National Weather Service United States Department of Commerce
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.


 

Snow Accumulation Potential
Experimental -
 
EXPECT AT LEAST THIS MUCH MOST LIKELY SNOWFALL POTENTIAL FOR THIS MUCH
   
Minimum Potential Snow Accumulation
Most Likely Snow Accumulation (Point)Most Likely Snow Accumulation (Range)
Maximum Potential Snow Accumulation
What's this? What's this? What's this?

Minimum Potential Accumulation

Expect at least this much. This is what we see as the least amount of snow the storm can produce.

This information is for advance planning ahead of the storm. It is provided out as far as three days. However, when the snow starts to fall, this will be discontinued to focus on the forecast snow amount.
 

Most Likely Snow Accumulation

Represents our official snow forecast in inches within the next one to three days. The snowfall amounts are provided in point (single number) and ranges (1-2", 2-4", etc.). You can toggle between the two by hovering over the "Point" and "Range" text above the image. The point amount is our forecast but the range for the "most likely" represents the forecast uncertainty in predefined ranges.

Maximum Potential Accumulation

What you should be prepared for. This is what we see as the storm's maximum potential snowfall accumulation.

This information is for advance planning ahead of the storm. It is provided out as far as three days. However, when the snow starts to fall, this will be discontinued to focus on the forecast snow amount.

 

Ice Accumulation Potential
 
  MOST LIKELY ICE GLAZE  
  Most Likely Ice Accumulation

What's this?
Impacts Amount Forecast
Icy Spots Expected
Beware driving or walking. Some areas will be icy, some not.
Up to a Tenth
Widespread Icing
Limit unnecessary travel. Any untreated surface will likely be glazed with ice. Scattered power outages possible.
Tenth to a Quarter Inch
Ice Storm Expected
Numerous power outages. Downed branches. Extremely dangerous to walk or drive on untreated surfaces that will be ice covered.
Quarter Inch to a Half Inch
Severe Ice Storm
Widespread power outages, possibly for an extended time. Downed trees, and impassable roads expected.
Half Inch to an Three-Quarter Inch
Severe Ice Storm
Widespread power outages, possibly for an extended time. Many downed trees, and impassable roads expected.
Three-Quarter Inch up to an Inch
Devastating Ice Storm
Long term power outages. Many downed trees over roads and power lines. Impassable roads from icing and downed trees. Recovery could take many days.
Inch up to 2 Inches
Devastating Ice Storm
Long term power outages. Many downed trees over roads and power lines. Impassable roads from icing and downed trees. Recovery could take many days.
2 Inches or More

Most Likely Ice Accumulation

Represents our official ice forecast in inches within the next one to three days. The ice accumulation amounts are provided in ranges.

 

Percent Chance That Snow Accumulation Will Be Greater Than...
Experimental -
 
What's this?

Exceedance Probabilities

Represents the likelihood of exceeding a specific snowfall amount. Thresholds are 0.1", 1", 2", 4", 6", 8", 12", and 18". This product is designed to indicate high or low confidence in the official snowfall forecast.

Example: An 80% chance of exceeding 2" means that we have a high confidence that it will snow at least 2". Conversely, a 10% chance of exceeding 18" means that we have high confidence that it will snow less than 18".

Hover over thumbnails below to view larger image.
>=0.1"
>=0.1"
>=1"
>=1"
>=2"
>=2"
>=4"
>=4"
>=6"
>=6"
>=8"
>=8"
>=12"
>=12"
>=18"
>=18"

 

Chance of Snow Accumulation
Experimental -
 
What's this?

Snow Accumulation

Ranges

Represents the likelihood of various snowfall ranges. Amounts ranges are 0", 1-2", 2-4", 4-6", 6-8", 8-12", 12-18" and 18" +. This product is designed to indicate high or low confidence in the official snowfall forecast.

Exceedance

Represents the likelihood of exceeding a specific snowfall amount. Thresholds are 0.1", 1", 2", 4", 6", 8", 12", and 18". This product is designed to indicate high or low confidence in the official snowfall forecast.

County:
 

 

Other Snow/Ice Information
Storm Track Onset of Wintry Precipitation Reported Snow/Ice Totals
Storm Total Ice Graphic
Winter Precipitation Onset
What's this? What's this? What's this?

Low Tracks Graphic

The graphic depicts the forecast location of significant surface lows impacting the 48 contiguous United States in 12 hour increments out to 72 hours into the future.

The low position and track forecast by NCEP WPC meteorologist is in white. Each low position is accompanied by a lead time (Eastern Time). The circles around each low represents a 75% probability the observed low will be located with the circle. Note: The probability is derived using previous season's verification data. For reference, existing surface lows are depicted with a red marker without yellow circles.

Precipitation Onset

Most likely time of winter precipitation onset (snow, sleet, freezing rain). Rain is not included here. This information is provided when we issue a Warning or Advisory for expected snow or ice accumulation; typically six to 24 hours in advance. Times are only given for places that are under a Warning or Advisory. They will be blank in areas outside Warnings or Advisories.

Reported

As snow and/or ice reports come into the NWS (you can email reports to lwx-report@noaa.gov or Tweet to @NWS_BaltWash), we will pass them on here. With the map linked here, and the supporting reports below it, you can keep tabs on how much has fallen.

 

Winter Storm Threat: 3-7 Days From Now
Experimental -
What's this?
Product Description Document

 

Click on maps to see daily Confidence vs. Potential Impact graphic. (Click here to hide.)

 

 

Day 3 Day 4 Day 5 Day 6 Day 7
 
 
 
 
 

 

 

 

High High threat of high impact winter storm. Potential impacts include significant travel delays, closures, and threats to life and property.  Plan ahead to minimize impact on you and your family.
Moderate Moderate winter storm threat. Potential impacts include significant travel delays and closures. Plan ahead to minimize impact on you and your family.
Enhanced Enhanced winter storm threat. Primary threat is disruption to travel.
Slight Slight winter storm threat. If threat materializes, may cause travel disruptions.
None No significant winter storm threat is currently expected. However, light wintry precipitation may still be possible.

 

Long-Range Forecast
 
Days 4-5 Forecast Precipitation Days 6-7 Forecast Precipitation
Days 4-5 Precip Days 6-7 Precip
   

Days 6-10

Temperature  Precipitation
6-10 day temperature 6-10 day precipitation
   

Days 8-14

TEMPERATURE  PRECIPITATION
8-14 day temperature 8-14 day precipitation
   

Week 3-4

TEMPERATURE

PRECIPITATION

Week 3-4 Temperature Week 3-4 precipitation

 

Useful Winter Weather Information
Historic Mid-Atlantic
Winter Storms
Winter/Snowfall
Statistics
El Niño and
DC/Baltimore Winters
Watches, Warnings,
& Advisories
How to
Measure Snow
La Niña and
DC/Baltimore Winters
** BE PREPARED! **
At Home On the Road Outside in the Cold