Dec 23: Snow Or No Snow?

Today was a mainly cloudy day across the area as some snow showers from a storm affecting New England reached the eastern parts of the area and brought some reports of light accumulations there. Temperatures were generally in the lower to upper 30s across the area with windy conditions observed. Temperatures over the next several days will slowly cool down ahead of a potential storm on Sunday.


Sunday-Monday Storm Discussion: Snow Looking Less Likely

Over the last few days, today's model runs were mentioned as important runs as once the energy came onshore, the models would be able to sample it better and give us a better idea of where the storm could track. Today's models did start to agree on a general track area, which is leaning towards the out to sea scenario rather than the western scenario that would have brought a large snowstorm to the coast, but what especially helped lower snow chances was the ECMWF model that was the most consistent over the last few days with a big snowstorm, which went much further east today - barely bringing any snow to NYC when its runs yesterday had well over a foot of snow.


Model Analysis: As mentioned previously, the models started agreeing on a general track area today. The most noticeable trend came from the ECMWF, which is rather surprising as up until today it was the most consistent model, showing a slow and further west storm bringing a large blizzard to the Interstate 95 corridor. Its 00z (night) run was only slightly east of yesterday's 12z (afternoon) run, but today's 12z run had a huge east shift, keeping most of the snow offshore. While its next 2 runs will help determine if this was an off run or not, the fact that most of the models are also this far east makes it more likely that this could be a trend towards the general consensus, not an off run.

The GFS model, which trended west yesterday, is now one of the westernmost solutions, with its 18z run showing nearly 2-4 inches of snow in the immediate NYC area. Its morning 06z run though was even more west, with slightly higher snow amounts in NYC and over 10 inches of snow in far eastern Long Island. The GFS, however, is still not very consistent with the exact storm track, which is shown by its 12z run which was out to sea. The GGEM and UKMET models are still showing a solution that is out to sea, with the GGEM even further east than yesterday.


Forecast Track: There are still no major changes with the forecast scenarios from yesterday, however the eastern track that was shown on the map two days ago now appears to be more likely over the western track. The timing remains the same as yesterday, with this being a Sunday to Monday storm. The exact track mainly depends on the storm's timing and phasing, which we will likely have a better idea on over the next day or two.


Thoughts For NYC Area: The latest models today, as previously mentioned, trended away from a big snowstorm, especially the most reliable model, the ECMWF, and with the new consensus further east, I decided to lower snow chances for the area. Even though the 5-Day Forecast was not updated, I am currently putting the western parts of the area with a 30% chance of snow, the immediate NYC Area with a 40% chance, and Long Island/S CT with a 50% chance as there could be several inches of snow in Long Island/S CT if the western tracks verify. These percentages are still not final and are subject to change.

For the scenario map above, I used a scenario similar to that of the ECMWF and the GFS models, which are the western solutions at this time, to show that eastern Long Island and eastern New England have the best chance of accumulating snowfall from this storm if the western solution verifies. If they trend west from there, several inches of snow may extend into the area in the light blue, and while this is unlikely at this time, this potential will be watched as the models are still uncertain with the smaller details such as precipitation coverage area and intensity. It is still very possible, however, that the storm ends up going well out to sea and missing the area, which in that case, the area would only see scattered snow showers. At this time, my probabilities are based on a solution in between the eastern and the western solutions, which would favor at least some light snow in the eastern parts of the area, but this is subject to change based on tomorrow's model runs.

It is important to note, however, that the models are still having difficulty handling the storm's energy and the phasing and timing of the storm, with the models not too consistent with the exact track, especially the GFS. While there is a better idea on the general track area, it is possible that the storm could trend east and completely miss the area, just as much as it could trend west and bring the potential of up to several inches of snow in NYC like the GFS model is showing. Stay tuned for more information on this storm over the next few days.


Longer Range: Cold Pattern Temporarily Breaks Down

After this storm, one thing that is likely is that the cold pattern will break down throughout the week. Temperatures will be steadily warming up as the cold air mass weakens quickly, and by the late week there is the potential for another storm to form, however the models show that storm in the north central US, going along with the idea that the cold pattern temporarily falls apart. With this scenario, we are looking at a storm that could end up well northwest of the area, with warmer temperatures to start the new year and a potential storm for the first several days of the new year that may produce precipitation in the form of rain for the area. Stay tuned for more details on this time frame.