Jan 14, 2013: Rain/Snow Weds; Long Range Update

Forecast Highlights:

Temperatures ended up spiking this morning ahead of the cold front, peaking in the low to mid 50s inland and the mid to upper 50s for the rest of the area; parts of Long Island and southern CT reached 60 degrees. A cold front is moving through the region cooling temperatures down while producing rain/sleet, with a storm on Wednesday expected to produce rain for coastal areas and snow inland. The pattern will continue to fluctuate through next weekend, but the peak of winter has yet to arrive in the region as the pattern progressively becomes colder and more active.


Tonight – Wednesday: Rain, Interior Snow Expected

A cold front currently moving through the region will produce rain tonight, with sleet expected further inland. Precipitation will clear the area by Tuesday morning, with mostly cloudy skies on Tuesday with highs peaking in the upper 30s to low 40s inland and low to mid 40s for the rest of the area.

The next widespread storm will affect the region on Wednesday. Initially, this was expected to stay mostly south of the area, but short range corrections on the models are resulting in a widespread storm affecting the region. The model guidance is still inconsistent with the exact impacts, despite the storm only 24-30 hours away from starting; as today’s afternoon update noted, there are two main model solutions at this time, the first with the NAM, CMC and ECM supporting widespread accumulations west and north of NYC, at least 2-3 inches, with some snow in NYC as well. The GFS, SREF and UKMET are further north and warmer, with rain for most of the area with the exception of interior southern CT, far NW NJ and SE NY, where snow falls initially but also changes over to sleet/rain. The models have continuously trended north throughout the day, and the latest model runs coming in as of this evening are continuing this trend.

At this time, I am siding closer to the northern solutions; not as far as the 18z GFS which was the warmest model and currently an outlier, but still north of the southernmost and colder guidance, with some snow/sleet changing over to rain for NYC and Long Island. The north/west suburbs should see more snow/sleet to start before changing over to rain, with minor accumulations likely. More snow is expected further inland, towards NW NJ, SE NY and southern CT, which will also mix with sleet and some rain as the storm ends. Should this scenario verify, at least 1/2 to 3/4 inch of rain is likely for NYC and further east/south, with at least 1 to 3 inches of snow/sleet for the northern parts of the area. There is still some uncertainty given the model differences, however, and it is still possible that the southern solutions would be closer to verifying, in which case higher accumulations would take place in northern NJ and southern CT, with some more snow in NYC and northern Long Island as well. Stay tuned for another update on Tuesday morning regarding this storm.

Thursday – Friday: Briefly Cooler; Mid Atlantic Storm Possible

Temperatures are likely to warm up again on Thursday into the upper 30s to mid 40s ahead of an arctic front approaching the Northeast, with the polar vortex dropping into southeastern Canada. At the same time, a strong shortwave in the southern US will move northeast, towards the Mid Atlantic, although there is not much amplification in the flow, and while the model guidance will likely continue to fluctuate with the track of this storm, perhaps ending up north of the latest outlooks keeping the impact limited to southern Virginia and North Carolina, the storm is still expected to remain mostly, if not entirely south of the area.

Temperatures will briefly get cold for the area on Thursday night and Friday, with lows in the 20s for most of the area and the 10s for interior locations, with highs on Friday in the mid to upper 30s for most of the area. Even with the colder air mass, these temperatures are still not far from average.

Next Weekend – Beyond: Warmer, Then Much Colder

A weak low pressure is expected to track through the northern Northeast, which will bring a warmer air mass into the region with 850mb temperatures likely rising above zero degrees Celsius. As a result, temperatures will be warmer for the weekend again, reaching the 40s across most of the region. As the recent pattern outlook mentioned, however, this mild period that will leave the first 20 days of January much warmer than average will not last for long. A more displaced polar vortex is expected near southern Canada, which along with ridging in the western US and minor ridging near Greenland, will result in a colder pattern developing for the region starting about early to mid next week. Some models have been hinting at a potential storm on the 22-24th; while this is still too far out to know exactly what will happen, the pattern appears to be generally dry at first, with the potential for for Alberta clipper-like systems to affect the region at times with light snow, with the pattern potentially trending wetter and possibly snowier later on into the end of the month and February. Stay tuned for more information on the longer range pattern with the next pattern outlook later this week.

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