Aviation User Training: TAF Interpretation and Supplemental Products

Outline

• TAF Basics• TAF Definitions and Limitations• TAF Interpretation-reading into the TAF• Supplemental Products• Links

TAF Issuance Times

06z Monday – 00z Saturday• Every 2 hours starting at 06z

Monday• Unscheduled AMD’s as

needed• 00, 06, 12, 18z issued 20-40

min prior• Scheduled AMD’s issued

around top of the hour

00z Saturday - 06z Monday• Every 3 hours starting at 00z

Saturday• Unscheduled AMD’s as

needed• 00, 06, 12, 18z issued 20-40

min prior• Scheduled AMD’s issued

around top of the hour

TAFs

• Forecast for conditions within 5SM of the center of an airport

• Valid for 30 hrs at ORD and 24 hrs at MDW, RFD, DPA, GYY

DEFINITIONS AND LIMITATIONS

FM – From Groups

• A new FM group indicates a significant change in prevailing conditions

• >50% probability of conditions occurring

TEMPO

• >50% probability of occurrence and,• Last for 1 hour or less in each instance and,• Cover less than half the time period of the

TEMPO group• May not last long or may be intermittent

PROB30

• 30% chance of occurrence• Cannot be used in the first 9 hours of the valid

TAF period

VC – Vicinity

• Donut shaped area between 5 and 10 SM from the center of the airport

• Used when there is a >50% probability of occurrence within the donut and it is expected to occur more than half of the forecast time period

• A prevailing condition in the 5-10 SM donut• VCTS, VCSH, VCFG

CB

• Appended to the cloud group (BKN030CB)• May be included without TS• Indicates TS is possible but: – It is NOT certain it will occur at the airport or in

the vicinity

Available Probabilities

• >50%• <50% (if we don’t include something)• 30%...but only beyond the first 9 hours• Lots of room for interpretation!!

TAF Challenges

• Complex definitions• Rigid format with little room to convey specific

uncertainty or confidence• However…there is more information available

and there are ways to better utilize the TAF

TAF INTERPRETATIONGetting the Most From the TAF

The Trend is Your Friend

• Look for trends within each TAF• Look for trends in successive TAFs (can you access

earlier versions?)

– Can indicate our confidence level in the forecast– Can establish if chances for occurrence are

increasing or decreasing• Unscheduled amendments indicate a high

degree of confidence in forecast changes

Trends Within A TAF

TAFKORD 231740Z 2318/2424 15012KT P6SM SCT040CB FM232100 16012KT P6SM VCSH BKN040CB TEMPO 2322/2324 30024G50KT 1SM TSRA BKN030CB OVC050 FM240000 30010KT P6SM –SHRA BKN040CB FM240200 30010KT P6SM SCT040

Indicates –TSRA may be developingSHRA/TSRA between 5 and 10 SM from the airfield

>50% chance of occurrence <50% of the TEMPO period

Trends Among Successive TAFs

Accessing Previous TAFs

http://www.crh.noaa.gov/lot/?n=aviation

THE AVIATION FORECAST DISCUSSION

Additional Information:

Aviation AFD

• Your window into the forecasters’ mind• Updated with every scheduled TAF issuance• Use side-by-side with the TAF• Specifically outlines concerns for ORD/MDW

and provides level of forecast confidence• May also include alternative scenarios for

lower confidence or lower probability situations

VALUABLE SEASONAL PRODUCTSAdditional Information:

Warm Weather Tips

• Four Product Approach– TAF–Aviation Forecast Discussion– Thunderstorm Tactical Decision Aids–CCFP

Our Approach to Forecasting Thunder

1. What is the trigger (cold front, trough…)?2. How much coverage should we expect with

this type of trigger?3. How long does TS usually last with this type of

setup?4. How confident are we that TS will occur?

(what mitigating factors are there?)5. What is the most likely time window for

occurrence?

Conveying Confidence

• CB– can be used to indicate the presence of CB’s– hints at the possibility of TS

• VCTS– prevailing TS in the 5-10 mile donut around the

terminal– used when coverage is scattered/or storms

skirting by and/or there is uncertainty that the terminal will be directly affected

TS TDA

• TS probability at key arrival and departure points

• Does not show TS chances at the terminals or areas between the terminals and the gates

• Frequently updated

Alternate TS TDA

CCFP

• Designed for the en route environment; strategic planning of efficient routes

• Too coarse for use in the terminal area• Can be used to help establish confidence in

potential for TS occurrence in the general area near terminals

Winter Weather Tips

• Four Product Approach– TAF–Aviation Forecast Discussion–ORD Winter Precipitation Outlook–Winter Weather Headlines

(watches/warnings/advisories)

Experimental O’Hare Winter

Precipitation Outlook

-November 1-March 31-5 am, 11 am, 5 pm local time-No updates between issuances

Winter Weather

Headlines

Links

• Add latest links here

Questions??

Scott Shelerud