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Don Paul: It's going to look (at least a little) like Christmas

Based on (1) a White Christmas being defined in climate statistics as having at least 1 inch of snow on the ground on Christmas and (2) new model input, I’m more confident most or all of Western New York will have a White Christmas on Tuesday.

No, it will not be the result of some whopper snowstorm, and heavy duty shoveling will probably not be necessary in most spots. But I believe we will have snow on the ground before Christmas Eve, followed by a seasonably wintry Christmas Day.

Heck, if I change my mind about all this, I’ve got one last chance to clean up my forecast Sunday night on WKBW when I do my final weathercasts there at 6 and 11 p.m.

Blatant TV plugola aside, Friday morning’s model runs show good agreement on at least some minimal accumulated snow on the ground across Western New York. Even by late Saturday, some lake effect will be adding up to several inches on the hills of ski country, with lesser but still measurable amounts to the north on the Niagara Frontier.

Here is a high-resolution National Weather Service model showing accumulated snow by 7 p.m. Saturday:

(TropicalTidbits.com)

And here is a more aggressive National Weather Service model showing greater amounts on higher terrain.

As is typically the case, model output is not unanimous for the Niagara Frontier by 7 p.m. Saturday. Lower amounts are put out by still another weather service model.

By Monday morning, this next model shows heavy totals over higher terrain and more meaningful totals up to the north.

If I were a cherry-picker engaged in wishcasting, I’d say “Oooooo! The real deal!” Alas for snow-lovers, my years of pattern recognition and examination of model ensembles leads me to believe this particular model is overdoing the snow amounts.

But that’s just through Saturday. By Sunday evening, another weather service model shows a weak but organized low pressure system bringing another coating.

By Christmas morning, the newer experimental version of the American/GFS shows a thin coating, but a coating nonetheless, near the lakes and in the metro area, with more significant amounts at higher terrain, as to be expected.

The Canadian/GEM is somewhat snowier than the American model:

(TropicalTidbits.com)

Christmas Day is four days out from this writing. In that time range, ensembles (multiple runs of the models in clusters) and the means/averages of those ensembles can often produce a more reliable precipitation range than just a single run of a single model. With that in mind, the ensemble mean of the American/GFS indicates around 4.5 inches of accumulating snow by Christmas Day for Buffalo.

A shorter-range ensemble mean from a different model shows 3.4 inches for Buffalo by Monday evening. (Unfortunately, these ensemble “plumes” don’t graphically translate well because they are so esoteric and complex, as well as being difficult to to transfer in a useful format in print.) I'll mention briefly extended range guidance still suggests a transition to a considerably colder pattern beginning around mid-January.

So, let’s say the ensemble means are onto something with 3.4-4.5 inches of accumulating snow over a three- and four-day period. I have my doubts that much will actually be on the ground on Christmas Day. Because temperatures are not going to be especially cold, with daytime highs moving above freezing, some loss of snowpack can be expected. The snow will be somewhat more water-laden at those temperatures and will compress of its own weight. Compression produces warming that causes melting at the base of the snow. In addition, there will be some melting during the day at the top of the snowpack.

All that said, this should still leave a coating over most or all of Western New York for a white Christmas. Besides, there’s always the chance that the one model I said was probably overdone might be the right solution, and voila!

Now, THERE’S some first-rate cherry-picking for you, gang!

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