Jan 8, 2011: Another Snowstorm On Wednesday

***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.

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Notes:

- The 5-Day Forecast has been updated for the entire area. In addition, it is possible that snow and heavy snow watches may be issued tomorrow for a snow event that will affect the area on Tuesday night through Wednesday.

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Today, most of the area saw cloudy skies and some light snow as a developing coastal low brought several inches of snow to southern New Jersey. This low is currently bringing light to moderate snow for eastern Long Island and SE Connecticut, where several inches of snow are expected tonight. While conditions will become drier for tomorrow, another storm that will bring a widespread snowstorm to the southern United States will move up the coast to bring another snowstorm for the area between Tuesday afternoon and Wednesday.


Tomorrow's Outlook:

Tomorrow will be a mostly sunny but breezy day across the area, with a WNW wind expected, potentially gusting up to near 30 mph along the immediate coast. High temperatures will be in the upper 20s to lower 30s inland, and in the lower to mid 30s for the rest of the area.

Monday will bring lighter winds for the area with high temperatures again in the upper 20s to mid 30s across the area, though cloud cover will begin to increase overnight as a storm will approach the area from the south.


Tuesday - Wednesday: Another Significant Snowstorm?

For the last few days, there has been a threat for another snowstorm affecting the area. Due to the expected scenario, which will be explained in more details below, it is no longer a question of whether snow falls or not, but rather how much snow falls, therefore I decided to go with 100% of snow for the area. The main uncertainties at this time include whether the area sees any mixing with sleet and rain, whether the storm is too far east to keep most of the heavier snow to the east of NYC, or if the storm takes the middle solution to bring a large snowstorm for NYC and further northeast.


Storm Set Up: A low pressure that is currently in the southern US will move east, bringing a significant winter storm to the southern United States including heavy snow and ice from Sunday night through Monday, with the low pressure ending up near NW Florida around Monday. As the storm moves through Florida and starts going up the coast, a low pressure further inland will become the primary low and will move northeast through the Ohio Valley. With this low pressure to our west and another low pressure to the south, both of them moving northeast, it is a signal that even if the coastal low mainly misses the area, at least some snow should fall over the area.

Around Tuesday into Tuesday night, it appears that the primary low should then weaken with the coastal low becoming the main storm, rapidly intensifying off the coast. Due to this late intensification, the storm's heavier precipitation could miss the southern and potentially central Mid Atlantic, targeting New Jersey/NYC into New England. Once the coastal low becomes the main storm, it will bring heavier precipitation for the area, but whether we see mixing issues or not depends on the primary low. If the primary low stays stronger and lasts longer, the coastal low will likely track closer to the coast, and bring mixing with sleet and rain for the eastern and potentially central parts of the area. If the primary is weaker and the coastal low intensifies further south, then the storm will likely be further east and should be able to keep the central and eastern parts of the area as plain snow. This part of the forecast is still uncertain, and tomorrow we should start to get a better idea on which solution happens.


Thoughts For NYC Area: As I previously mentioned, it is no longer a question of whether snow falls in the area or not, but rather how much snow falls and if we see any mixing with sleet or rain. At this time, I went with a blend in between the eastern and western solutions for the 5-Day Forecast, going with widespread moderate snow in the area and adding the potential of the snow mixing with sleet and/or rain for the eastern parts of the area. Any mixing potential though depends on the storm scenario as I previously discussed, and it is possible that with tomorrow's update, the mixing potential could extend as far west as New York City, or could be removed from the area.

Snow is expected to start in the area around late Tuesday afternoon or the evening hours as the storm comes in from the south. As the coastal low intensifies off the coast, precipitation will also intensify somewhere near or south of the area, with moderate snow likely during the overnight hours on Tuesday. If some model runs such as the 18z DGEX/00z NAM verify, heavy snow could be possible in the central and western parts of the area, though due to uncertainty, I'll wait until tomorrow before deciding whether to include heavy snow in the forecast and if so, then where. Unlike the late December blizzard, however, this storm should move faster and is not expected to stall off the coast, meaning that accumulations will be lower than that storm, and snow will end by the afternoon hours on Wednesday.

Snowfall amounts are uncertain, but at this time the majority of the model guidance shows at least a moderate snow event, with at least a minimum potential near 2 to 4 inches of snow, which would be a more conservative solution at this time. Some models are showing higher snowfall amounts, as much as 10-12 inches of snow in parts of the area, which due to the fast motion of the storm, appears to be close to the maximum accumulations that the area could see. I will go into more details on the potential snowfall accumulations tomorrow and on Monday as details become clearer, but there is the potential for a significant snowstorm with 6 or more inches of snow to affect the area on Tuesday night, with the potential for as much as 8-14 inches of snow. Stay tuned for more information on this storm over the next few days.