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Meteorological Concepts for Soaring in the Western U.S. Dan Gudgel Meteorologist/Towpilot/CFIG Presentation Points Weather Information Sources Meteorology Points Synoptic Scale Weather Patterns A Forecast Funnel Miscellaneous Info 1. Weather Information Sources Weather Data

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Meteorological concepts for soaring in the western u s l.jpg
Meteorological Concepts for Soaring in the Western U.S.

Dan Gudgel

Meteorologist/Towpilot/CFIG


Presentation points l.jpg
Presentation Points

  • Weather Information Sources

  • Meteorology Points

  • Synoptic Scale Weather Patterns

  • A Forecast Funnel

  • Miscellaneous Info


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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


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Internet Weather Data

  • Upper Air Temperature Soundings

  • Observed and Forecast Weather Charts

  • Model Forecasts

  • Satellite Imagery

  • Education / Explanations

  • Soaring Category Info


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National Weather Service

<http://www.weather.gov>

  • 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


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Forecast Systems Laboratory

<http://www-frd.fsl.noaa.gov/mab/soundings>

  • Forecast Upper Air Temperature Soundings

  • 40Km grid resolution

  • Out to 16 Hours

  • Spot forecasts

  • (By airport)


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Unisys Weather

<http://weather.unisys.com/index.html>

  • Upper Air Temperature Soundings

  • Constant Pressure Charts

  • Model Forecast Charts

  • Education / Explanations


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National Center for Atmospheric Research (NCAR) [et al.]

<http://www.rap.ucar.edu/weather/>

  • Upper Air Data

  • (Temperature/Relative Humidity/Wind Info)

  • Other weather data


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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


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2. Meteorology Points

  • Atmospheric Soundings

  • Great Basin Applications

    • Convection concepts

  • Climate Aspects

  • Local Influences


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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 . 5000 Feet (MSL)

    • 700 mb . 10,000 Feet

    • 500 mb . 18,000 Feet


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Sounding Sources

  • University of Utah Upper Air Link

    http://www.met.utah.edu/jhorel/html/wx/skewt.html

  • Unisys Weather Upper Air Link

    http://weather.unisys.com/upper_air/skew/index.html



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Lapse Rates

Dry

and

Moist

Adiabatic

14


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Definitions - Stable/Unstable

Dry Atmospheric Conditions

A - Temperature decreasing greater than Dry Adiabatic

Lapse Rate denotes unstable atmospheric conditions

+

A

B

Altitude

B - Temperature not decreasing as fast as Dry Adiabatic Lapse Rate denotes more stable atmospheric conditions

(

d

+

Temperature


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Temperature Inversions

  • Surface-Based and Aloft

16


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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 aircan have a different

    characteristics:

    - Wind velocity

    - Moisture

    - Parameter gradients

+

Wind

SHEAR

Altitude

ZONE

Wind

+

Temperature


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Profiles

  • A mixed atmosphere is near-adiabatic (left)

  • Subsidence from high pressure “caps” convection but high enough to facilitate soaring over terrain (right)

Alt.

Alt.

d

d

18

Temperature

Temperature


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Surface-Based Inversion Established with Time

d

Alt.

(0600 LT)

19

(0100 LT)

(2000LT)

(1700 LT)

Time of Day

Temperature


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Surface-Based Inversion Erosion with Time

d

Alt.

Time of Day

20

(0600 LT)

(0900 LT)

(1100 LT)

(1400 LT)

Temperature


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Cloud Base / Moisture Layers

  • T / DP Closure

    • Possible Cloud

    • Layers

  • Moist Adiabatic

  • Lapse Rate


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The Drying Process

Sinking, Heating

Drying

Moisture, Deficit

Air

10000 Ft MSL

Rising,Cooling

Condensing

5K Ft

Sierra

Nevada

White

Mtns

5000 Ft MSL

Owens

Valley

Great

Basin

MSL

San Joaquin Valley


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De-Stabilizing Process

Colder Air Advection above, and/or

Warm Air Advection below will de-stabilize

  • Delta-T increase!

  • Moisture presence

  • also de-stabilizes


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Basin Thunderstorm / Microbursts

  • Develop Adjacent cells

  • Classic short duration

  • 60Kt+ Sink Rates

  • Regardless of cell size

  • Wind shifts

  • Degrade ceiling and visibility


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Mojave Desert Downburst

Courtesy of Caracole Soaring, California City, CA)

25



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Thunderstorm Activity (#1)

  • Presence of "cap"; and "penetration" of cap (observed time vs. forecast time?)

  • Winds aloft

    • Cell movement

    • Anvil spread


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Thunderstorm Activity (#2)

  • Air mass Thunderstorms

    • Favored spots

  • Outflow



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N

Hook echo

Classic Supercell Thunderstorm

Light Rain

Moderate/Heavy Rain & Hail

Gust Front

Hook echo

Anvil Edge

Supercell Thunderstorm

(top view)

Nautical miles

10

5

0

WSR-88D Radar Image

30

National Weather Service www.weather.gov


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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)


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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


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Climate and Other Influences

  • Climate and Terrain Considerations

  • Modifying Influences and Contributions

  • Thunderstorm Indices


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Climate and Terrain

Great Basin

  • Time of year

    • Diurnal temperature spread

  • Humidity factors

  • Terrain rising aspects (and TAS)


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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)




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The Drying Process

Sinking, Heating

Drying

Moisture, Deficit

Air

10000 Ft MSL

Rising,Cooling

Condensing

5K Ft

Sierra

Nevada

White

Mtns

5000 Ft MSL

Owens

Valley

Great

Basin

MSL

San Joaquin Valley


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Major Modifying Influences(#1)

  • Washoe Zephyr

  • Nevada Sinks

  • Mono Lake Shear

  • Basin Air

  • Terrain "Holes"


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Major Modifying Influences(#2)

  • Topaz Flow

  • Mammoth Lakes

  • June Lake


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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!)


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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


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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


  • Thermal detractors l.jpg
    Thermal Detractors

    Macro-scale Level

    • <Cirrus Anvil from Thunderstorms

    • <Cirrus

      • Around jet stream cores

      • Small pressure perturbations / waves

  • <Convective Cloud Cover

    • More than 50% sky cloud cover

  • <Other

    • Relative Humidity gradients


  • Thermal enhancers l.jpg
    Thermal Enhancers

    Great Basin

    • <Rising terrain steps to southeast of Minden

      • Minden to Patterson/Bridgeport +2000'

      • Patterson to Whites +1000' and more

  • <Convergence / Shear

    • Mono Lake Shear Line

    • Flying “M” Shear Line

  • <Small air basins

    • Fixed volume of air to heat (valley vs. plain)

  • <Other

    • Summer wave or wave-encouraged cloud streets



  • Mono lake shear line l.jpg
    Mono Lake Shear Line

    • Mono Lake Shear Line

    • “Typically” present

    • Example: 6/13/99

    47




    Flying m shear line l.jpg
    Flying “M” Shear Line

    • Flying “M” Shear Line

    • “Typically” present

    • Example: 6/14/99

    50






    Mountain wave55 l.jpg
    Mountain Wave

    • Wave Presence for

    • Long Distance Flight

    • Example: 6/15/99

    55


    Moisture surges l.jpg
    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


  • East vs west great basin l.jpg
    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

    57


    Soaring f moisture changes l.jpg
    Soaring = f(Moisture Changes)

    Hypothesis: Annual Climate Changes Impact Soaring

    • 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

    58


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    Infrared Satellite Imagery

    • Cloud top temperature

    • Good delineator for high clouds


    Water vapor satellite imagery l.jpg
    Water Vapor Satellite Imagery

    • Moist and dry air boundaries

    • Active convection often along interface

    • Determine Raob representativeness of task area?


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    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


    Type 1 the four corner high l.jpg
    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


    Type 1 6 18 88 l.jpg
    Type #1: 6/18/88

    ASI to Keeler and return


    6 18 88 raobs l.jpg
    6/18/88 Raobs

    • WMC 94/50

    • RNO 90/58

    • TPH 83/52

    • LAS 98/78


    Type 2 strong ridge l.jpg
    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


    Type 2 8 9 96 l.jpg
    Type #2: 8/9/96

    Long-lived, extraordinary pattern

    Numerous 1000Km flights

    Over a 4-day period


    8 9 96 l.jpg
    8/9/96

    WMC 98/48RNO 95/53TPH 95/61LAS 99/80


    Type 3 low center trough or short wave proximity l.jpg
    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!


    Type 3 7 7 88 l.jpg
    Type #3: 7/7/88

    Flight of 350 miles


    7 7 88 raobs l.jpg
    7/7/88 Raobs

    <WMC 84/54

    <RNO 84/49

    <TPH 90/56

    <LAS 103/77


    Type 3 a proximity of low pressure center l.jpg
    Type #3(a): Proximity of Low Pressure Center

    <Low off Southern California coast provides cooler air aloft upstream to de-stabilize

    <Elevated heat source influence contributions


    Type 3 a 6 19 93 l.jpg
    Type #3(a): 6/19/93

    1000Km flights from Truckee

    And Minden area


    6 19 93 raobs l.jpg
    6/19/93 Raobs

    <WMC 86/47

    <RNO 88/57

    <TPH 86/54

    <LAS 94/72


    Type 4 building ridge aloft l.jpg
    Type #4: Building Ridge Aloft

    2 Examples / Next 4 Slides

    • <Temperature trend upward

      • Surface temps climbing faster than aloft

      • Subsidence not strong

      • Large diurnal temperature spread in transition

  • <Light wind aloft

    • Height gradient small

  • <Suppression of westerly washout


  • Type 4 6 13 88 l.jpg
    Type #4: 6/13/88

    500 Mile Flight


    6 13 88 raobs l.jpg
    6/13/88 Raobs

    <WMC 81/42

    <RNO 81/27 (!!!)

    <TPH 78/M

    <LAS 95/70



    4 weather forecasting l.jpg
    4. Weather Forecasting

    • Forecast Funnel

    • Soaring Indices

    • Automated Soaring Forecasts

      • Dr. Jack and BLIPMAP

      • Other Automated Forecasts

  • NWS IFPS (Gridded Data)


  • A glider pilot s forecast funnel l.jpg
    A Glider Pilot’s Forecast Funnel

    A Process of Soaring Forecast Refinement

    • Site Climate

    • Outlook Forecasts

    • Extended and Zone Forecasts (2-7 Day)

    • Persistence

    • Flight Day


    Soaring indices 1 l.jpg
    Soaring Indices(#1)

    Great Basin

    • Thermal Index

      • Lift = f()T)


    Soaring indices 2 l.jpg
    Soaring Indices (#2)

    Great Basin

    • Soaring Index

      • Lift = f(Convection Altitude and )T)


    Soaring indices 3 l.jpg
    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

      • 35+ excellent (too unstable many times)


    Instability indices 1 l.jpg
    Instability Indices(#1)

    Great Basin

    • K-Index

      • Uses Vertical Totals and 2 fixed reference levels

      • )T(C) + 850 dew point(C) - 700 dew point depression(C)

      • 5+ = some cumulus possibilities

      • Thunderstorms increase in the 10-15 range


    Instability indices 2 l.jpg
    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)


    Thermal lift indices work l.jpg
    Thermal Lift Indices Work

    • Thermal Index (Williams/Higgins)

    • Maximum Lift

      (Lindsay/Lacy)

    • Soaring Support (Aldrich/Marsh)

    • Soaring Index

      (Armstrong-Hill)

    85


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    Wave Strength Forecasting

    Wave Nomogram(Herold/Armstrong)

    86


    Traditional soaring forecasts l.jpg
    Traditional Soaring Forecasts

    • Persistence

    • Nowcasting

      • Soundings

      • Satellite

      • Analysis

    • Algorithm Use

    87


    Thermal index prediction tip dr john w jack glendening l.jpg
    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:http://www.drjack.net/TIP/index.html

    URL:http://www.drjack.net/TIPEX/index.html

    88


    Boundary layer information predictor maps blipmap l.jpg
    Boundary Layer Information Predictor Maps(BLIPMAP)

    • Thermal Soaring Parameters (over a geographic region)

    • -Numerical Model Outputs

    • General Air Mass Lift

    • Single Time or Sequence

    • URL:www.drjack.net/BLIPMAP/index.html

    89


    Wind information predictions windip l.jpg
    Wind Information Predictions (WINDIP)

    (Simple Mountain Wave Prediction)

    • “Alert” WINDIP E-Mail List

    • Assumptions

    • Longer Forecast Time Predictions

    • URL:http://www.drjack.net/WINDIP/index.html

    90


    Linear wave interpretation page lwip l.jpg
    Linear Wave Interpretation Page (LWIP)

    • Description

    • Interpretation

    • Notes

    • Links

    URL:http://www.drjack.net/LWIP/index.html

    91


    Automated thermal soaring forecasts l.jpg
    Automated Thermal Soaring Forecasts

    Walt Rogers (WX), MIC CWSU ZLA

    • Two Parts:

      1.Pure Model Output (top portion)

      2.NWS Forecast Temps as base (lower portion)

    • Limitations

    • NWS Websites

    URL:http://www.weather.gov/*****

    where ***** is NWS Office Name, I.e., Hanford, Oxnard, etc.

    92


    Interactive forecast preparation system ifps l.jpg
    Interactive Forecast Preparation System (IFPS)

    • “Flagship” Products Not Text

    • -Forecasters Edit Gridded Data

    • Graphical Products

    • -Customer Requested Output

    • Man-Machine Mix

    93


    Gridded data l.jpg
    Gridded Data

    Graphical Display of Requested Weather Parameter(s)

    94


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    5. Miscellaneous Information

    • Aero-medical Considerations


    Aeromedical considerations l.jpg
    Aeromedical Considerations

    Soaring good enough that...

    <Oxygen requirements

    <Water

    <Sun protection


    Meteorological concepts for soaring in the western u s97 l.jpg
    Meteorological Concepts for Soaring in the Western U.S.

    Dan Gudgel

    Meteorologist/Towpilot/CFIG

    134 South Olive Street

    Lemoore, CA 93245

    (w)559-584-3752 ext.223

    (h)559-924-7134

    <[email protected]>


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