Monday November 20, 2023

11/20/2023

Potentially significant interior snowfall event
on the way Wednesday

The timing of this is not good for what is typically the busiest travel day of the year. Given the fact that this could potentially be the first widespread interior snow event of the season brings concerns as well. The annual meeting of the Summer Tires Club could be rough for those trying to get to where they need to go. For those travelling on Wednesday, expect accidents and a slow drive. For those flying into the regional airports, there is potential for flight delays, with a low risk of cancelations.

The set up

Monday 6 AM to Thursday 10 AM - Using the precipitable water forecast idea as a guide, high pressure working into the region Monday brings the cold air in for Tuesday. A spiking ridge shoots northeast from the southwest which brings the juice needed for precipitation. The good news here is the trough moving in behind the ridge is positively tilted at the onset, shifts neutral over the region, then goes negative out to sea. Nova Scotia is likely to get a decent storm out of this. As for Maine, we'll have impacts to deal with, but not to the level of our Maritime neighbors.

A coastal hugger track appearing the most likely scenario

The one key feature in storm tracks and a fair clue of what the precipitation type outcome could be figures around the benchmark point. The is located at 40° N latitude, 70° W longitude. I will refer to this often. In this set up here, the cluster of European ensembles and the mean are well inside of the benchmark "B" on the graphic. This is good news for the ski hills needing snow enhancement from Mother Nature in time for Thanksgiving, but bad news for driving. If you are heading for the slopes, travel on Tuesday or Thursday is my advice. For the coast, this may start as snow, but will change to rain fairly quickly. How far inland the coastal front goes which will separate who gets snow and who does not is still to be determined.

Timing

Tuesday 7 PM to Thursday 10 AM - You are on notice that the Wednesday morning commute is likely to be trash. For the interior, it will be snowing. For the coast, it will rain, that could be heavy at times. This could go on all day. The interior may flip to a light wintry mix or rain as precipitation begins to end later in the day, but it is looking like a mainly snow event at this point. Precipitation ends from west to east Wednesday night, with some light rain and/or snow showers exiting eastern and northern areas Thanksgiving morning.

Precipitation potential

Given the potential track of the storm along with the injection of moisture from the sub-tropical jet, coastal areas could get a soaker. A southeast wind that will gradually increase as the low intensifies over the Gulf of Maine could throw moisture and heat from the 50° ocean temperature into the coast. There is also the risk of thunder here with the cold air around. Dare I say there may be the chance of thundersnow for the interior? That is possible, too.

The coastal front dictates where the rain / snow line sets up which brings the greatest level of uncertainty to the forecast. For now, expect a couple of sloppy inches, and stay tuned. This is likely to be a sticky wet snow for the western mountains, and somewhat drier to the north around the Allagash. This could bring some power outages. If the snow doesn't cause power loss, the wind on the backside could bring wires down also.

Expect some upslope snow showers for the mountains through Saturday as reinforcing waves of weak frontal boundaries pass through.

The wind

Tuesday 1 PM to Sunday 7 PM - A gusty southeast wind is on tap for Wednesday, then shifts to the northwest early in the morning for Thanksgiving. Expect a gusty wind to persist from the northwest through Saturday, then settle on Sunday. Wind chill temps by the weekend could be in the single digits above and below zero for the mountains, teens to low 20s elsewhere.

Temperature and outlook through Sunday

Below normal temperatures have generally been the rule for November and that trend continues. The mountains, you are in winter mode. For the coast, you're getting there. After the storm on Wednesday, the rest of the holiday weekend appears storm free. There is a slight chance of a storm in the Monday / Tuesday period a week out, but it's too early to carve that into stone.

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NOTE: The forecast information depicted on this platform is for general information purposes only for the public and is not designed or intended for commercial use. For those seeking pinpoint weather information for business operations, you should use a private sector source. For information about where to find commercial forecasters to assist your business, please message me and I will be happy to help you.

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