Space Weather

Wednesday, November 20, 2024

The last dry day before much needed rain.

 

I’ve been talking about this storm for over a week now, so all y’all should know it’s coming.




The surface chart shows our system in the Midwest. This is going to deepen and dive toward the Middle Atlantic. We will see a coastal nor’easter develop around the Delmarva Peninsula then this will deepen as in moves off the New Jersey Coast, on its way to track over New England. The storm looks to become stalled for Friday into Friday evening, be for starting to slow move to the east Friday night and Saturday.

This is going to bring widespread rain amounts of 0.50 to 2.0 inches, with localized abound of 2.5 inches possible. This won’t be a drought buster, but it will put a decent dent into things. Rain will be heavy at times.  Winds are going to be gusty across the region.

Cold air is going to wrap in behind the storm, changing rain to wet snow for the Appalachians in Kentucky, Virginia, West Virginia, Snow will extend up through the Laurel Highlands of Pennsylvania and across much of northern Pennsylvania, then a large part of New York State into northern and western New England. Those across the Middle Atlantic, New York City, Long Island, into southern and eastern New England will see primarily a cold rain, with maybe a few flakes mixing in.

This will be elevational, with the snow line starting around 1500 feet. The lower elevations could see some snow mixing in across parts of the region, but accumulating snows are likely for middle to upper elevations. The peaks in the Catskills, Adirondacks, Greens, and Whites could see upwards of a foot of snow.



The storm will be slow to exit, because of the block in place. As that coastal storm develops, it will expand the precipitation shield. so, we can expect rain/snow showers to expand to the west. The rain/snow showers will extend into the Weekend.  Here is a map, that shows my general thoughts on possible snow amounts.  The nor’easter will be pulling way on Sunday.

The cold air coming in behind the storm Friday night and Saturday, will cause west to northwest winds to blow over Lake Erie and Lake Ontario, Will allow for some lake enhanced snow to develop downwind of the Big Lakes, the temperature profile isn’t supportive for significant lake snows to fall. But it is possible some broken lake effect bands could form that could drop a few inches.

Monday will see high pressure move in. Then for Tuesday a weak moisture starved cold front will move through. High pressure looks to move in overhead for Wednesday.  The high pressure looks to hang around for Thursday.  Sunday into Thursday looks to see lake effect rain/snow showers downwind of the Great Lakes. These shouldn’t be very heavy, but they might slow you down as you travel.

 




3 comments:

  1. Rebecca, what do you mean by the temperature profile affecting LES? Profile through the atmosphere?

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  2. When cold dry air moves over relatively warm water; the air picks up moisture and warmth and rise due to evaporation. When the air moves back over the land (like the Tug Hill) the air cools back down, as the air can no longer hold all that moisture, and lake snow falls. The greater the temperature difference between the air and the water the more water vapor the air can take in, resulting in higher amounts of snow and a bigger storm. The perfect environment is when the air temperatures at 850 mb (5,000 feet) above the lake is at least 25 degrees colder than the lake.

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  3. So Great to see a Hand Made Snow Map by Rebecca.I would be bummed that we have low snow totals buy with the fires burning for a week or so and burning in areas that are next to impossible to get to,we can do without a white Thanksgiving, we haven’t had one of those in so long that it doesn’t matter. Still my dreams are interrupted by snowfall Christmas Eve day Christmas Eve and Christmas Day. I’m sure it will be about 40° out but one can dream. Now for a question, why does it seem that when you have an elevation snow event that the snow line usually starts at 1500 feet is that where change in the atmosphere happens or is that a different level of the atmosphere. Thank you

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Thank you for taking the time to comment, I will answer as soon as I can.