National Weather Service United States Department of Commerce

Snow in the Great Lakes; Windy Conditions in the East

Lake effect snow will impact the Great Lakes region through the day. Gusty winds will pick up across the Midwest, Northeast and Mid-Atlantic beginning this afternoon following a cold front. Elevated fire weather conditions will persist across the Desert Southwest today, with critical fire weather conditions developing Wednesday and Thursday in the Southern Plains. Read More >

San Francisco Bay Area, CA

Weather Forecast Office

Probabilistic Snowfall Forecasts

Weather.gov > San Francisco Bay Area, CA > Probabilistic Snowfall Forecasts
Snow Amount Potential
Experimental -
Expected Snowfall - Official NWS Forecast

What's this? 		High End Amount
1 in 10 Chance (10%) of Higher Snowfall

What's this?
Low End Amount
9 in 10 Chance (90%) of Higher Snowfall

What's this?

Low End Amount – 9 in 10 Chance (90%) of Higher Snowfall

 

This map depicts a reasonable lower-end snowfall amount for the time period shown on the graphic, based on many computer model simulations of possible snowfall totals. This lower amount is an unlikely scenario with a 9 in 10, or 90% chance that more snow will fall, and only a 1 in 10, or 10% chance that less snow will fall. This number can help serve as a lower-end scenario for planning purposes.

Expected Snowfall - Official NWS Forecast

 

This map is the official NWS snowfall forecast in inches during the time period shown on the graphic. This snowfall amount is determined by NWS forecasters to be the most likely outcome based on evaluation of data from computer models, satellite, radar, and other observations.

High End Amount – Only a 1 in 10 Chance (10%) of Higher Snowfall

 

This map depicts a reasonable upper-end snowfall amount for the time period shown on the graphic, based on many computer model simulations of possible snowfall totals. This higher amount is an unlikely scenario, with only a 1 in 10, or 10% chance that more snow will fall, and a 9 in 10, or 90% chance that less snow will fall. This number can help serve as an upper-end scenario for planning purposes.
 
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.
Percent Chance That Snow Amounts Will Be Greater Than...
Experimental -
What's this?

Percent Chance That Snow Amounts Will Be Greater Than

 

This series of maps shows the probability (that is, the likelihood) that snowfall will equal or exceed specific amounts during the time period shown on the graphic. These forecasts are based on many computer model simulations of possible snowfall totals.
Hover over thumbnails below to view larger image.
>=0.1"
>=1"
>=2"
>=4"
>=6"
>=8"
>=12"
>=18"

Snowfall Totals by Location
Experimental -
What's this?

Snowfall Totals by Location

 

These tables show the snowfall forecast for individual locations, and provide the same information as the graphics on this web page, just shown in a different way. All of these values are valid for the same time period as depicted on the graphics.

Location Low-End
Amount		 Expected
Amount		 High-End
Amount		 Chance of Seeing More Than
 
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