EMC's Model Evaluation Group

 The Model Evaluation Group (MEG) community is established to interact with the user community on issues related to the forecast systems of NCEP's Environmental Modeling Center (EMC).    It is used to discuss overall model performance and provide feedback on operational and parallel versions of the models which comprise the production suite.

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FV3 "snowy" forecast for Mid-Atlantic Dec 8-9, 2017

FV3 "snowy" forecast for Mid-Atlantic Dec 8-9, 2017
model comparison
Answer
12/6/17 9:05 PM

A comparison of GFS vs FV3 fields of  "24-hr snowfall" has shown some wide differences across the Mid-Atlantic region for the valid 24hr time period  06Z-06Z Dec 8-9, 2017. The position and strength of a Low moving up the southeast coast during the forecast period appears to account for much of the differences.  Images are attached that include various forecasts made 04 and 05 Dec 2017.

Unfortunately, due to system maintenance, FV3 runs will be missing for most of 05 and 06  Dec, so continuity monitoring is impossible.

The main differences are 1) FV3 maintains sfc low closer to the coast thus keeping snow swath further inland and 2) FV3 has (imho) aggressively high snow totals compared to the GFS for a few of the forecasts during this time period (particularly the 18Z run on 05 Dec 2017 that has a swath of 6-12" snow along much of the eastern seaboard).

As I write this (19Z-06 Dec 2017), I know not to criticize a forecast until after its forecast valid time has been met. But first looks suggest the FV3 is maybe too far inland and has too much "snowfall" (also realizing that model-computed snowfall forecasts leave much to be desired).

(Note...I couldn't upload the images...take at lookat the 18Z comparison for 05 Dec 2017 for snowfall)

Steve Zubrick/SOO-WFO Sterling-19Z/06 Dec 2017