Winter Weather

   Winter Weather   

Local Products

• Storm Total Snow and/or Ice Accumulation Forecasts
  - Official snow and ice forecasts out to three days from NWS Mt. Holly. Includes our experimental probabilistic snowfall forecast maps.
• Criteria for Winter Storm Watch/Warning/Advisory Products Changing in Western Chester County this Season
• Public Information Statement (PNS)
  - discusses snowfall totals during or immediately after a winter weather event
• ER Weather Event Display
  - Map of snow and ice reports during and immediately after a winter weather event
• Storm Archives
  - snowfall plots and storm summaries for major events
• Hazardous Weather Outlook
• Ice Buildup on Local Rivers
• Snow Cover and Depth

Winter Products from National Centers

• Climate Prediction Center (CPC)
• Weather Prediction Center (WPC) Winter Weather Forecasts
• National Operational Hydrologic Remote Sensing Center (NOHRSC) Snow Analysis (interactive map)
• National Ice Center

El Niño and La Niña Effects on Philadelphia Winters (since 1950)

Watch/Warning/Advisory Terminology & Criteria

• Warnings:
  A warning is issued to alert the public to imminent dangerous winter weather. Normally a warning is issued after a winter storm watch has been in effect. A winter storm watch may not precede a warning if winter weather develops quickly and unexpectedly. A Winter Storm Warning is issued when heavy snow, significant freezing rain, or heavy sleet is expected to occur. Usually issued 6 to 18 hours in advance of the winter weather. A Blizzard Warning is issued when sustained or gusty winds of 35 mph or more are expected to reduce visibility at or below a quarter of a mile due to falling and/or blowing snow for at least three hours. Wind Chill Warnings are issued when wind chills are expected to be below -24 degrees fahrenheit.
• Watches:
  A watch is issued to alert the public to the potential for dangerous winter weather. A Winter Storm Watch is issued when conditions exist for the possible occurrence of dangerous winter weather such as a blizzard, heavy snow, significant freezing rain or heavy sleet. Usually issued 12 to 36 hours in advance of the winter weather.
• Advisories:
  A less severe winter weather event will prompt the issuance of an advisory. An advisory is named specific to the weather event expected and is issued when the event is expected to be widespread. Travel by foot or vehicle may be dangerous during an advisory even if the winter weather is not expected to reach winter storm criteria.

Snowfall from Past Winters

Seasonal Snowfall Totals from 1979-Present (updated March 2016):

• Philadelphia, PA
• Allentown, PA
• Atlantic City, NJ
• Wilmington, DE

Preliminary Top Ten Philadelphia Snow Storms (updated Feb 2016):

Winter Weather Awareness and Safety

• NWS Winter Weather Safety
• NWS Winter Weather Awareness
• Wind Chill Information and Chart