1. February 6, 2012 Verification Western California Dan Tomaso, Tyler Roys, & Brian Clavier

2. HPC Analysis, Monday 2/6 12z

3. Forecast Concerns- Timing

5. Forecast Concerns- Terrain/P-Type

6. Forecast Concerns- Previous Day Warming due to compression with easterly, downsloping winds, Plot valid 2/5 2343z

7. FORECAST PERIOD BEGINS!

8. Forecast Concerns- High Wind Potential Will 850 mb winds mix to the surface? 850 mb observations valid at 2/6 12z

9. Forecast Concerns- Freeze Possibility? Plot valid 2/6 1243z <= 32°F for 3 hours is need for Freeze/Frost to verify

10. Forecast Concerns- 2/6 12z Easterly winds at the onset?

11. HPC Analysis, Monday 2/6 12z

12. HPC Analysis, Tuesday 2/7 00z

13. HPC Analysis, Tuesday 2/7 12z

14. Regional Radar- 2/7 0201z

15. Regional Radar- 2/7 0800z

16. Regional Radar- 2/7 1159z

17. Eliminating Categories “All-zero categories” – All winter precipitation events (Categories 1-11) Used Redding observations and other cold sites to rule these out. Temperatures increased through our period. Also used NOHRSC database:

18. Eliminating Categories No snow=no blowing & drifting snow (Cat. 15) No blowing dust reports (Cat. 14) No smoke reported in ASOS/AWOS obs. (Cat. 16) – Note: We did read through every ASOS/AWOS ob. Visibilities from reports > 0.5 mile (No to Cat. 17) Wind chill and extreme chill ruled out from coldest sites and wind chill chart (Cat. 18 & Cat. 19) Flood categories (Cat. 21-24) ruled out via ASOS/AWOS obs and Mesonet obs found at http://www.wrh.noaa.gov/sgx/gmap/index.php http://www.wrh.noaa.gov/sgx/gmap/index.php

19. Eliminating Categories Lightning (Cat. 25) ruled out based on PSU eWall lightning data (next slide) Thunderstorm and severe thunderstorm (Cat. 26 & 27) ruled out based on ASOS/AWOS reports and lack of lightning

21. Verifying High Winds/Severe Winds Checked each ASOS/AWOS ob in our zones Example: KSNS 071153Z AUTO 11031G38KT 10SM FEW120 16/01 A2973 RMK AO2 PK WND 11038/1153 SLP077 60000 T01610006 10178 20150 58015 TSNO Also used max wind reports from NWS Mesonet – Checked data quality by using surrounding reports

22. High Wind Verification Zones 1-4, 505, 508, 510, 512, 513, 517, 518, 528

23. Severe Wind Verification Zones 1 and 510 Gusts exceeded 50 knots

24. Verifying Temperatures Again ASOS/AWOS, Mesonet reports were used. Every zone examined in this way

25. Freeze Verification Zones 4 & 15 Highest elevation sites P-type again was not an issue as warm air pushed temperatures above freezing

26. Temperature ≥ 68°F Verification

27. Zones 1, 3, 508, 510- 511, 513-518, and 528 Easterly winds the culprit!

28. Verifying Precip Used ASOS/AWOS and Mesonet reports Different format for Mesonet reports: http://www.cnrfc.noaa.gov/google_precip.php http://www.cnrfc.noaa.gov/google_precip.php Radar imagery (as seen before) Radar estimated rainfall: http://water.weather.gov/precip/ http://water.weather.gov/precip/

29. Mesonet Reports

30. Precipitation Ending 2/7 12z

31. ≥0.25” Precip Verification Zones 2, 17, 18, 63, 64, 76, 505-507, 510

32. 3 hours of Precip Verification Same zones verified as ≥0.25” precip category Zones 2, 17, 18, 63, 64, 76, 505-507, 510 Used radar, ASOS/AWOS, and mesonet reports

33. Verification Summary No zones verified for Cat. 1-11, 14-19, & 21-27 Zones that verified for high winds: 1-4, 505, 508, 510, 512, 513, 517, 518, 528 Zones that verified for severe winds: 1 & 510 Zones that verified for freeze/frost: 4 & 15 Zones that verified for T ≥ 68°F: 1, 3, 508, 510- 511, 513-518, and 528 Zones that verified for Precip. Total ≥0.25” and 3 hours of precip: 2, 17, 18, 63, 64, 76, 505-507, 510

34. Lessons Learned Beware of downsloping winds! Timing of precip- GFS more on target than NAM – Progression of storm system faster over water? Look at observations first while forecasting – Leads to “gimme” points Overlay terrain map on zone map, where is terrain an issue? For verifying out west: Mesonet data!