1:45 PM | *Snow arrives towards morning and continues through the morning hours and it could include a brief, heavier burst…the return of more sustained cold*
Paul Dorian
High-resolution NAM (3-km) forecast maps from Monday evening to Tuesday evening brief, but heavier burst of snow for DC, Philly metro regions; maps courtesy NOAA/EMC, tropicaltidbits.com
Overview
The current stretch of generally warmer-than-normal weather in the Mid-Atlantic region that began a couple of weeks ago comes to an end this week and we’ll return to a more sustained colder-than-normal pattern for much of the month of February. One cold front will arrive late tonight and it’ll usher in a cold air mass for the next couple of days and then a second cold front will arrive by early Friday with another cold air mass to follow in its wake - each of these fronts can bring some snow to the DC-to-Philly corridor.
Upper-level (500 mb) forecast map by the 12Z NAM (3-km) for early Tuesday with vigorous energy over the Mid-Atlantic region; map courtesy NOAA/EMC, tropicaltidbits.com
Discussion
Temperatures today have reached the 40’s in DC and Philadelphia and strong surface low pressure is now riding along a frontal boundary zone just off the Mid-Atlantic coastline. The next several hours can feature some rain at times in the immediate I-95 corridor from DC-to-Philly and to the coastline as the western edge of the precipitation field is well inland from the low pressure center. Early tonight, there can actually be some snowflakes mixing in at times across NJ and portions of the Delmarva Peninsula, but ground temperatures are above freezing so accumulations are not likely. The "low pressure-induced" precipitation will then end before midnight and it'll be time to look upstream for the next system.
Our current stretch of warmer-than-normal weather in the Mid-Atlantic region is coming to an end this week (map shows 2-meter temperature anomalies for the last 14 days); map courtesy Weather Bell Analytics
Later tonight, colder air will push into the region and there will be a vigorous wave of energy in the upper-atmosphere moving overhead at about this time and this will likely result in some snow breaking out towards daybreak and it should last through the morning hours in the DC-to-Philly corridor. As the upper-level wave of energy rounds the base of an intensifying trough, mesoscale banding may develop on Tuesday morning which could result in brief bursts of heavier snow for some spots. While this won’t be a significant snow event, it may have an impact on the morning commute due to its timing and any burst of heavier snow could stick in a hurry. Accumulations should end up being on the order of a coating to an inch or two in the DC and Philly metro regions and temperatures tomorrow should hold in the 30’s - similar accumulation amounts expected in the NYC metro region as well.
After a couple of dry and cold days, the next front will close in on the area by Thursday night. Low pressure is likely to form along this next frontal boundary zone and this setup could result in “rain-changing-to-snow” Thursday night into early Friday for the I-95 corridor. Following this late week frontal passage, cold air will rush in for the weekend and highs on Saturday may struggle to pass 30 degrees. This chill is then likely to stick around for awhile and there can be some more snow chances by the early part of next week.
Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com
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