18th Conference on Weather and Forecasting, 14th Conference on Numerical Weather Prediction, and Ninth Conference on Mesoscale Processes

Tuesday, 31 July 2001: 1:20 PM
AFWA MM5 Performance During the "Millenium Storm" and the Winter 2000–2001 Storm Season
Gordon R. Brooks, Air Force Weather Agency, Offutt AFB, NE; and R. J. Swanson Jr., R. J. Craig, R. B. Telfeyan, J. J. Wesely, C. Stock, and R. Nielsen
Poster PDF (87.1 kB)
Strong cyclogenesis occurred along the east coast of the United States on December 31st, 2000. Because of the timing of this storm, at the end of the millenium, it was coined the "Millenium Storm." This paper describes the performance of the Air Force Weather Agency's (AFWA's) operational model -- the Penn State University (PSU)/National Centers for Atmospheric Research (NCAR) Mesoscale Model 5 (MM5) during this event.

The AFWA/MM5 performed remarkably well; providing 72-hour notification on the strength of the cyclone, it's track along the east coast, and the variation of precipitation types and precipitation totals across the northeastern states. The model has also performed well forecasting other notable storms during the 2000-2001 winter season. In addition to the "Millenium Storm," the February 4-6, 2001 Nor’easter, several Midwest storms, and the December 2000 Southern Plains ice storms will also be discussed.

This study begins with an overview of the operational configuration of the AFWA/MM5; including initialization scheme, model dynamics and physical parameterizations. Because the study keys on the millenium storm and one other significant Nor'easter, special emphasis will be placed on the ocean data (SSTs) used in the operational forecast.

The study also contains point verifications for several key locations along the east coast of the United States. AFWA/MM5's performance during the "Millenium Storm" was particularly noteworthy across the Washington D.C. area where the media (based on operational model guidance) forecast significant snowfall. AFWA/MM5 correctly indicated that cyclogenesis would occur just off the southern coast of New Jersey, not Cape Hatteras as other models suggested. This difference, in location of initiation of cyclogenesis, contributed to the correct forecast by the AFWA/MM5 of only flurries for the Washington D.C. and Virginia area on the backside of the storm system as it developed and moved northeastward. The AFWA/MM5's performance during the February 4-6 Nor'easter, was in some respects more impressive. The model not only correctly forecasted precipitation totals, it also handled the variation in preciptation types (both in timing and location) with remarkable accuracy.

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