National Weather Service United States Department of Commerce

         

         

When winter weather threatens, your National Weather Service in Jackson issues watch, warning, and advisory products to warn you of the impending hazard.  Winter weather is often the most difficult weather for the ArkLaMiss, both because it causes travel problems, and because it is difficult to forecast.


Winter Weather Definitions
NWS Jackson will issue winter weather products based on the following definitions:
  • Blizzard: defined as having sustained winds of 35 mph, or frequent gusts to 35 mph or higher as well as considerable falling and/or blowing snow that frequently reduces the visibility to less than 1/4 mile. These conditions are expected to prevail or last for 3 hours or longer.
  • Heavy snow: snowfall accumulations of 2 inches or more in 12 hours or less.
  • Ice/Sleet storm: When freezing rain is expected to accumulate 1/4 inch or greater during a 12-24 hour period. For sleet, the accumulation of 0.5 inches is used.
  • Freezing Rain(or Drizzle): Rain that freezes on objects as it strikes them.
  • Sleet: Solid granules of ice which form from the freezing of super-cooled raindrops or refreezing of largely melted snowflakes.
  • Wind Chill: when wind chill temperatures are expected to fall below 10 degrees. This generally occurs when temperatures are 10 to 15 degrees and wind speeds of 10 to 15 mph.
Latest Winter Weather Product
Winter Storm Watch (WSW)   
A Winter Storm Watch will be issued when conditions are favorable for hazardous winter weather conditions to develop.  Unlike a Tornado Watch or a Severe Thunderstorm Watch, Winter Storm Watches are issued by the local office.  Generally, this type of watch is issued for weather conditions that could occur 24 to 48 hours in the future.  Information in the watch will include the affected area, the weather threat involved, potential precipitation amounts, explanation of what a watch is, the uncertainty involved, precautions recommended, and the storm's potential impact. NWS Jackson issues a Winter Storm Watch when one or more of the following is possible (50% or greater confidence) during the next 12 to 36 hours:

· Snowfall of 2+ inches in 12 hours
· Accumulation of freezing rain (ice) greater than 0.25".
· Greater than 0.50" of sleet accumulation expected.
Winter Storm Warning (WSW)  
A Winter Storm Warning is issued when a combination of hazardous winter weather is occurring, is imminent, or is expected.  Winter Storm Warnings are issued when one or more of the following is expected:

· Snowfall of 2+ inches in 12 hours
· Accumulation of freezing rain (ice) greater than 0.25".
·  Greater than 0.50" of sleet accumulation expected.
Blizzard Warning (WSW)  
A Blizzard Warning will be issued when winds of 35 mph (sustained or frequent gusts) or stronger combine with considerable falling, blowing, and/or drifting snow, for 3 hours or more with visibilities of 1/4 mile or less.  This condition will be extremely infrequent in the ArkLaMiss region.
Ice Storm Warning (WSW)  
An Ice Storm Warning is issued when greater than 0.25" freezing rain(ice) or 0.50" of sleet is forecast to accumulate.  Heavy accumulations of ice produce extremely dangerous and damaging situations, primarily by pulling down trees and utility lines.
Winter Weather Advisory (WSW)  
A Winter Weather Advisory is issued for a winter weather situation that causes significant inconveniences, but does not meet warning (see above) criteria.  The winter weather can still be life threatening if caution is not exercised, and frequently a winter weather advisory will be issued if travel impacts can be expected.   A Winter Weather Advisory is issued if one or more types of hazardous winter weather is expected, is occurring, or is imminent:

· Sleet and/or snowfall of 1-2 inches in 12 hours.
· Accumulation of freezing rain (ice) less than 0.25".


Wind Chill Advisory (WSW)  
A Wind Chill Advisory is issued when cold temperatures and breezy winds combine to create a wind chill 9 degrees and -14 degrees for an hour or more.
Wind Chill Warning (WSW)  
A Wind Chill Warning is issued when cold temperatures and breezy winds combine to create a wind chill below -15 degrees for an hour or more.  
 
 
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