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Verification of the RWFS (Road Weather Forecast System)

Verification of the RWFS (Road Weather Forecast System). Ben C. Bernstein Jamie Wolff, Seth Linden NCAR/RAP Boulder, CO. Purpose and Presentations. Take a close look at key aspects Quality, performance… Case studies What did the forecasts look like before events Heavy event: 2/15/03

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Verification of the RWFS (Road Weather Forecast System)

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  1. Verification of the RWFS(Road Weather Forecast System) Ben C. Bernstein Jamie Wolff, Seth Linden NCAR/RAP Boulder, CO

  2. Purpose and Presentations • Take a close look at key aspects • Quality, performance… • Case studies • What did the forecasts look like before events • Heavy event: 2/15/03 • Light event: 2/4/03 • How did the case evolve • Key factors • Recommended vs actual treatments (two I-35 segments) • Bulk statistics • Individual sites and all Iowa sites combined • Weather parameters • Road temperature • Thanks to IA DOT & CTRE – data collection

  3. Road Segments

  4. A heavy snow event:Feb 14-16, 2003

  5. 2/14/03 – 6Z (midnight)A classic storm was setting up… +

  6. NWS Forecasts, 4am (9Z) Feb 14 IAZ047>050-061-062-142157- BOONE-JASPER-MARSHALL-POWESHIEK-STORY-TAMA- INCLUDING THE CITIES OF...AMES...BOONE...GRINNELL...MARSHALLTOWN... NEWTON 357 AM CST FRI FEB 14 2003 ...WINTER STORM WARNING FOR TODAY AND TONIGHT... .TODAY...WIDESPREAD FREEZING RAIN...SNOW...OR SLEET. ACCUMULATION 2 TO 3 INCHES. TEMPERATURES STEADY IN THE UPPER 20S. EAST WINDS 10 TO 20 MPH. CHANCE OF PRECIPITATION 90 PERCENT. .TONIGHT...WIDESPREAD SNOW. TOTAL ACCUMULATION 4 TO 6 INCHES. BRISK WITH BLOWING AND DRIFTING SNOW. LOW IN THE MID TEENS. NORTHEAST WINDS 15 TO 25 MPH...GUSTING TO 30 MPH. CHANCE OF SNOW 80 PERCENT. .SATURDAY...CLOUDY WITH A CHANCE OF SNOW. HIGH IN THE LOWER 20S. NORTHEAST WINDS 10 TO 20 MPH. CHANCE OF SNOW 50 PERCENT. .SATURDAY NIGHT...PARTLY CLOUDY. LOW NEAR 10. IAZ044-057>060-142157- AUDUBON-CRAWFORD-DALLAS-GUTHRIE-POLK- INCLUDING THE CITIES OF...DENISON...DES MOINES 357 AM CST FRI FEB 14 2003 ...WINTER STORM WARNING FOR TODAY AND TONIGHT... .TODAY...WIDESPREAD FREEZING RAIN...RAIN...OR SLEET. ACCUMULATION 1 TO 2 INCHES. HIGH IN THE LOWER 30S. EAST WINDS 10 TO 20 MPH. CHANCE OF PRECIPITATION 90 PERCENT. .TONIGHT...WIDESPREAD SNOW. TOTAL ACCUMULATION...4 TO 7 INCHES. BRISK WITH BLOWING AND DRIFTING SNOW. LOW IN THE MID TEENS. NORTHEAST WINDS 15 TO 25 MPH...GUSTING TO 30 MPH. CHANCE OF SNOW 80 PERCENT. .SATURDAY...CLOUDY WITH A CHANCE OF SNOW. HIGH IN THE LOWER 20S. NORTHEAST WINDS 10 TO 20 MPH. CHANCE OF SNOW 50 PERCENT. .SATURDAY NIGHT...PARTLY CLOUDY. LOW NEAR 10 ABOVE.

  7. RWFS Forecast3Z – 14 Feb 2003 RUN

  8. RWFS – predicted storm totals Snowfall (inches) QPF (inches) Storm totals – much of QPF expected to fall as freezing rain

  9. Forecast at Ames (reprocessed)

  10. Forecast at Des Moines (rep.)

  11. The event – 2/14/03, 6am-12pm + AMW: -1oC, BKN DSM: 0oC, OVC + AMW: 0oC, OVC DSM: 2oC, -RA

  12. 2/14/03, 11a.m. (17Z)Changes: NWS & RWFS DES MOINES IA-HENDERSON IL-HENRY IA-JEFFERSON IA-KEOKUK IA-LOUISA IA- MERCER IL-WARREN IL-WASHINGTON IA- INCLUDING THE CITIES OF...ALEDO...BURLINGTON...FAIRFIELD...MONMOUTH... MOUNT PLEASANT...OQUAWKA...SIGOURNEY...WAPELLO...WASHINGTON 1137 AM CST FRI FEB 14 2003 UPDATED TO ADJUST TIMING OF WATCH AND MAKE TWEAKS TO PCPN/TEMPS ...WINTER STORM WARNING LATE THIS AFTERNOON THROUGH SATURDAY... .THIS AFTERNOON...OCCASIONAL LIGHT RAIN OR DRIZZLE...POSSIBLY MIXED WITH SLEET. PRECIPITATION CHANGING TO ALL SNOW LATE. HIGH IN THE UPPER 30S. EAST WIND 10 TO 20 MPH. CHANCE OF PRECIPITATION 80 PERCENT. .TONIGHT...SNOW AND BLOWING SNOW. ACCUMULATIONS 3 TO 5 INCHES. WINDY WITH A NORTHEAST WIND 20 TO 30 MPH. LOW IN THE LOWER 20S. CHANCE OF SNOW 90 PERCENT. .SATURDAY...SNOW TAPERING TO FLURRIES. CONTINUED WINDY WITH BLOWING SNOW. TOTAL ACCUMULATIONS...5 TO 9 INCHES. TEMPERATURES STEADY IN THE MID 20S. NORTHEAST WIND 20 TO 30 MPH...DIMINISHING TO 15 TO 25 MPH. CHANCE OF SNOW 80 PERCENT. BOONE-MARSHALL-STORY-TAMA- INCLUDING THE CITIES OF...AMES...BOONE...MARSHALLTOWN 350 PM CST FRI FEB 14 2003 ...WINTER STORM WARNING FOR TONIGHT... .TONIGHT...FREEZING RAIN...RAIN...OR SLEET THIS EVENING…THEN CHANGING TO ALL SNOW...HEAVY AT TIMES. TOTAL ACCUMULATION...4 TO 8 INCHES. WINDY WITH BLOWING AND DRIFTING SNOW. LOW IN THE MID TEENS. NORTHEAST WINDS 15 TO 30 MPH...GUSTING TO 40 MPH. .SATURDAY...CLOUDY WITH A CHANCE OF SNOW. BRISK. HIGH IN THE LOWER 20S. NORTHEAST WINDS 15 TO 25 MPH...GUSTING TO 30 MPH. CHANCE OF SNOW 50 PERCENT.

  13. The event – 2/14/03, 6pm-12am + AMW: 0oC, OVC DSM: 1oC, -RA + AMW: -3oC, -SN DSM: -2oC, +SN

  14. The event – 2/15/03, 6am-12pm + AMW: -6oC, -SN DSM: -6oC, +SN + AMW: -7oC, -SN DSM: -7oC, -SN

  15. The event – 2/16/03, 6pm + AMW: -7oC, BKN, SNE1803 DSM: -7oC, OVC, SNE2030

  16. A closer look – important features

  17. Forecast vs. Observed 2/14/03 – 3Z RUN QPF SNOW 10.9

  18. Temperature forecast: Ames 6am mid 6pm noon 6pm noon

  19. Treatment comparison: Ames mid 6pm 6pm noon noon 6am 6am

  20. Temperature forecast: Des Moines 6am mid 6pm noon 6pm noon

  21. Treatment comparison: Des Moines mid 6pm 6pm noon noon 6am 6am

  22. Heavy Event Summary • RWFS forecast • Temperature: CRITICAL • Precipitation: location, timing, amount • PRECIPITATION TYPE • Improved later on 2/14, ditto for others • Treatment • Reasonable given forecast • Matched reality? • Lessons • Value of COND probability info for precipitation type • Forward error correction (TEMP)

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