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Aviation Hazard Awareness Training – Volume I Thunderstorms Jody James, Senior Forecaster

Aviation Hazard Awareness Training Jody James Senior Forecaster Private Pilot NWS Lubbock

Aviation Hazard Awareness Training Mission of National Weather Service: The National Weather Service ™ (NWS) provides weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas, for the protection of life and property and the enhancement of the national economy. NWS data and products form a national information database and infrastructure which can be used by other governmental agencies, the private sector, the public, and the global community. "

Our Operation’s Area Aviation Hazard Awareness Training

We Will Cover: Motivation for Avoidance Motivation for Avoidance Types of Weather Associated with T-stms Types of Weather Associated with T-stms NWS Aviation Products NWS Aviation Products Gathering Pre-flight and In-flight data Gathering Pre-flight and In-flight data Common Sense Principles Common Sense Principles

Accident Statistics 2004 Joseph T. Nall Report Accident Trends and Factors for 2003

Accident Statistics *From AOPA ASF 2003 Nall Report General Aviation is still safe… and getting safer!

Weather Accident Statistics General Aviation is still safe… and getting safer! BUT… We can do better! *From AOPA ASF 2003 Nall Report

Nall Report Accident Statistics *From AOPA ASF 2003 Nall Report  Weather related accidents accounted for 13.6% of all fatal pilot-related accidents  (67%) weather related accidents involved fatalities. (single engine fixed gear)  Attempted VFR flight into IMC" continues to be the most deadly weather-related accident cause. In 2003, two-thirds of all fatal weather-related accidents were a result of VFR into IMC.  “The majority of accidents are in takeoff and landings, and the majority of fatalities are due to maneuvering and weather encounters.”

What is a Thunderstorm? Rapidly rising column of air Warmer than the surrounding air Produces Lightning May produce heavy rain, hail and much more!

Thunderstorms More common in the warm season Very dangerous to aviation Should be avoided!!

Mechanisms of T-stm Development

Cold Front

Mechanisms of T-stm Development Dry Line

Mechanisms of T-stm Development Others Upper Low Sea Breeze Orographic Flow (over mountains) Daytime Heating

Kinds of Thunderstorms

NWS Definition of Severe Meets one or more of the following criteria… ¾ inch diameter hail or larger 50 knot or greater sustained winds Tornado (or possible Tornado) NWS SEVERE THUNDERSTORM WARNING

Why Avoid Thunderstorms? Severe or Extreme Turbulence Severe Icing Low Level Wind Shear (Mechanical) Microbursts (Convective LLWS) IFR or LIFR Conditions Strong surface winds…30 knots or greater And as we have already seen…weather related accidents have a much higher probability of being fatal!

Avoid By How Much?

20 miles!!

What is Turbulence? Air currents that vary greatly over short distances, these may range from mild eddies that cause bumpiness…to strong currents of relatively large dimensions that can structurally damage an aircraft or injure its passengers.

Where is the Turbulence? Visible thunderstorm is only a portion of the turbulent area. Severe turbulence can be 20 miles from the visible part of a severe thunderstorm! …around 10 miles or less from a non severe thunderstorm.

Rules of Thumb – Turbulence Turbulence is directly proportional to: Speed of the aircraft. Wing area Turbulence is inversely proportional to: Weight of the aircraft Smaller aircraft benefit from slower speeds and smaller wing areas…but that is offset by a lighter weight! That is why what is light turbulence by 737 Captain may be described as moderate turbulence in a Piper Cherokee!

Where in the Thunderstorm? There is some evidence that the maximum turbulence exists at the mid levels of the storm. Recent studies however show little variation of turbulent intensity with altitude!

Frequency and Severity of Turbulence Generally increases with radar reflectivity, which is closely associated with the highest liquid water content of the storm. Area of greatest turbulence

Be Careful Punching Cores! No flight path through an area of strong or very strong echoes separated by 2 miles or less may be considered free of … SEVERE TURBULENCE! Area of greatest turbulence From FAA Aeronautical Information Manual c.

High Based Thunderstorms Dry air beneath a thunderstorm base (or between surface and 15,000 feet) may result in lower altitudes being characterized by strong outflow winds and severe turbulence.

The Microburst Precipitation induced downdraft which can produce winds to 100 knots or greater. Has caused numerous airline crashes through the years including Delta Flight 191 an L-1011 on August 2, 1985 at DFW Airport. Cross section of vortex ring model (Caracena, 1982)

The Microburst Typical appearance of a microburst on Doppler radar as observed during the Joint Weather Studies Project. (Photograph by John McCarthy, National Center for Atmospheric Research/National Science Foundation.)

The Microburst Dry Microburst forming under prominent virga shaft. Note ring of dust beneath rain shaft. (Photograph by E. Szoke, 14 July 1982, National Center for Atmospheric Research/National Science Foundation.)

The Microburst Photos ©1991 William Bunting. Downburst Animation

Gathering Data… Pre-flight planning to avoid Thunderstorms Monitor Forecast Maps Several Days in Advance Weather Channel Internet Graphics, etc…

Aviation Weather Center The Aviation Weather Center website is a great website for standard briefing products…such as Convective Sigmets…METARS…TAFS…Area Forecasts from the folks who write the national aviation products. Experimental Products Icing conditions…mountain wave turbulence and more CCFP

Excellent Source for Online Weather Information…and it’s free! The ADDS (aviation digital data service) website contains forecasts and graphics with this data: TurbulenceIcingWind/Temps Aloft METARS/ TAFS PIREPSSIGMETS/ AIRMETS RadarSatelliteProg Charts

Excellent Source for Online Weather Information…and it’s free! The Aviation Digital Data Service (ADDS) is a joint effort of NOAA Forecast Systems Laboratory (FSL), the National Center for Atmospheric Research (NCAR), and the NWS Aviation Weather Center (AWC). Website Address:

Gathering Data… Pre-flight planning to avoid Thunderstorms Monitor Storm Prediction Center (SPC) for Day 1… Day 2 and Day 3 Convective Outlooks This will outline areas where severe and non-severe convection are possible (next 3 days) according to the severe weather experts at the Storm Prediction Center…

Gathering Data… Pre-flight planning to avoid Thunderstorms Before departing for airport…check radar imagery…satellite imagery…latest pireps and Convective Sigmets! NWS Nexrad imagery is available now in real time on the internet.

What Will A Thunderstorm Look Like… Ordinary or Non-Severe Thunderstorm KLBB Z G25KT P6SM SCT050 TEMPO 2124 VRB20G40KT 2SM TSRA OVC030CB Severe Thunderstorm KLBB Z G30KT P6SM BKN100 TEMPO 0204 VRB30G50KT 1SM +TSRAGR OVC015CB in a TAF?? Terminal Aerodrome Forecast

Question?? Severe Thunderstorm KLBB Z G30KT P6SM BKN100 TEMPO 0204 VRB30G50KT 1SM +TSRAGR OVC015CB Is the above TAF indicating the possibility of: A microburst or downburst? or Low level wind shear?

Differentiating between Low Level Wind Shear and Thunderstorm Outflow (such as Microbursts or Downbursts) Downbursts are small scale…associated with thunderstorms…and are a short lived and very localized phenomenon… TAF: VRB30G50KT 1SM +TSRAGR OVC015CB

Differentiating between Low Level Wind Shear and Thunderstorm Outflow (such as Microbursts or Downbursts) Low Level Wind Shear (nonconvective) occurs on a large scale…and is typically associated with a Low Level Jet. LLWS is a longer lived and more widespread phenomenon. TAF: FM KT P6SM SCT020 OVC035 WS010/23050KT

What You See Is What You Get… Always be prepared to answer the START/CONTINUE question as well as GO/NO? The Pre-flight information that you looked at earlier is “old news”. You will verify the accuracy of the forecast!!

Evaluating In-flight data to avoid Thunderstorms Maintain VFR Conditions to avoid buildups Avoid Towering Cumulus and T-stms by 20 miles! Monitor Flight Watch on Monitor on-board radar or Stormscope (remember limitations) Beware of embedded storms Do not fly beneath a strong t-stm or try to beat a t-stm to your destination. NWS Nexrad imagery is available now in real time on the internet.

Increasing Situational Awareness The GPSMAP 396 with XM WX Satellite Weather™ features: Radar METARS TFR’s, Lightning Winds Aloft In addition to: Topography Traffic Alerts Flight Information

If You Get Caught… in A Thunderstorm? KEEP YOUR COOL! Slow to Maneuvering Speed Va Tighten Seat Belts Fly Attitude…Not Altitude Ask ATC for Block Altitude Do Not Turn around! Could result in Excessive G-loads…Unusual attitudes

We Need Pireps!! The Best Source for Actual Weather Information is You!! Accurate and timely Pireps help pilots make better weather decisions and help meteorologists make better forecasts! The Skyspotter program is co-sponsored by AOPA Air Safety Foundation…the FAA…and the NWS Aviation Weather Center. Becoming a Skyspotter and give at least one Pirep on each flight.

We Need Pireps!! "From the DC-2 and 3 era when we worried about ice over the Pennsylvania mountains, to the 747 over the ocean when someone ahead warns of turbulence, pilot reports have been an integral part of flying; hearing what the ceiling really will be on approach, where the ice is, what the tops and bases are, how the braking action is and a host of other things from another pilot is part of what bonds flying people together — and helps save our hides. Tell what's out there so the next person can cope with it." — Captain Bob Buck TWA, retired

We Need Pireps!! Here’s How… WHO…Piper Cherokee WHAT…Overcast Layer…base 4,500’, top 6,000’, light rain, moderate turbulence, temperature 10 deg. C WHEN10 minutes ago WHEREOver Lubbock at 9,500’ Report to FSS or Flight Watch on 122.0

Aviation Hazard Awareness Training – Volume I Summary Know Your Enemy - Thunderstorms. Get as much information as you can – before and during the flight! Best Possible Strategy – Avoidance!! FLY SAFELY!!

Aviation Hazard Awareness Training – Volume I Favorite Aviation Tidbits Jody James, Senior Forecaster Flying is not dangerous; crashing is dangerous. A thunderstorm is never as bad on the inside as it appears on the outside. It's worse! The probability of survival is equal to the angle of arrival. Flying is the perfect vocation for a man who wants to feel like a boy, but not for one who still is.

Aviation Hazard Awareness Training – Volume I Jody James, Senior Forecaster