1:10 PM | *60+ degrees tomorrow…much colder this weekend with some snow and/or ice possible on Sat./Sat. night…much warmer again later next week*

12Z GFS surface forecast map for early Saturday (snow in blue, ice in pink/purple); map courtesy tropicaltidbits.com, NOAA/EMC

Our topsy-turvy temperature pattern will continue over the next several days here in the Mid-Atlantic region.  Temperatures on Thursday will climb to the highest levels of the week with 60+ degrees likely for highs in the I-95 corridor from DC-to-Philly-to-NYC, but then a cold front slides through on Friday, Arctic high pressure builds to our north, and the weekend will turn out much colder. This same front will stall out nearby this weekend allowing for a couple of disturbances to ride along its boundary zone bringing us the chance for some snow and/or ice – depending on location.  At this time, this early weekend event appears to be on the light-to-moderate side in terms of total precipitation amounts.  Once the Arctic high pressure system pushes to the east early next week, much warmer weather will return to the Mid-Atlantic region and it could turn out to be the much coveted “January thaw” that we hope for every winter lasting several days.  A colder pattern is likely to return later this month.

There will be a decent rain event tonight as another warm front presses into the region from our south.  Following the passage of this warm front, much warmer air will ride in tomorrow on hefty S-SW winds and temperatures will climb to 60 degrees or above for highs in DC, Philly and NYC.  A cold front will then slide through early Friday – supported by expanding Arctic high pressure to our north – and the result will be a drop in temperatures Friday afternoon after a relatively mild start to the day.  

The weekend will turn out much colder and this same cold front will stall out in a west-to-east fashion across the Mid-Atlantic region and a couple of disturbances will ride along the frontal boundary zone.  Exactly where this boundary zone winds up will be critical in the weekend forecast for the DC-to-Philly-to-NYC corridor.  It looks cold enough on Saturday north of the PA/MD border for anything that falls to be in the form of snow, but across the DC metro region, there can be a combination of ice and snow with the possibility of an icy buildup on some surfaces.  The expected precipitation amounts appear right now to be on the light-to-moderate side with decreasing amounts as one moves north in the corridor from DC-to-Philly-to-NYC, but it doesn't take much ice to create problems. Stay tuned on this as it is still a few days away.

00Z Euro forecast map of 500 mb height anomalies ten days from now (1/21) with strong northern-latitude high pressure ridging across northern Canada; map courtesy tropicaltidbits.com

Looking ahead to next week, once this Arctic high pushes off to the east early next week, the flood gates will open for more mild air to push northward into the Mid-Atlantic region.  In fact, the warm up later next week could become an extended “January thaw” before a colder pattern resumes later in the month.  Confidence in a colder pattern returning later this month comes from the likelihood of high-pressure ridging to form across the northern latitudes in ten days or so which usually results in cold weather for the eastern US.

Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com