Friday Briefing: Arctic Cold Then Northeast Winter Storm Threats Sunday & Wednesday

Happy Friday! Rain overnight ended as some snow across over the region, early this morning. Interior locations, including parts of Northwest NJ, the Poconos and Catskills saw few inches of snow. Little or no snowfall accumulations occurred elsewhere, as the best dynamics and moisture moved quickly offshore, with the cold front. As a result, snow was mostly light and ended after hour or two, with temperatures still above freezing.

However, there is threat for a flash freeze, as much colder air rushes in behind the cold front today. Temperatures will be mostly in the middle or upper 20s for the rest of the day. So any standing water could freeze into some this morning. Some patchy black ice will also form on any wet, untreated roads. So use more caution driving roadways, especially during this morning.

Otherwise, skies clear for more sunshine with some breezy conditions for the rest of the day. Northwest winds will be gusting to between 25- 30mph, will make for wind chills in the single digits and teens. Mostly clear skies and diminishing winds are expected tonight.  But it will be frigid with overnight lows will from middle teens over New York City and other urban areas. Elsewhere low temperatures will range from the single digits to lower teens.


3km NAM model with low temperatures overnight.

Saturday will be very cold and partly sunny with high temperatures only in the upper 20s to lower 30s. Then clouds will begin increasing Saturday night, as arctic high pressure moves offshore and the next storm system approaches from the west. It will still be very cold. But more southerly winds along with cloud cover will keep temperatures from dropping out of the 20s.

On Sunday a primary low pressure tracking near the Eastern Great Lakes, and another secondary low may also form and track off the Mid-Atlantic coast. This may support more snowfall over Northern and Central parts of New York and New England. However, warmer air will still eventually surge northward with this system, without high-latitude blocking or high pressure to the north. Therefore some snow or wintry mix that changes to rain is likely over much Eastern Pennsylvania, New Jersey, Southeast New York and Southern New England.  Some light snow accumulations are possible before the changeover, especially away from the coastal sections.

Then precipitation comes to an end during Sunday night as this storm exits into Southeast Canada. Some tranquil and colder weather returns again on Monday and Tuesday, behind this storm system. However an active, progressive pattern continues with another storm system likely impacting the Northeast and Mid-Atlantic regions by Wednesday. There is some uncertainty, as usual at this juncture, on how this storm will come together again. But some snow or wintry mix is possible again as precipitation begins on Tuesday night or Wednesday.


Overnight GFS model showing a storm system with snow, wintry mix and rainfall over the Northeast and Mid-Atlantic on Wednesday

But again with no high-latitude blocking or high pressure to north, the airmass will likely moderate again as this storm system approaches. Thus the I-95 major cities and coastal areas likely to see more rain on Wednesday. While snow or wintry mix with more accumulations may continue over the Interior, depending on track or evolution of this storm system. More details with this storm system, will become clearer as the guidance resolves shortwave energy timing and spacing. So stay tuned for more updates and have a nice weekend!