Rain and wind likely Sunday, winter arrives next week

High pressure over Eastern Quebec will cause cold air damming over the region tonight, with cold air funneling toward our area. A mid level shortwave and weak warm front are on their way by Saturday morning, however, with the first light round of precipitation ahead of a significant storm system.  As this disturbance approaches our area, some very light snow, sleet, and freezing rain is expected across the interior and higher elevations. Temperatures there will be hovering below or near freezing — causing the potential for slick roads.

A deepening storm tracking over the Eastern Great Lakes will send a stronger warm front — and then  a cold front — through the region late Saturday night and Sunday. Lifting will be aided by a strengthening southeasterly low-level jet and precipitable water values between 1.00 to 1.50″.  This will cause periods of rain starting late Saturday night, becoming heavy at times during Sunday morning and early afternoon.  An isolated thunderstorm can’t be ruled with elevated instability.

18z NAM 51hr

NAM model showing heavy rain over the region on Sunday morning

There will be strong pressure gradient between this storm and strong high pressure departing over Newfoundland. Model guidance continues show winds between 50kt to 70kt between 850mb and 950mb on Sunday morning. However, forecast soundings also show a weak low-level inversion that will likely prevent much of these winds from reaching the surface. At this time, we still anticipate winds gusts to around 40mph, especially near the shore. Any thunderstorm could still bring stronger winds to surface. With the new moon this weekend, tides will be astronomically above normal. A strong southeasterly flow could some minor to moderate coastal flooding and beach erosion is possible at high tides during Saturday night and Sunday morning.

18z NAM 45hr 925mb

The NAM showing winds at 925mb level between 50kt to 70kts.

A mild southerly flow will cause temperatures to remain steady or slow rise through 50s Saturday night. On Sunday, temperatures could rise into upper 50s to lower 60s. As we have seen, with every warm surge this winter, record highs will be jeopardy again. These are record high temperatures for Sunday:

Central Park,NY 60 1876
LaGuardia,NY 59 2000
JFK Airport,NY 55 2000
Newark,NJ 59 2000
Islip,NY 56 2000
Bridgeport,CT 55 2000

Rainfall should taper off to showers or drizzle later Sunday afternoon, as the cold front moves past the region. Partly cloudy skies are expected before an artic front will arrive later Sunday night. Temperatures behind this front will drop quickly into 30s and 20 by Monday morning. Mostly sunny skies will do little help temperatures rising on Monday. Another artic airmass will be over region. Model guidance shows 850mb temperatures -10°C to -15°C

12z GFS for showing a low developing New England Wednesday Morning

12z GFS for showing a low developing near New England Wednesday Morning with snow showers over the region

On Tuesday, our attention will turn to an Alberta Clipper. a 500mb shortwave from Canada will be digging downstream off the ridge over Western Canada. The primary low with this system will be tracking over the Great Lakes than transfer it energy to a secondary low developing near the Northeast coast. This could cause a significant snowfall for parts of Central and Northern New England.

For our region, it appears likely at this time that this storm will develop too late for major impacts. Some snow showers at least are possible on Tuesday night and Wednesday. With temperatures falling into upper 20s to lower 30s, some light snowfall accumulations are possible as well. However, there are some model differences and uncertainties with how much amplification will occur. The Western Canada ridge and developing -NAO pattern could also lead to shortwave energy digging further south and amplifying more. We’ll continue to monitor this system closely over the next few days.