically present Example: 6/13/99

48 48 Mono Lake Shear Line

49 49 Mono Lake Shear Line

50 50 Flying M Shear Line Typically present Example: 6/14/99

51 51 Flying M Shear Line

52 52 Flying M Shear Line

53 53 Mountain Wave

54 54 Mountain Wave

55 55 Mountain Wave Wave Presence for Long Distance Flight Example: 6/15/99

56 Moisture Surges Warm Season Sources Southwest U.S. Monsoon -Low level and/or mid-level Significantly deep trough developing moisture field due to the dynamics -But a southwest flow is generally a very dry flow East Pacific hurricane activity -Mid/High Clouds with a major hurricane release of its accompanying moisture

57 57 East vs. West Great Basin Time of Year Sub-Tropical Moisture Progression –Parawon UT (Late June/Early July) –East NV (Mid-Late July) –West NV (Late July/Early August) Slower Thermal Processes –Dry west; Slower start per moisture-deficit –More attenuation; CA and local Haze –West NV, slightly lower terrain West Great Basin Enhancements –Shear line influences prevalent within 50 s.m. of the Sierra Nevada Front

58 58 Soaring = f(Moisture Changes) Moisture Contribution –Dew Points rise to the southeast over the Great Basin La Nina/El Nino Influences –La Nina Dry south; Thunderstorms develop less frequently –El Nino Moist ground delays (thermal) soaring season Upon initiation, more thunderstorm activity –Other Climatic Oscillations Impact? Arctic Oscillation, Pacific Decadal, Madden-Julian Oscillation Hypothesis: Annual Climate Changes Impact Soaring

59 Infrared Satellite Imagery Cloud top temperature Good delineator for high clouds

60 Water Vapor Satellite Imagery Moist and dry air boundaries Active convection often along interface Determine Raob representativeness of task area?

61 3. Synoptic-Scale Weather Patterns Weather Types Favorable to Long Distance Soaring Type #1: Four-Corner High Type #2: Strong Ridge Type #3: Low Center, Trough, Short-wave Proximity Type #4: Building Ridge Aloft

62 Type #1: The Four-Corner High High pressure centered aloft near the Four Corner area of the Southwest U.S. Most recognized, "Classic" long flight pattern Good low level heating de-stabilizes the air mass -Light surface wind -Lower layer warm air advection Monsoon moisture tap... therefore usually not a long-lived pattern Good soaring... but days get truncated with afternoon TSTMs... often widespread

63 Type #1: 6/18/88 ASI to Keeler and return

64 6/18/88 Raobs WMC 94/50 RNO 90/58 TPH 83/52 LAS 98/78

65 Type #2: Strong Ridge Light wind Low level heating Thermal trough well to the west of task area Impulse aloft over ridge axis; or, Ridge axis aloft east of the task area

66 Type #2: 8/9/96 Long-lived, extraordinary pattern Numerous 1000Km flights Over a 4-day period

67 8/9/96 WMC 98/48 RNO 95/53 TPH 95/61 LAS 99/80

68 Type #3: Low Center, Trough, or Short Wave Proximity Ridge axis to the east; Trough axis proximity De-stabilizing by cold air advection aloft But light wind and/or split in the jet aloft Thermal trough closer to NV; but... Low level Zephyr washout delayed Still able to heat lower levels Prevalent pattern for long distance soaring!

69 Type #3: 7/7/88 Flight of 350 miles

70 7/7/88 Raobs

71 Type #3(a): Proximity of Low Pressure Center

72 Type #3(a): 6/19/ Km flights from Truckee And Minden area

73 6/19/93 Raobs

74 Type #4: Building Ridge Aloft 2 Examples / Next 4 Slides

75 Type #4: 6/13/ Mile Flight

76 6/13/88 Raobs

77 77 Map Types also varied as season passed!

78 4. Weather Forecasting Forecast Funnel Soaring Indices Automated Soaring Forecasts Dr. Jack and BLIPMAP Other Automated Forecasts NWS IFPS (Gridded Data)

79 A Glider Pilots Forecast Funnel A Process of Soaring Forecast Refinement Site Climate Outlook Forecasts Extended and Zone Forecasts (2-7 Day) Persistence Flight Day

80 Soaring Indices (#1) Great Basin Thermal Index - Lift = f()T)

81 Soaring Indices (#2) Great Basin Soaring Index - Lift = f(Convection Altitude and )T)

82 Soaring Indices (#3) Great Basin Vertical Totals [)T(deg C) 850 mb to 500 mb ] - Upper 20s average to good - 30 to 34 very good excellent (too unstable many times)

83 Instability Indices (#1) Great Basin K-Index Uses Vertical Totals and 2 fixed reference levels )T(C) dew point(C) dew point depression(C) 5+ = some cumulus possibilities Thunderstorms increase in the range

84 Instability Indices (#2) Great Basin Lifted Index (LI) and Showalter Index (SI) Lower layer moisture influences on the convection process / thunderstorm indicator > 10 stable (weak convection) < -4 too unstable (severe weather)

85 85 Thermal Lift Indices Work Thermal Index (Williams/Higgins) Maximum Lift (Lindsay/Lacy) Soaring Support (Aldrich/Marsh) Soaring Index (Armstrong-Hill)

86 86 Wave Strength Forecasting Wave Nomogram (Herold/Armstrong)

87 87 Traditional Soaring Forecasts Persistence Nowcasting –Soundings –Satellite –Analysis Algorithm Use

88 88 Thermal Index Prediction (TIP) Dr. John W. (Jack) Glendening Estimate for the Current Day Thermal Soaring Potential Two Day Thermal Soaring Outlook Several Sites Mountain Top Experiment (Walker Ridge) URL: URL:

89 89 Boundary Layer Information Predictor Maps(BLIPMAP) Single Time or Sequence URL: Thermal Soaring Parameters (over a geographic region) -Numerical Model Outputs General Air Mass Lift

90 90 Wind Information Predictions (WINDIP) (Simple Mountain Wave Prediction) Alert WINDIP List Assumptions Longer Forecast Time Predictions URL:

91 91 Linear Wave Interpretation Page (LWIP) Description Interpretation Notes Links URL:

92 92 Automated Thermal Soaring Forecasts Two Parts: 1.Pure Model Output (top portion) 2.NWS Forecast Temps as base (lower portion) Limitations NWS Websites Walt Rogers (WX), MIC CWSU ZLA URL: where ***** is NWS Office Name, I.e., Hanford, Oxnard, etc.

93 93 Interactive Forecast Preparation System (IFPS) Man-Machine Mix Flagship Products Not Text -Forecasters Edit Gridded Data Graphical Products -Customer Requested Output

94 94 Gridded Data Graphical Display of Requested Weather Parameter(s)

95 5. Miscellaneous Information Aero-medical Considerations

96 Aeromedical Considerations Soaring good enough that...

97 Meteorological Concepts for Soaring in the Western U.S. Dan Gudgel Meteorologist/Towpilot/CFIG 134 South Olive Street Lemoore, CA (w) ext.223 (h)

Download ppt "Meteorological Concepts for Soaring in the Western U.S. Dan Gudgel Meteorologist/Towpilot/CFIG."

Similar presentations

Ads by Google