GEOS-FP Excels At Predicting Presidents' Week Mid-Atlantic Snowfall

Authors: Bill Putman, Bennett Erdman

The active 2024-2025 winter season in the Mid-Atlantic continued over President’s Day week, with the region experiencing substantial snowfall. Most long-range numerical weather prediction (NWP) models initially placed the highest snowfall totals falling along the I-95 corridor in MD, PA, and VA, then gradually shifted this bullseye south in the days leading up to the event. One model in particular stood out from the rest, though, and had both the location and magnitude of the storm correct from the start: the GMAO’s GEOS-FP.

slide graphic from TC Akara
Figure 1: GEOS-FP held the location of the heaviest snow amounts to coastal Virginia and North Carolina as far as 120 hours from the actual snowfall (top left). Despite a bit of fluctuation in totals 3 days out (top right), GEOS-FP held its high-end totals of 8-10 inches of snow for the better part of a week leading up to the storm. This proved to be the correct solution, with GEOS-FP's 24 hour forecast (bottom left) closely matching observed totals (bottom right).

As far as 192 hours before the storm (not pictured), GEOS-FP indicated the heaviest snowfall would occur in the Tidewater region, then held this solution until the start of the event. While other operational models ended up agreeing with this solution, the majority did not shift to this forecast until roughly 72 hours before the storm. Additionally, while some models showed totals of 18+ inches, GEOS-FP generally maintained an upper range of roughly 8-12 inches, with the exception of a couple initializations.

References:

Snowfall Observations: https://www.nohrsc.noaa.gov/nsa/

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