Southwest Aviation Weather Safety Workshop Salt River Project Phoenix, AZ April 10-11, 2007

Aviation Hazard Awareness Training 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. "

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 2006 Joseph T. Nall Report Accident Trends and Factors for 2005

Accident Statistics *From AOPA ASF 2006 Nall Report General Aviation is still safe… but we still need to improve!

Accident Statistics *From AOPA ASF 2006 Nall Report Weather Accidents comprised only 4.6 percent of accidents, but 1 out of 6 (13.6 percent) fatal accidents

Weather Accident Statistics Thunderstorms rank 2 nd in Weather Related accident causes 1 st was VFR into IMC. *From AOPA ASF 2006 Nall Report

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

Why Avoid Thunderstorms? Severe or Extreme Turbulence Severe Icing Low Level Wind Shear (Convective) 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!!

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!

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 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.)

Gathering Data… Pre-flight planning to avoid Thunderstorms Monitor Forecast Maps Several Days in Advance AWCInternet Graphics, etc… Official Briefing Flight Service

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

The Aviation Digital Data Service (ADDS) makes available to the aviation community text, digital and graphical information. ADDS is a joint effort of NCAR Research Applications Program (RAP), Global Systems Division (GSD) of NOAA's Earth System Research Laboratory (ESRL), and the National Centers for Environmental Prediction (NCEP) Aviation Weather Center (AWC).RAPGSDESRLNCEPAWC

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 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.

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!! 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 Jody James, Senior Forecaster