Friday 12:00 PM | ***Wintry precipitation threat late Sunday/Sunday night…significant threat by the middle of next week with accumulating snow likely***
Paul Dorian
A light wintry precipitation event is probable on Sunday night in the Mid-Atlantic region with snow showers likely north of the PA/MD border and a mix of rain and snow showers to the south of there. Map courtesy NOAA/EMC, tropicaltidbits.com
Overview
Low pressure will ride along a stalled out frontal boundary zone on Saturday moving in a west-to-east direction and its precipitation field will likely not extend farther north than central Virginia with little or no impact expected in DC, Philly and NYC. A second low pressure system will likely result in some snow or snow showers late Sunday in areas north of the PA/MD border and a mix of rain and snow showers to the south of the Mason-Dixon Line.
By the middle of next week, we’ll have to deal with a third low pressure system - easily the most intriguing and potentially significant - as this one will have the plenty of moisture available to it. In addition, the mid-week storm is likely to have cold air in place ahead of it with strong, cold high pressure positioned to our north and northwest. The overall pattern that is unfolding for the mid-week storm raises the chance for an extended period of frozen precipitation in the DC-to-Philly-to-NYC corridor including accumulating snow.
The setup for the mid-week system will begin with a “banana-shaped” high pressure system to our north and northwest by Tuesday evening. This feature raises the chances for “locked-in” low-level cold air and frozen precipitation at the onset of the mid-week storm. Map courtesy NOAA/EMC, tropicaltidbits.com
Weekend threats
A strong cold front will slide through the Mid-Atlantic region late today and will then stall out across the Carolinas by early tomorrow. Low pressure will ride along that stalled out frontal boundary zone on Saturday and likely spread snow as far north as central Virginia, but it is likely to have little or no impact north of there. A second wave of low pressure will then impact the Mid-Atlantic region late Sunday and Sunday night and this one looks like it may result in some snow showers or even steadier snow to the north of the PA/MD border and a mix of rain and snow showers to the south of there. In all areas, sleet and/or freezing rain can be mixed into the picture as well. Small snow accumulations of up to a couple of inches are possible across eastern Pennsylvania and central/northern New Jersey with this late weekend system, but borderline temperatures south of the PA/MD border will likely lessen the chance of any snow accumulations down there. High pressure will then begin to build into the Mid-Atlantic region by Tuesday with seasonably cold conditions.
Mid-week system will have plenty of available moisture and with strong, cold high pressure to our north, frozen precipitation at the onset is a good bet; map courtesy NOAA/EMC, tropicaltidbits.com
Significant threat for the mid-week
By late Tuesday, a “banana-shaped” area of high pressure - and very key player here - will extend from the Northern Plains to the Northeast US and, at the same time, there will be lots of moisture pushing northeastward from the Gulf of Mexico to the Mississippi and Tennessee Valleys. By late Tuesday night or early Wednesday, accumulating snow could very well break out in the I-95 corridor of the Mid-Atlantic; especially, given the fact that a strong high pressure will be positioned to our north and acting as an anchor to a cold, dense air mass.
12Z Euro snow depth forecast map as of 3AM Thursday, February 21; courtesy ECMWF, weather,us
By later Wednesday, some milder air will advance northward along the east coast – at least into the upper part of the atmosphere – and this could result in a changeover from snow to sleet and then ultimately perhaps to plain rain in the DC-to-Philly-to-NYC corridor. Significant accumulations of snow are certainly on the table in the Mid-Atlantic region in the late Tuesday night/Wednesday time frame before any potential changeover to sleet and/or rain.
Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com
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