12:45 PM | ***Next threat of wintry precipitation in the Mid-Atlantic comes early Sunday in the form of freezing rain and/or sleet - just ahead of an impressive Arctic blast for early next week***
Paul Dorian
12Z NAM (high-resolution version) surface forecast map as of 10AM Sunday, January 9th, with freezing rain (shown in orange) in much of the Mid-Atlantic and sleet (shown in purple) in New England. Map courtesy NOAA, pivotal weather
Overview
Accumulating snow ended this morning across the Mid-Atlantic region and, in its wake, there are quite windy and cold conditions with partial sunshine. The next threat of wintry precipitation looks like it will come early in the day on Sunday, January 9th and this time, it will likely be in the form of freezing rain and/or sleet. The opportunity for icing will come on Sunday morning as milder air tries to advance northeastward into what will be a cold and dense air mass. It doesn’t take much in the way of icing to have an important impact on travel conditions. Whatever precipitation does fall on Sunday, it will certainly be followed by an Arctic outbreak for the early part of next week that will feature some very impressive cold for the northeastern quadrant of the nation.
Surface temperatures are likely to be at or slightly below the freezing mark early on Sunday (7AM) in much of the Mid-Atlantic’s I-95 corridor as depicted here by the 12Z NAM. Map courtesy NOAA, pivotal weather
Details
In the wake of the accumulating snow event, very cold air is now pouring into the Mid-Atlantic region riding in on strong NW winds and temperatures late tonight are likely to drop well down into the teens in many spots along the DC-to-Philly-to-NYC corridor. With high pressure in control on Saturday, there will be some sunshine and less in the way of winds compared to today, but temperatures will remain well below-normal for this time of year. Skies are likely to start off on the clear side early tomorrow night allowing for radiational cooling and temperatures will respond accordingly by dropping rather sharply. By late tomorrow night, clouds will lower and thicken as milder and more moist air begins its push into the northeastern part of the nation.
12Z NAM (high-resolution 3-km version) forecast map of total accumulated freezing rain amounts (in inches) for the Sunday event. Map courtesy NOAA, pivotal weather
On Sunday, a strong Arctic cold front will be approaching the Mid-Atlantic region from the Great Lakes region. Out ahead of this front, slightly milder air will try to push northeastward into the Mid-Atlantic, but it will encounter a stubborn dense, cold air mass that will initially be quite reluctant to give up its ground – a classic setup that can lead to freezing rain and/or sleet. With temperatures expected to be at or slightly below the freezing mark on Sunday morning in the I-95 corridor combined with the cold ground from the recent snowfall, any liquid rainfall that reaches the ground is liable to freeze on contact at ground-level. This potential icing on Sunday morning can occur in the immediate I-95 corridor region, but it is probably more likely in the normally colder suburban locations to the north and west of the big cities. By afternoon on Sunday, milder air should win out in its battle to force a retreatment of the low-level cold, dense air to the north. Temperatures should climb to well above freezing by later in the afternoon on Sunday and any precipitation that falls at that time would likely be in the form of plain rain.
An Arctic blast early next week will tend to peak on Tuesday in the Mid-Atlantic/NE US when temperatures should bottom out at some 15 or 20 degrees below-normal for this time of year. Map courtesy NOAA, tropicaltidbits.com
After the passage of the strong Arctic cold front, winds on Monday will increase in strength from the NW in the Mid-Atlantic and Northeast US. This flow of air will likely activate the “Great Lakes snow machine” and the result will be numerous snow showers and snow squalls just downstream of the lakes and perhaps a few of these can make it all the way into the I-95 corridor late in the day on Monday. On Monday night, temperatures will plunge well down into the teens for late night lows as the coldest core of the Arctic air mass arrives and it will be in place on Tuesday as an Arctic high pressure system pushes nearby. In fact, temperatures on Tuesday are likely to be confined to the 20’s for highs in DC, Philly and NYC – some 15 to 20 degrees below normal for this time of year - impressive cold indeed.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com