bluewave

We have had longer lasting December snowpack in the past with other 10”+ snowfall Decembers on Long Island without a big warm up and rain following the heavier snows. But these warm ups and rain following the heavier snows have become more common in December and the other winter months that we have had heavier snows. Unfortunately, Long Island weather records don’t go back as far as other spots across the region. But the snowfall this December isn’t that far from what used to be normal at spots with longer periods of record in the past colder climate era. Those colder era Decembers didn’t have the magnitudes of the warm ups with rain. So they had better snowfall retention for what fell relative to today.

50°+ warm ups with or without rain have become much more common prior to and following snow events here than they used to be.

I am comparing it to the old days when we would more extended snowcover with not so many warm ups with rain in between.

This has to be one of the most unusual December patterns that we have ever seen. The record low Arctic sea ice near the Kara and Barents seas has been linked to stratospheric warming events. 2025 marks one of the earliest SSWs on record. It’s also possible that this is our first December with two distinct 4-8” clipper snow events. Plus I am not even sure when the last time was that there were two 4-8” clipper events only two weeks apart during December to March. So I am not really sure yet what if anything this December will say about the rest of the winter. Since we have never had a December pattern like this before. Also note how each of the clipper events is being followed by a strong Great Lakes cutter with rain and a quick warm up.

This is probably one of the best hourly snowfall rates in CT last several years.

Really beautiful event here just east of the HVN ASOS. It came in as a very heavy wall of snow in the evening. We had 2” per hr rates for the first few hours. Then the rates decreased. Finished up here with a very respectable 5.5”.

This storm will be the test for whether they can finally discontinue the NAM. The NAM was the only model which could see the warm nose at 850 mb to 750 mb. None of the other models were very good at this. The NAM has sleet mixing in around EWR-NYC-LGA-JFK. But keeps it all snow from Suffolk NW back into SW CT and interior SE NY. So out of respect for the NAM, I will go 3-5” around EWR-NYC-LGA-JFK and 5-8” Northern Nassau to Suffolk.

Maybe the models easing up a bit on the TPV press early Jan from previous runs may allow the Southern Stream to come more into play with the +TNH and continuing -NAO.

Very impressive gradient in the Dakotas.

I think the last time Orange County had widespread 20”+ was back in December 2002. Monthly Data for December 2002 for Orange County, NY Click column heading to sort ascending, click again to sort descending. GARDNERVILLE COOP 20.1 PORT JERVIS COOP 34.0 WALDEN 1 ESE COOP 22.5 WEST POINT COOP 30.5

Models not quite as cold for the end of December and the start of January as prior runs with the core of the cold now forecast to stay to our north.

This season is going to be an interesting case study for snowy La Niña Decembers across the NYC Metro region and the rest of the season. With the storm coming in next few days, December 2025 will rank in our snowier La Niña December list of years. Most of the time these seasons got to 25”+ from Newark out to Islip. But the way we are getting this snowy December is different from the past La Niña cases. Unusually early stratospheric disruption with the record low sea ice in the Kara and Barents. The forecast is calling for a reversal of this pattern in the stratosphere after the first week of January. So it will be interesting to see if we follow up later in the season with more snow getting us over the 25” mark from Newark out to Islip. My guess is that we would probably need at least one NESIS KU event with a rapidly deepening low near the benchmark to pull this off. Since we haven’t reached 25”+ without at least one KU NESIS storm in the last 30 years. But this storm track has been inactive since January 2022 with all our snow this December coming with an unusually snowy clipper snowfall pattern that we haven’t seen in many years. The overall 500 mb pattern leading to this is quite unique for December. It doesn’t match previous Decembers. So with all the unusual influences this month, it’s difficult to say for sure we will repeat the past winter snowfall outcomes following snowy La Niña Decembers. But we can say for sure that December 2025 will go into the books as one of the our coldest and snowiest in a long time regardless of what happens after the first week of January.

The Euro is showing this coming in as a wall of heavy snow scenario where the best spots for banding can pick up 3-6” of snow in 3-4 hours with excellent rates.

The ensemble mean forecasts always kept the warmest to our SW which isn’t a surprise. But the 26th through the end of the month will verify several degrees colder. The warm up during the 17th to the 25th did beat expectations on the warmest few days which has been a common occurrence since 2011 and even prior to that. The -NAO is actually linking up with the Southeast Ridge this weekend which wasn’t originally forecast. You can see how much the models changed for Saturday from the earlier runs. But the cold high over New England is leading to a colder and snowier solution for a change. The last few years when this happened featured warmer storm tracks due to the lack of a cold high over New England. New run more -NAO linkage with Southeast ridge for rare favorable solution Old run Southeast ridge and -NAO separate

If it wasn’t for the strong -NAO, then record ridge across the Southern Plains would have expanded closer to our area.

Same with the GEFS and GEPS. I posted this in the main ENSO thread. In order to get really cold these days we need some kind of record warmth in the Arctic. If we can just get the storm track to shift south to a benchmark position in January, then maybe this can be our bounce back snowfall year which we have been hoping for.

They do a pretty good job and also stream on YouTube if not included in some cable packages. The various weather channels going to other programming reminds me of MTV getting away from their core music video business and going to mostly reality shows.

It’s tough to get much snow near the coast with SW winds.

36° and plain rain here now. Interior sections of the Northeast are doing well with this one.

This is the first time in a while that the 11-15 day ensembles have had this much of a warm bias in the East. https://frontierweather.dtn.com/verification.html

I am located just to the east of the ASOS at Tweed. 35.8° here with light rain.

Probably related to the complexity of modeling long range interactions between the stratosphere and troposphere. My guess is that this was linked to the record low sea ice Kara and Barents seas. Very intersting paper below matches the current patterns around the Northern Hemisphere. https://iopscience.iop.org/article/10.1088/1748-9326/abc215 LETTER • THE FOLLOWING ARTICLE IS OPEN ACCESS North American cold events following sudden stratospheric warming in the presence of low Barents-Kara Sea sea ice Abstract While the relationship between the Arctic sea ice loss and midlatitude winter climate has been well discussed, especially on the seasonal mean scale, it remains unclear whether the Arctic sea ice condition affects the predictability of North American cold weather on the subseasonal time scale. Here we find that, in the presence of low Barents-Kara Sea (BKS) sea ice, sudden stratospheric warmings (SSWs) can favor surface cold spells over North America at the subseasonal timescale based on observations and model experiments. A persistent ridge of wave-2 pattern emerges over the Bering Sea-Gulf of Alaska several weeks after the SSW onset, with a coherent structure from the stratosphere to the surface, which, in turn, is conducive to synoptic cold air outbreaks in Canada and midwestern USA. This highlights a planetary wave pathway relating to BKS sea ice changes, by which the stratospheric polar vortex impacts the regional surface temperature on the subseasonal scale. In contrast, this mechanism does not occur with positive BKS sea ice anomaly. These findings help to improve the subseasonal predictability over North America, especially under the background of rapid change of Arctic sea ice in a warming world.

Changed over to a mix of light rain and wet snowflakes here and 35°.

34° and light snow here with a light coating on the colder surfaces.