1. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 1 June 26, 2007 IMPACT OF TAMDAR DATA ON RUC SHORT-RANGE FORECASTS Ed Szoke*, Randy Collander*, Brian Jamison*, Tracy Smith* Stan Benjamin, Bill Moninger, Tom Schlatter**, and Barry Schwartz NOAA/Earth Systems Research Laboratory Global Systems Division *Joint collaboration with the Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO **Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, Colorado

2. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 2 June 26, 2007 Overview TAMDAR soundings have been shown to be useful for forecasting Talks at the last SLS Conference and previous Annual Meetings WFO Green Bay helps maintain the official NOAA TAMDAR web page at http://www.crh.noaa.gov/tamdar/ In this talk we focus on the impact on NWP: Evaluation of RUC precipitation forecasts for runs with and without TAMDAR for significant weather events Mostly a subjective evaluation, but objective scoring for 2007 cases Procedure: RUC is run at 20-km horizontal grid resolution Identical runs made hourly to 6 h, and out to 24 h every 3 h Here we will concentrate on shorter term (usually first 6 h to 12 h) forecasts initialized when TAMDAR data is most plentiful 1800 UTC and 0000 UTC initialization times generally used

3. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 3 June 26, 2007 Flights into a number of smaller airports in addition to the 3 main hubs And at lower altitudes (generally to 20 kft or so) Typical TAMDAR coverage (shown here 1000 UTC/18 Oct – 0400 UTC/19 Oct 06)

4. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 4 June 26, 2007 Verification areas. Objective scoring is done on both areas, for this study we will show some scores for the inner (blue) box.

5. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 5 June 26, 2007 Still one of the most dramatic cases...4-5 Oct 2005: heavy precip in the Upper Midwest. Flooding reported in Minnesota to northern Wisconsin. Case 1: 4 October 2005 – 2100 UTC Surface analyses and reflectivity

6. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 6 June 26, 2007 Very sharp cut off to the precip in WI and a huge gradient with a 2-3” max. NPVU estimated precipitation for 6-h ending 0000 UTC 5 October 2005

7. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 7 June 26, 2007 Both runs forecast too much precip in southern half of Wisconsin, but the RUC run with TAMDAR correctly forecasts more precip (small spots of >1.00”) across the northern half of the state. RUC forecasts from the 4 October 2005 1800 UTC runs 6-h total precipitation ending 0000 UTC 5 October

8. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 8 June 26, 2007 Sounding comparison: RUC 6-h forecasts with (labeled dev2) and without (labeled dev1, in black) TAMDAR, compared to the RAOB for Detroit (green) at 0000 UTC 5 Oct 05. Incorrect dry layer in the dev1 forecast.

9. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 9 June 26, 2007 Same comparison but for Peoria, Illinois. The RUC run with TAMDAR is closer to the RAOB especially at and below 700 mb.

10. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 10 June 26, 2007 Heavy precip continues in the same areas Case 1/part 2: 5 October 2005 – 0300 UTC Surface analyses and reflectivity

11. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 11 June 26, 2007 NPVU estimated precipitation for 6-h ending 0600 UTC 5 October 2005

12. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 12 June 26, 2007 For this period the RUC run that used the TAMDAR data is a much better forecast with a very sharp cut off to the precipitation in Wisconsin and a better location for the heavy precip. RUC forecasts from the 5 October 2005 0000 UTC runs 6-h total precipitation ending 0600 UTC 5 October No TAMDARWith TAMDAR

13. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 13 June 26, 2007 Case 2: 20 January 2006 – 2100 UTC Surface analyses and reflectivity

14. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 14 June 26, 2007 This event impacted an extensive area with winter precipitation Power outages from portions of Iowa to Illinois where snow became freezing rain

15. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 15 June 26, 2007 About 5” of snow at O'Hare Airport in Chicago, but a foot just to the northwest. Observed snowfall ending ~1200 UTC 21 January 2006

16. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 16 June 26, 2007 Most of the snow fell in the 12-h period ending at 0600 UTC, so can compare the amounts observed to the RUC 12-h snowfall forecasts below.

17. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 17 June 26, 2007 Sounding comparison as before: RUC 6-h forecasts with (labeled dev2) and without (labeled dev, in black) TAMDAR, compared to the RAOB for Green Bay (green) at 0000 UTC 21 Jan 06. dev2 is closer to the observed sounding.

18. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 18 June 26, 2007 Similar comparison for Peoria, Illinois. Not much difference in these forecasts

19. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 19 June 26, 2007 Precipitation comparison. NPVU estimated precipitation for 6-h ending 0600 UTC 21 January 2006

20. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 20 June 26, 2007 The RUC run with TAMDAR did a better job of forecasting more precipitation in central Illinois. RUC forecasts from the 21 January 2006 0000 UTC runs 6-h total precipitation ending 0600 UTC 21 January

21. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 21 June 26, 2007 Case 3: 13 February 2007 – 1800 UTC Surface analyses and reflectivity

22. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 22 June 26, 2007 Case 3: This was a high-impact event with huge area of winter weather watches and warnings and even a blizzard warning, plus severe weather

23. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 23 June 26, 2007 Forecasts are pretty close in the snow area (as verified by the objective scoring), but there are some differences farther to the south in the convection ahead of the trailing cold front. RUC forecasts from the 13 February 2007 1800 UTC runs 6-h total precipitation ending 0000 UTC 14 February

24. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 24 June 26, 2007 NPVU estimated precipitation for 6-h ending 0000 UTC 14 February 2007

25. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 25 June 26, 2007 TAMDAR coverage for the period 1500 to 1800 UTC on 13 February 2007 Why the similar forecasts in the snow area? Maybe a lack of TAMDAR because of flights canceled by the storm! TAMDAR coverage for the period 1500 to 1800 UTC on 15 February 2007 when conditions were dry in the region.

26. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 26 June 26, 2007 Note the similar forecast soundings for Pittsburgh (6-h forecasts ending at 0000 UTC 14 February with the RAOB).

27. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 27 June 26, 2007 Not the case for this same sounding comparison at Nashville, Tennessee. Overall, the sounding from the run using TAMDAR (dev2) is closer to the RAOB. The RUC run with TAMDAR had a better forecast in the central Tennessee

28. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 28 June 26, 2007 Perplexing comparison for Detroit, however, where there was abundant TAMDAR for this day.

29. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 29 June 26, 2007 Case 4: 22 March 2007 – 0000 UTC Surface analyses and reflectivity Strong spring storm with lots of severe weather

30. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 30 June 26, 2007 22 March 2007 – 0300 UTC Surface analyses and reflectivity

31. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 31 June 26, 2007 SPC severe reports for 24-h ending 1200 UTC/22 March 2007

32. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 32 June 26, 2007 Some differences are seen – these are outlined in the forecasts The RUC forecast that uses TAMDAR is generally better except within the orange oval area, where no precipitation fell. RUC forecasts from the 22 March 2007 0000 UTC runs 6-h total precipitation ending 0600 UTC 22 March No TAMDARWith TAMDAR

33. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 33 June 26, 2007 NPVU estimated precipitation for 6-h ending 0600 UTC 22 March 2007

34. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 34 June 26, 2007 The statistics agree with the subjective assessment favoring the RUC run that uses the TAMDAR data. Objective scores for the two RUC forecasts for the small verification area and for the 6-h period ending at 0600 UTC/22 March 2007

35. AMS 22 nd Conference on Weather Analysis and Forecasting/18 th Conference on Numerical Weather Prediction - 2007 – Park City, Utah 35 June 26, 2007 Summary When we began to examine precipitation forecasts in late 2005 were impressed by the 4-5 October 2005 case with significantly better forecasts by the RUC run that used TAMDAR But that remains our best case More typically, we see much smaller impacts These tend to favor the RUC run that uses TAMDAR, but not always And sometimes mixed...forecast better in some spots but not in others Objective scoring of the precipitation forecasts that began in 2007 agrees with our overall subjective impression Long-term statistics are not likely to show notable differences But on a case by case basis can see differences in the scores