Wednesday, March 07, 2018

Probabilistic QPF In New England

Someone asked recently about ensembles and probabilistic forecasting. The Northeast NWS Forecast Offices have been issuing experimental QPF snow forecasts this winter, as per:

The purpose of these experimental probabilistic snowfall products is to provide customers and partners a range of snowfall possibilities, in complement to existing NWS deterministic snowfall graphics, to better communicate forecast uncertainties during winter weather events. For more information visit this project's Product/Service Description Document, and please provide us your feedback here.

Top is webcam view this am from Albany, New York, as another storm strikes at New England. Note that the streets are just wet at this time - whether the roads will have snow or ice cover is a very important, but somewhat different aspect of winter forecasting. Below is the current NWS Albany Office deterministic forecast of storm-total snowfall.

Here are the current probabilistic forecasts for low end snowfall (below) and top end amounts below - both forecasts being at the 10% chance level. These were developed using various ensemble forecasts and illustrate - to some degree - where probabilistic forecasting is finally headed. Kudos to NWS Eastern Region (others also?).

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