1. Aviation User Training: TAF Interpretation and Supplemental Products

2. Outline TAF Basics TAF Definitions and Limitations TAF Interpretation-reading into the TAF Supplemental Products Links

3. 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

4. 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

5. DEFINITIONS AND LIMITATIONS

6. FM – From Groups A new FM group indicates a significant change in prevailing conditions >50% probability of conditions occurring

7. 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

8. PROB30 30% chance of occurrence Cannot be used in the first 9 hours of the valid TAF period

9. 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

10. 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

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

12. 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

13. TAF INTERPRETATION Getting the Most From the TAF

14. 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

15. Trends Within A TAF TAF KORD 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 developing SHRA/TSRA between 5 and 10 SM from the airfield >50% chance of occurrence <50% of the TEMPO period

16. Trends Among Successive TAFs

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

18. THE AVIATION FORECAST DISCUSSION Additional Information:

19. 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

21. VALUABLE SEASONAL PRODUCTS Additional Information:

22. Warm Weather Tips Four Product Approach – TAF – Aviation Forecast Discussion – Thunderstorm Tactical Decision Aids – CCFP

23. 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?

24. 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

25. 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

26. Alternate TS TDA

27. 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

28. Winter Weather Tips Four Product Approach – TAF – Aviation Forecast Discussion – ORD Winter Precipitation Outlook – Winter Weather Headlines (watches/warnings/advisories)

29. Experimental O’Hare Winter Precipitation Outlook -November 1-March 31 -5 am, 11 am, 5 pm local time -No updates between issuances

30. Winter Weather Headlines

31. Links Add latest links here

32. Questions?? Scott Shelerud