NWS Pocatello Aviation Forecast Operations Gary Wicklund Aviation Meteorologist

NWS PocatelloAviation Forecast

Operations

Gary WicklundAviation Meteorologist

My 42 Year Forecast Method

Forecast Office Overview

• 5 Lead Forecasters• 5 Journey Forecasters• 3 Hydro-Met.Techs. / Intern

Our Responsibilities include:

• Public Forecasts and Warnings• Hydrologic• Wildfire and Land Management• Avalanche Guidance• Aviation Our Operational Staff includes:

Responsible for southeast Idaho

Aviation Operations Overview

Terminal Aerodrome Forecasts (TAFs)

Four times a day and updated as needed

Pocatello Idaho Falls Sun Valley Burley

What We Do…

Forecast Office Support, as needed, to:

Boise Salt Lake City

Weather FundamentalsCirculation: Earth’s orbit and axis tilt create our seasons

Weather FundamentalsAir rises higher at Equator than poles

Weather Fundamentals• Different air masses which affect North America, as well as

other continents, tend to be separated by frontal boundaries• Source regions of global air masses (cA, mP, etc.)

Weather Fundamentals

Clouds and stability– Stable air mass -- flat cloud development – Unstable air mass -- vertical growth


Cloud Classification

• Stratus: “layered”, “sheetlike”

• Cumulus: “puffy”, “heap”

• Nimbus: “rain cloud” or “violent rain”

• Cirrus: “wispy” type of cloud


Low Cloud Type - Cumulus

“Cotton ball” clouds

The top of the cloud generally denotes the limit of the rising air.

Clouds are “detached”, with blue sky between each cloud


Low Cloud Type – Fair Weather Cumulus


Low Cloud Type - Towering Cumulus


Mature Thunderstorm


Mature Thunderstorm Possibilities Dry Microburst / Tornado


Microburst Threat



Mt Shasta

Mt FujiMt Rainier

Teton Range

Lenticular CloudsWeather Fundamentals

Lenticular Clouds - Mountain WavesWeather Fundamentals

Danger? Vertical rises of over 15 Ft/sec with Mountain Waves

Cloud Type – Altocumulus


Cloud Type - High Clouds


Weather Fundamentals• Clouds can indicate the type of approaching front

X

• Cold air is approaching and clouds are very close to front

Cold Front

XObserver



Atmospheric Inversion

Fog

Horizontal Motion (Advection)– Moist air passes over a cool surface – Well known area is in the San Francisco Bay

Radiational Cooling– Moist air mass cools near the ground to the point of

condensation causing fog to form– Generally you need calm winds and clear skies



• How weather Fronts are Defined


Local Hazards

Dense Fog (especially Nov – Mar) Low Clouds and/or Visibility Mountain Obscurations

In the Winter months…In the Winter months…

In the Summer months… Thunderstorms, with hail and/or high winds

Local Hazards

Ice & SnowIce & Snow

Local Hazards

Strong WindsStrong Winds

Local Hazards

Mountain ObscurationsMountain Obscurations

Thunderstorms and LightningLocal Hazards

Low Level Wind ShearDanger? Stalls and abrupt landings

Vertical Wind Shear 10 knots or more per 100 feet in a layer at least 200 feet thick

Must be within 2000 feet of Ground

PIREP reporting non-convective wind shear causing an airspeed loss/gain of 20 knots (within 2000 feet of ground)

What Is It?

West winds at Sun Valley in gap to West of Tower

Likely with…

Terminal Aerodrome Forecast

A detailed weather forecast for the next 24 hours

Valid for a 5 mile radius from the center of any airport

Elements include Visibility, Cloud Heights, Winds, and Weather

Issued daily at 00Z, 06Z, 12Z, and 18Z

May include Low Level Wind Shear

What is a TAF?

Example:

KSUN 131741Z 1318/1418 10013KT P6SM OVC060 FM140100 10012KT P6SM SCT040 OVC070 TEMPO 1402/1406 -RA FM140600 17014KT P6SM -RA BKN040 OVC070 FM141200 21005KT P6SM SCT025 BKN045=

Current METAR for KPIH reported at: Apr 7 2010, 8:53 am MDT

KPIH: 071453Z 22009KT 10SM CLR 02/M04 A3037 RMK AO2 SLP300

T00171039 53009

TAF: KPIH 071120Z 0712/0812 22007KT P6SM SKC

FM071800 24012G18KT P6SM SCT200

FM080200 VRB05KT P6SM SCT200

Metar Observation

Pilot Reports

Forecasters!

Fellow Pilots!

Anyone with a flying interest

PIREPs often are the first sign of trouble, or weather to affect routes/airport terminals

REMEMBER, your PIREP is extremely valuable.

Who Needs Them?

Example:GEG UA /OV GEG 180008 /TM 2246 /FL 150 /TP PAY2 /SK OVC-TOP012/OVC160 /TA M07 /WV 23040KT /TB LGT OCNL MOD

AIRMET TANGO UPDT 2 FOR TURB VALIDUNTIL 082100 AIRMET TURB...NV OR CA AND CSTL WTRS FROM50NW LKV TO BAM TO 30W LAS TO 20E MZB TO 220SWMZB TO 140WSW FOT TO 150NW FOT TO 50NW LKV MOD TURB BTN FL230 AND FL410. CONDS CONTG BYD 21Z THRU 03Z. OTLK VALID 2100-0300Z AREA 1...TURB NV CA AND CSTL WTRS BOUNDED BY 20ENE BAM-20E OAL-40NW RZS-150WSW RZS-140SW PYE-SNS- 20ENE BAM MODTURB BLW 140. CONDS CONTG THRU 03Z.AREA 2...TURB NV UT AZ OR CA BOUNDED BY 50NW LKV-20NNW REO-20ESE ILC-80WSW TUS-BZA-20ESE MZB- 30W LAS-BAM-50NW LKV MOD TURB BTN FL230 AND FL410. CONDS CONTG THRU 03Z.

AIRMETs

Areas of Moderate Turbulence

Areas of Moderate Icing and freezing levels

Areas of IFR Conditions and mountain obscurations

Strong Convective Areas

Volcanic Ash Tracks

Issued at 13Z, 19Z, 01Z, & 07Z -- Updated as needed

Issued by National Aviation Center in KCMO

SIGMETs

Thunderstorms greater than (33 dBZ) affecting 40% or more of a 3000 square mile area Line(s) of Thunderstorms

Isolated Severe Thunderstorms (3/4” hail and/or 50 knot winds)

Tornadoes

Embedded Thunderstorms

Volcanic Ash

Issued when needed

WSUS31 KKCI 081955SIGECONVECTIVE SIGMET...NONEOUTLOOK VALID 082155-090155TS ARE NOT EXPD.

Issued by National Aviation Center in KCMO

Upper Air Winds

Where to get Weather Information

• Information Sources- Pilot Weather Briefings @ 1-800-WEATHER

- Internet

-- ADDS – Aviation Weather

-- DUATS

-- Salt Lake City Center Weather Service Unit

-- Weather Forecast Office, Pocatello

-- AIM

-- AOPA

Where to get Weather Informationadds.aviationweather.gov

Where to get Weather informationwww.wrh.noaa.gov/zlc

www.weather.gov/pocatello

ForecastsActivity PlannerSoutheast IdahoDiscussionAviationFire WeatherHydrologyAvalancheRecreationGraphicalOutlooks

Where to get Weather information

Weather and Accidents

Source: NTSB chairman, Jim Hall’s testimony before the Committee on Transportation and Subcommittee on Aviation (22 July 1999)

National Transportation Safety Board Statistics… 33% of all FATAL accidents are weather related

Of these, 40% occur within the TAF area of the airport

Low Ceilings and/or Visibilities

Icing

Thunderstorms, Lightning and/or Hail

Low Level Wind Shear

Main Weather with these Crashes…

Weather Forecast Office Pocatello

Questions?

Thank You.

Documents

NWS Pocatello Aviation Forecast Operations Gary Wicklund Aviation Meteorologist