MLK day Afternoon Disco

Synopsis

The mnst bitter cold of the season is on its way. The artic flow will be most intense tomorrow with subzero wind chills, yet the rest of the week will just remain frigid while a grey sky looms overhead for the bulk of the week, leading to a dreary few days of arctic-esque cold. A Nor'easter will pose a threat later in the week, so this should be on watch as the week progresses.

Short Term (Now through Wednesday night)

As the arctic front moves through the Northeast, light snow showers will begin to dissipate throughout the state overnight, leaving Erie with its own confined Lake effect setup.  The front will surpass the far eastern boundaries overnight, taking with it an intensifying pressure gradient that will help kick off 20mph winds for Tuesday. these surface winds will bring forth the subzero/nearzero wind chills for tomorrow afternoon.  at this time, in the upper levels. The flow will be depositing air out of the Yukon, and the 500mb longwave trough will help keep the cold air in plavce for the next week as it continues to dip further south. High pressure will start to build in overnight Tuesday, helping to calm, the winds, but keeping lows within the single digits statewide.  The dipping trough will progressively push this high pressure into the Southeast U.S., leaving us with a mean westerly influence for the day.

During this time, the WNW winds out over Lake Erie will intensify their ;ake effect snowbands, yet the models downplay the extent of the areal coverage. The SREFs indicate about 6 to 9 inches of new snowcover between now and Wednesday night, and the lake effect snow will not die out until Thursday afternoon. The NAM and other hi-res models keep the most intense snowfall confined to Erie and areas about 20 to 40 miles from the lakeshore.

Long Term (Thursday and Friday)

Here's where things get tricky, starting around 0z Thursday, the 12z NAM and GFS solutions begin to differ immensely.  By 18z Thursday, they both agree on a rather clear and Sunny Thursday, but around 0 to 6z Thursday, the solutions feature thick clouds blanketing the state with the GFS, and patchy clouds with the NAM. The NAM is colder during these days as well, by about 4 degrees on the low and high for both days. On Friday, the zoomed out GFS implies a strong Nor'easter over PA at 12z, but at 0z the GFS shopws no signs of the system, with it still developing in the Central U.S. at this time. Conversely, the Nam shows a semi-organized, intensifying cyclone around Chicago. His implies that the NAM will be faster than the GFS on this system, but it should be monitored more closely s the week progresses.

As far as Erie's concerned, between now and 0z Friday, the SREF ensemble mean gives them a foot of snow, with the members ranging from about 10 to 16 inches by that time.

Submitted by Steve Engblom Dos