Probabilistic Snowfall Forecast - National Weather Service

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Probabilistic Snowfall Forecasts
Probabilistic Ice Accumulation Forecasts
Winter Storm Outlook and Winter Storm Severity Index
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Medium/Long Range Forecast

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3 Day (72 Hour) Snow/Sleet Amount Potential Experimental - Leave feedback Click here for more information on these products Click here for more time windows at the NWS Probabilistic Precipitation Portal
Expected Snowfall - Official NWS Forecast The "Point" 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. Note that forecast snow amounts also includes sleet. The "Range" map is the 25th percentile (lower number) to 75th percentile (higher number) of possible snowfall amounts based on the Weather Prediction Center (WPC) Super Ensemble output during the time period of the graphic. The official NWS snowfall forecast influences this range of values either up or down depending upon how closely they match.	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. 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.

Percent Chance That Snow Amounts Will Be Greater Than... Experimental - Leave feedback Click here for more information on these products 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 - Leave feedback Click here for more information on these products 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

3 Day (72 Hour) Ice Accumulation Potential Experimental - Leave feedback Click here for more information on these products Click here for more time windows at the NWS Probabilistic Precipitation Portal
Expected Ice Accumulation - Official NWS Forecast The "Point" map is the official NWS ice accumulation forecast in inches during the time period shown on the graphic. This ice accumulation 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. The "Range" map is the 25th percentile (lower number) to 75th percentile (higher number) of possible ice accumulation amounts based on the Weather Prediction Center (WPC) Super Ensemble output during the time period of the graphic. The official NWS ice accumulation forecast influences this range of values either up or down depending upon how closely they match.	High End Amount 1 in 10 Chance (10%) of Higher Ice Accumulation What's this?
	Low End Amount 9 in 10 Chance (90%) of Higher Ice Accumulation What's this?
Low End Amount – 9 in 10 Chance (90%) of Higher Ice Accumulation This map depicts a reasonable lower-end ice accumulation amount for the time period shown on the graphic, based on many computer model simulations of possible ice accumulation 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. High End Amount – Only a 1 in 10 Chance (10%) of Higher Ice Accumulation This map depicts a reasonable upper-end ice accumulation amount for the time period shown on the graphic, based on many computer model simulations of possible ice accumulation 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.

This is the elevated flat surface ice accumulation. It is not radial/line ice. Radial/line ice is typically 39% of the elevated flat surface ice. For more information on this, see this module. Back to top

Percent Chance That Ice Accumulation Will Be Greater Than... Experimental - Leave feedback Click here for more information on these products What's this?

Percent Chance That Ice Accumulation Will Be Greater Than

This series of maps shows the probability (that is, the likelihood) that ice accumulation 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.

>=0.01"	>=0.1"	>=0.25"	>=0.5"	>=0.75"	>=1"	>=1.25"	>=1.5"

Ice Accumulation by Location Experimental - Leave feedback Click here for more information on these products What's this?

Ice Accumulation Totals by Location

These tables show the ice accumulation 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

Winter Storm Severity Index (WSSI)	Winter Storm Outlook (WSO)

Local Snow Reports	National Snowfall Analysis
National Snowfall Reports/Analysis

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Days 4-7 Winter Weather Outlook
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