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USNA News Center

Winter arrives this weekend (14 DEC 2016)

  POSTED ON: Wednesday, December 14, 2016 9:55 AM by Meteorologist A.R. Davies

A complex weather pattern is on tap over the next few days.  First, a potent cold front will push through tonight.  Some light snow showers will be possible before dawn on Thursday.  Behind the front, expect blustery conditions as an arctic air mass settles in for the remainder of the work week. The wind chill temperatures will remain below 20 oF throughout the day on Thursday, and will drop into the single digits Thursday night and Friday morning.  The figure below shows modeled wind chill temperatures at 0700 EST on Friday.

16 Dec 2016 Wind Chill Tenps

Another cold front will pass the region during the day on Sunday.  However, out ahead of the cold front, a warm front will push through on Saturday with an associated precipitation shield set to arrive as early as Friday evening. Temperatures will likely remain below freezing at the surface through mid-morning on Saturday in Annapolis, however the temperatures in the atmosphere aloft will gradually warm prior to that time as the warm front approaches.  This will set-up a scenario where the column of air above us will support light snow or snow/sleet overnight on Friday (1.0 to 2.0 inches possible), before turning to a nasty mix of sleet, freezing rain, and rain around dawn on Saturday and lingering through mid-morning.  By late morning, the precipitation will likely be all rain in Annapolis.  Locations south of Annapolis will likely transition to rain sooner, while locations north of Annapolis will transition later. While there is model agreement that the surface temperatures will remain below freezing through mid-morning on Saturday, the models do not agree how quickly the column of air overhead will warm, and that ultimately determines how quickly the transition from snow to sleet to freezing rain will occur.  The rain will become light Saturday afternoon/evening and the temperatures will quickly warm to near 50 oF behind the warm front. The figure below shows how the latest American/GFS model projects the storm timeline and precipitation types. The full USNA forecast available at www.usna.edu/weather.

Ptypes on 17 Dec 2016

The cold front will finally pass around midday on Sunday with periods of rain Sunday morning and rain/snow behind the front Sunday afternoon/evening and overnight. It is unclear at this time how quickly the temperatures will drop behind the front or how long the precipitation will linger; those factors will determine if we transition back to light snow on Sunday evening.  Snow showers could linger into Monday as an area of low pressure moves along the departing cold front.  The figure below shows the possibility of light snow pre-dawn on Monday morning.  Check www.usna.edu/weather or www.facebook.com/usnaoceanography for updates.

Snow on Monday 19 Dec?

ISSUED: 14 December  2016 at 1000
FORECASTER: Meteorologist A.R. Davies
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Category: General Interest

Alexander R. Davies

Meteorologist & Oceanographer
Oceanography Department, U.S. Naval Academy
  adavies@usna.edu
  410-293-6565