The most significant snowstorm of the winter affected the region yesterday, producing widespread heavy snow, accompanied by rain, sleet and thunderstorms, with snow totals between 10-20 inches bringing this winter’s snow to well above average, and in Central Park the 9th snowiest winter on record. The pattern does not offer a break from a snow just yet, however, as yet another strong nor’easter rapidly develops off the coast tomorrow, with widespread moderate snow likely in the area tomorrow developing into a blizzard in eastern New England.
Tomorrow’s Outlook: More Snow
The forecast for tomorrow has been the subject of the latest in a series of significant short range trends in the model guidance this winter, which has already occurred multiple times over the last month including January 21 and February 3. A strong shortwave trough is currently present over Arkansas, and is diving southeast while amplifying and gaining a neutral and later negative tilt. Earlier model runs kept this shortwave flatter and gaining a negative tilt too late and too far east, leading to only light snow showers staying well to the south and east. Partially due to the models incorrectly handling the kicker shortwave which a few days ago was modeled to help keep yesterday’s storm from lasting too long but ended up having more interaction with the closed upper level low, height rises ahead of the current central US shortwave are notably more amplified than modeled a few days ago, leading to a stronger and sharper shortwave trough that digs further south and becomes negatively tilted at a favorable position to result in a rapidly deepening nor’easter tracking parallel to the coast, the second such storm to do so in only three days.
The GFS was among the first to significantly trend stronger and west with the low pressure over the last 2-3 days, as it has also done with the January 21 storm when it was among the first models to fully catch onto the potential magnitude of the storm. The remainder of the model guidance has been slower with this trend but has also continuously trended towards a further west low pressure. The model guidance is in general agreement of over 6-12 inches of snow from eastern Massachusetts into Maine, with over 18-24 inches of snow possible in Maine, along with blizzard conditions due to the tightening pressure gradient associated with the rapidly deepening low pressure, but with uncertainty regarding the impacts further west. The GFS is the westernmost model at this time, with at least a 3-6 inch snowfall for most of the area and heavier precipitation over Long Island/SE CT, with the potential for over 6 inches of snow, but with some mixing with rain as well. The remainder of the models are generally drier with at least 2-4 inches of snow, over 4 inches in Long Island/SE CT. Widespread moderate snow of near 2-5 inches is expected to spread through Pennsylvania, but with the potential for lower snow totals in the immediate NYC area as the low transfers to the coast and the best dynamics develop east of NYC, as sometimes occurs during similar storm setups. The main uncertainty is how far west the heavy banding expands; if it ends up further west than currently indicated, snow totals over 4-6 inches would extend into western Long Island and NYC.
Forecast for NYC Area: At this time, the outlook is for snow to develop in the mid-late morning, continuing through the evening before ending after at least 7-10pm, perhaps persisting longer over parts of Long Island/CT up to 12-1am. Snow totals up to 2-5 inches are likely for most of the area, possibly a bit lower near the immediate NYC area, and 4-8 inches in most of Long Island and CT with the possibility of rain mixing with the snow at times in coastal Long Island. Given the strong dynamics anticipated, heavy snow banding may develop over Long Island and CT, with the possibility for snow totals as high as 8-12 inches of snow not out of the question. There remain some uncertainties as the model guidance continues to display a lack of agreement, despite the event only 12 hours away from starting, and the outlook is subject to some changes tomorrow morning. Occasional storm updates will be posted during the day tomorrow.