Aviation User Training TAF Interpretation and Supplemental Products

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 06 z Monday – 00 z Saturday - 06 z Monday • Every 2 hours starting at 06 z Monday • Unscheduled AMD’s as needed • 00, 06, 12, 18 z issued 20 -40 min prior • Scheduled AMD’s issued around top of the hour • Every 3 hours starting at 00 z Saturday • Unscheduled AMD’s as needed • 00, 06, 12, 18 z issued 20 -40 min prior • Scheduled AMD’s issued around top of the hour

TAFs • Forecast for conditions within 5 SM 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

PROB 30 • 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 (BKN 030 CB) • 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

Getting the Most From the TAF INTERPRETATION

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 Indicates –TSRA may be developing SHRA/TSRA between 5 and 10 SM from the airfield TAF >50% chance of occurrence <50% of the TEMPO period KORD 231740 Z 2318/2424 15012 KT P 6 SM SCT 040 CB FM 232100 16012 KT P 6 SM VCSH BKN 040 CB TEMPO 2322/2324 30024 G 50 KT 1 SM TSRA BKN 030 CB OVC 050 FM 240000 30010 KT P 6 SM –SHRA BKN 040 CB FM 240200 30010 KT P 6 SM SCT 040

Trends Among Successive TAFs

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

Additional Information: THE AVIATION FORECAST DISCUSSION

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 • •

Additional Information: VALUABLE SEASONAL PRODUCTS

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