Hello everyone!

Special update this evening to bring you my latest thoughts on this weekend’s storm system. Right now, things are looking pretty similar to how they were this morning. 12z models did continue the westward trend but it looks like we still miss out on the brunt of the storm.

Right now, rain is already moving into parts of CT and RI for the trick-or-treaters. This is a little ahead of schedule and could have some

This storm will be divided into two parts. Part one arrives Saturday morning and lasts through Saturday evening. This will be primarily rain for our area and will involve NE winds of around 20mph gusting to 30mph. Winds during this time will be out of the NE. This is when the bulk of the QPF (the amount of liquid that will fall from the sky) will fall. After this low passes by, winds turn to the NW, precip slows and phase two begins.

Phase two involves the second low developing and passing offshore. Column saturation loss looks likely Saturday evening which should lead to precip becoming more drizzly in nature. Cold air will begin to flood southward at this point and begin to transition precip to snow. This is where the biggest forecast challenge lies. If the second low tracks more to the West, we get more QPF out of it but the snow line gets pushed farther west. If the storm passes farther east, there is less in the way of QPF but the snow line would make it farther south. This second low could even miss us altogether and bring flakes exclusively to the Midcoast.

Right now, it looks like the most likely scenario is that the first low delivers rain to most and snow to the high elevations while the second low passes farther offshore. I think most in Maine and New Hampshire see snow this evening with the most snow falling in Downeast Maine (over a foot is expected by NWS Caribou) tapering down to a few flakes flying over Southern and Coastal areas.

Snow map for Saturday and Sunday. Click to enlarge.

Winds will be a big issue as well as the storm rapidly intensifies. Expect the highest winds along the coast with gusts surpassing 50 mph at times especially Saturday night.

Peak wind gusts Saturday and Sunday. Click to enlarge.

I’ll be busy most of the day tomorrow but will likely have a mid-storm update tomorrow evening.

-Jack

Hello everyone!

Apologies for the late update, there was an unusual amount of data that had to be looked at this morning to come up with the forecast. Today will feature increasing clouds ahead of the storm. Weak warm air advection may bring a sprinkle or flurry to the mountains later in the day but otherwise, no interruptions for trick-or-treaters. Temps this evening will be falling through the 40’s.

As for tomorrow, models are slowly coming into better agreement in terms of how the storm will play out. The GFS is the most excited about the storm idea with the JMA not far behind. The Euro is still pretty excited but not nearly as much as the GFS. The NAM remains completely uninterested.

Here’s how I think it will play out. Top-down saturation of the column will allow for some light snow after midnight for the mountains. Rain moves in Saturday a little before noon at the coast and spreads NW throughout the early afternoon in association with the first low. Rain becomes more showery in nature for a brief time Saturday evening before picking up again Saturday night. Once night falls, cold air will start to flood south as the storm intensifies so a gradual change to snow can be expected starting in the mountains and eventually making it all the way to the coast by Sunday morning. All precip moves out Sunday midmorning.

Here’s my thinking on accumulations. Even heftier totals will probably fall in Downeast Maine.

Winds will be another issue as they would be anytime a storm rapidly deepens off the coast. Wind gusts will be strongest across coastal areas with gusts reaching 50mph at times. Sustained winds will be much lower however likely not making it out of the 30mph range. Power outages could be a big problem especially if snow happens to be on the branches when the wind is strongest (Saturday night).

Much cooler air moves in for Sunday with highs even at the coast not making it to 40.

-Jack