An Active Stretch Of Weather Begins

Hello everyone!

Today’s snowfall is kicking off an active pattern for at least the next 10 days. Snow will change to a messy mix tonight before moving out tomorrow morning. Temps will fall from near 50 Wednesday afternoon to right around 20 by Thursday morning as snow moves in associated with our next system. After some wind blown fluff Thursday, we’ll get a day off Friday before a clipper system approaches Saturday. Sunday morning will be the calm part of the weekend before more snow/mix arrives with a system Sunday night into Monday morning. Another system may be showing up on the horizon for the middle/latter part of next week but it’s too far out to say what any potential impacts from that may be.

This current system has been slightly misbehaved, the first round having arrived and departed early while the second round dragged its feet in getting here. There wasn’t a lot of data that supported a break in the action today but it happened going to show you that despite our best efforts as forecasters, mother nature is the one really in charge.

HRRR Model Showing Snow Intensifying And Changing To Sleet/Freezing Rain Tonight Into Tomorrow Morning. Credit: Weathebell
HRRR Model Showing Snow Intensifying And Changing To Sleet/Freezing Rain Tonight Into Tomorrow Morning. Credit: Weathebell

The rest of this storm does look to be fairly straightforward with the only major challenge yet to figure out being the timing of the freezing rain -> rain transition. Based on the above model simulation, it appears as though that may not occur until after most if not all the precip has left though other guidance suggests the coastal plain may warm up before then. Either way, a period of ice is likely to make the morning commute slick but temps in the 50’s will make sure any icy spots melt away for the PM commute. After that, temps take a nosedive after dark and end up back in the teens for Thursday morning. That’s when the next round of fun starts.

12Z GFS Showing A Near Perfect Setup For A Large Coastal Storm Thursday. Image Credit: Accuweather
12Z GFS Showing A Near Perfect Setup For A Large Coastal Storm Thursday. Image Credit: Accuweather

Everything starts at 500mb when it comes to coastal storms and all signals are pointing to a fairly impactful event. The all important trough orientation is forecast to be negative meaning the slope of the trough axis is negative. This allows for the energy that forms the storm to pull out ahead of the main trough where S/SE winds can push it right up the coast. The 500mb pattern is extremely conducive to a more westerly storm track which is why I’ve gone towards the upper range of guidance for snow totals (see map below).

12Z GFS Showing A Jet Stream Pattern Favorable For Rapid Intensification. Image Credit: Accuweather
12Z GFS Showing A Jet Stream Pattern Favorable For Rapid Intensification. Image Credit: Accuweather

The jet stream will be oriented in such a way that rapid intensification of the low is supported. While not textbook, there will be two jet streaks coupling to create enhanced divergence in the upper levels as we go through the morning Thursday. Notice the overlap between the right entrance region of the poleward jet and the left exit region of the equatorward jet. This is the area in which divergence is maximized. It lines right up with the coast of New England which is another factor that would support a low track closer to the coast.

12Z GFS Showing Lots Of Upward Motion In The Area Thursday Afternoon. Image Credit: Accuweather
12Z GFS Showing Lots Of Upward Motion In The Area Thursday Afternoon. Image Credit: Accuweather

Looking towards the mid levels, the exact placement of strong upward motion will determine who gets the heaviest banding. The jackpot is currently forecast to reside over MA and SNE leaving us with moderately heavy snowfall as opposed to very heavy snowfall. However, a tick NW in the storm track as supported by the 500mb maps would mean those heavier bands would move in our direction. There’s a fine line to walk here and I suspect we’ll have more confidence by the time tomorrow rolls around.

Forecast Snowfall For Thursday
Forecast Snowfall For Thursday

Here’s my thinking for total snowfall Thursday. There’s room for these numbers to go up depending on the exact track. I also think this storm will follow the typical pattern of sharp gradients on the NW edge so a downward adjustment is possible across the mountains. I’ll finalize these numbers tomorrow.

12Z GFS Showing Our Next System Saturday. Image Credit: Weatherbell
12Z GFS Showing Our Next System Saturday. Image Credit: Weatherbell

Snow will move out Thursday evening leaving a cold and breezy but dry Friday. By Saturday though a clipper system will approach from the west bringing with it more snow. This system looks colder than the one today and lighter than the one forecast for Thursday. A general 1-3″ looks to be a solid early guesstimate on accumulations as guidance is fairly locked in at this point. A little coastal enhancement could develop Saturday night which may result in some moderate snow but otherwise this looks like a fairly benign system.

12Z GFS Showing Another Storm For Sunday Night Into Monday. Image Credit: Weatherbell
12Z GFS Showing Another Storm For Sunday Night Into Monday. Image Credit: Weatherbell

The clipper will move out Sunday morning leaving about 12-18 hours of calm before our next storm arrives Sunday night. This one will track right over us, approaching from the west then redeveloping offshore. The exact timing/details have yet to be determined but we have cold high pressure in place and a sharp frontal zone to our south so this one looks fairly likely to cause some trouble as we begin the next week. We’ll discuss amounts as we get closer.

The next storm in our parade is scheduled for the second half of next week but is way too far out to discuss potential timing/impacts/amounts. We’ll keep an eye on it as we get closer!

Beyond that, all indications are that we stay in an active pattern for at least the next couple weeks. Welcome to winter’s comeback!

-Jack

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