Warmth and Showers Leading Up to Christmas

    Winter officially begins on December 21st, but it will feel a lot more like October over the next several days, as temperatures increase throughout the week, culminating in what will likely be record-shattering warmth on Christmas Eve.  Through December 19th, Philadelphia is 11.2° above average for the month, and above average temperatures will generally be the main story through the end of the year.  The period of December 10-18th saw temperatures of 11-24° above average itself, and no day this month has been below average thus far.  Below is my forecast for our holiday week, with still some uncertainty for rainfall totals on Wednesday and temperatures for Christmas Day.

Monday

  As a weak cold front approaches from the west, it will dissipate and 'likely' leave us dry.  We'll see a gradual increase in clouds through the day, with partly/mostly cloudy conditions in general.  Our week of mild temperatures will begin with a high of 55-60°.

Tuesday

  An upper-level disturbance moves through the Northeast and brings clouds and the threat of showers for the morning/afternoon, with any precipitation likely ending by sunset.  We'll likely see upward of a tenth of an inch or so, with a high of around 60°.

Wednesday

  A frontal boundary approaches from the west, a warm front will move through the area, and precipitation will overtake the area.  Periods of showers and rain will fall throughout the day as a low pressure system strengthens over the Great Lakes, providing for windy conditions as well as rain.  It appears at this time, with upward of 0.50-1.00" possible and a high in the mid-60's (Philadelphia's record high is 66°).  Below is modeled radar for 4pm on Wednesday:

Modeled radar from the NAM for 4pm on 12/23 (Image courtesy of TropicalTidbits.com)

Christmas Eve

  Any lingering showers end by the afternoon, and high pressure from the west should begin to dry things out with some clearing.  We'll likely remain breezy, as temperatures soar to 70°+ (current trends are for the low- to mid-70's!).  The record high for Philadelphia is 64°, and it's looking like this record will be shattered.  Below is the GFS MOS Data that shows modeled record temperatures for Thursday:

Christmas Day

  High pressure will continue to build in to provide for a dry and mild holiday, with temperatures still uncertain but likely nearing 60°, but it really depends on the timing of our frontal passage.