Monday, December 25, 2023

Colder Air Returns, Slight Chance of Light Snow Showers Thursday Night

Tuesday (High 55, Low 46): Partly to mostly sunny. Seasonably cold. 

Wednesday (High 56, Low 33): Mostly sunny during the day. An isolated shower is possible at night. 

Thursday (High 45, Low 30): Partly cloudy. Isolated rain/snow showers are possible at night, but are expected to remain light.

Friday (High 44, Low 29): Partly cloudy with a 20% chance of light rain/snow showers.

Saturday (High 50, Low 24): Sunny.

New Year's Eve (High 52, Low 27): Mostly sunny.

New Year's Day (High 51, Low 31): Partly cloudy with a 30% chance of showers. 

Going to make a special post even though this is Christmas evening, because some new model guidance suggests at the possibility of some snow mix Thursday night. So no, those alarmists saying we'd have a snow for New Year's did not get it right. But we might have a chance at some before then, and it's a close call as to whether it's a no-impact matter of some flurries or maybe a dusting, or whether some parts of our region might have to keep an eye out for a little accumulation. 

Let's keep things simpler than usual though. It was rainy and pretty breezy in Cullman today. Actually most of the rain cleared out in the morning, had more of it last night, and we were overcast much of the day. But the hours blend together on Christmas Eve into Christmas Day sometimes. The High was 64, and the Low this morning was 57. 

We have a closed Low way back West and a negatively tilted trough moving through the region tonight. And we have a cold front associated with that. 

There is no swift rush of cold air behind this front, but tomorrow will be a little more seasonal, a mix of sun and clouds, though I think maybe a little more sun than clouds by afternoon, a High near 55. Tonight's Low probably about 45-46.

On Wednesday we'll have another Low pressure system from out in the Missouri Valley coming our way. And there is another cold front associated with that. So we are in an active pattern here. We'll have to watch for an isolated shower Wednesday evening and night, and there could even be some snow flurries in the mix, but rainfall amounts are expected to be so light that it will be barely noticeable. Will probably still include that minimal 20% chance of a shower in the forecast. The day looks mostly sunny. High should be in the mid-50's again, maybe climbing to more like 56-57 for some of us, the Low Wednesday morning getting back down into the lower 30's.

It's late Thursday into Friday that we have to watch though with another trough dropping through the region. Behind Wednesday's front, we should start Thursday around 30 degrees and then only warm to about the mid-40's during the afternoon. With that air in place, Thursday night/Friday morning's Low is expected to be about the same. And while I'm not showing them here, forecast soundings do support a mix of rain and snow at times overnight Thursday into Friday morning. If you even look at the GFS model guidance, precipitation type, it does show pockets of light snow scattered across the Tennessee Valley in the dark hours of Friday morning. The chance of precipitation Thursday night/Friday morning is only 20%. And any rainfall is expected to be very light again. But a very light amount of rain when the whole thermal profile is below freezing can translate into a decent dusting of snow or even a light accumulation sometimes. If this happens, it would be most likely along the Cumberland Plateau of Tennessee, and maybe in some of the higher elevations of Northeast Alabama. 

I wouldn't get overly concerned about it. Even if this plays out and some of get some accumulating snow, it looks like the amounts would stay light. And I would not make a special grocery trip unless you're already nearly out of supplies. This is a dicey situation, just a low chance of some snow showers that could be anything from a few flurries to a light accumulation. And even if that low chance plays out, it is not expected to snow (or even rain . . . or drizzle) everywhere in our region. 

Then after that trough is through with us, Saturday looks sunny again with a High near 50, should start the day down in the 20's, probably mid-20's.

Then Sunday is New Year's Eve. Looks like we stay sunny with a High of about 50 or so, the Low in the upper 20's. 

And as much as I've wanted to forecast dry conditions for New Year's Day, we will actually have to keep an eye on things. Not only this WPC map but the latest guidance from the GFS and ECMWF show a decent chance of precipitation now for next Monday. Let's take these systems one at a time, but the High is expected to be near 50, Low near 30, so usually with that, chances of any snowfall are pretty low, or it'd be a rain/snow mix that is unlikely to lead to any accumulations. It's really too soon to make that call, but since people are already speculating, I'd like to point out that none of this is anything to get bent out of shape about. Even in the areas most likely to get snow along the Cumberland Plateau on Thursday night, the estimates are up to about a half-inch. That would just be a pretty snow for some people, unlikely to cause any negative impacts. So please do not be lured by the hype train. The model guidance has not been all that consistent for New Year's anyway. And you have to think about the overall trends of model runs from day to day, not just what the latest runs are saying. The computer models usually get things wrong, and you have to figure out what they are getting wrong and why, and reason through it. 

For now the Weather Prediction Center is thinking the chances for any significant snow accumulation will be up in Western North Carolina up into Virginia on Thursday night/Friday morning. So yes, some snow is possible in Tennessee, mainly along the Cumberland Plateau. And we could even see some in North Alabama. But accumulations, if any, are expected to be on the light side. Of course we'll need to monitor the trends just in case anything were to make it look more concerning for anyone in the region, but as of right now, I doubt many places will even see as much as one inch of snow, even in the higher elevations. This just doesn't look like that big a deal. If it amounts to anything, it'll probably just give some kids who are out of school some pretty snow to look at in the yard. 

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