Jan 27, 2013: Snow/Ice Tomorrow, Then T-Storms/Wind

Forecast Highlights:

Today was the last day of the  cold spell across the region with highs the warmest they have been in a week, peaking in the low to mid 30s across the area, the first time since last Monday that temperatures reached 32 degrees in Central Park. A rather active setup is unfolding for this week, starting out with light snow, sleet and freezing rain on Monday, mostly west and north of NYC, eventually ending up with nearly 60 degrees on Wednesday with heavy rain, thunderstorms and strong winds.

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Tonight - Monday: Light Snow, Sleet, Freezing Rain

As shown in the Great Lakes region radar to the left from the NWS, widespread precipitation is currently being observed in the Great Lakes region, where light to moderate snow and freezing rain fell earlier today. This system will continue to advance east into the region, producing a widespread wintry mix on Monday.

Light snow is expected to develop across the area on Monday morning, towards 8-11 AM from west to east. Mid level temperatures will be quick to warm up above freezing, but surface temperatures will take longer to do so, resulting in a freezing rain scenario for some. Towards approximately 12-4 PM, snow will change over to sleet and freezing rain from west to east; towards NYC, Long Island and the immediate north/west suburbs of NYC, there should be a period of sleet initially followed by a changeover to rain by the evening. Further inland, light freezing rain or drizzle is expected to linger through the evening hours, before changing to plain rain later overnight as well with surface temperatures warming up to near and above freezing.

There are two maximums of snow accumulations in the region; the first over Pennsylvania with some areas likely seeing 1-2 inch accumulations, with the precipitation likely weakening as it reaches the area but still capable of producing over 1/2 inch of snow north and west of NYC, perhaps exceeding an inch for interior areas. The second maximum of snow accumulations will remain well north of the area, towards far northern NY state into New Hampshire and Vermont. There is still some uncertainty where exactly the higher totals in Pennsylvania and potential local minimum over NY state set up, and these areas on the map could be slightly revised with short term observations/forecasting tomorrow.

Some freezing rain is expected north and west of NYC as well, with up to 0.10 inch likely; while this will not be a major ice storm, the light intensity of the freezing rain is a concern as it will be able to freeze onto surfaces easier than heavy freezing rain would, resulting in hazardous conditions for interior parts of the area towards the afternoon and evening hours. Updates to this map will be posted on Monday morning.

Storm updates will be posted throughout the day on Monday. With the focus on tomorrow's wintry mix, the February long range outlook has been delayed into tomorrow evening or Tuesday morning, after the wintry part of the event is over.


Tuesday - Wednesday Night: Heavy Rain, Strong Winds, Thunderstorms

While the area will be affected by wintry precipitation, a strong low pressure will develop in the north central US, moving towards the Great Lakes region and into Canada as a strong cold front makes its way towards the region. A strong warm air mass will move into the region, with a widespread severe weather outbreak expected from this cold front as far north as the Ohio Valley and Mid Atlantic regions, reflecting a drastic change within two days from cold and snow/ice to unseasonable warmth and thunderstorms.

Tuesday will remain mostly cloudy across the area with scattered showers; there remains uncertainty regarding the high temperatures, with some models suggesting highs in the low to mid 50s while others struggle to bring temperatures above 40 degrees. At this time, I am siding in between with highs generally in the mid to upper 40s across the area, perhaps approaching 50 degrees near NYC, with this outlook subject to some revisions.

By Wednesday, the strong cold front will enter the region, with thunderstorms, potentially strong to severe, likely over the southern-central Mid Atlantic states and potentially extending into Pennsylvania. Mostly cloudy skies are expected for the area with stronger winds out of the SSW, with highs likely reaching the mid to upper 50s from NYC and further west/southwest, and the low to mid 50s north and east of NYC. By the evening through the early overnight hours, the cold front will move through the area, producing heavy rain with up to 1 inch possible in a few hours, thunderstorms for parts of the area, and strong wind gusts. A strong low level jet is expected with 925mb winds up to 70-90 knots, especially over the eastern parts of the area; most of the area is expected to see wind gusts in the 45-55 mph range, with parts of Long Island and eastern Connecticut possibly exceeding 50-55 mph gusts. Stay tuned for more information on this heavy rain, wind and thunderstorm event.


Longer Range: Colder Again, Light Snow Possible

Behind the cold front, a colder air mass will return as strong cold air drops into the north central US; the coldest temperatures, however, will remain well west of the area, although temperatures will still end up colder than average, with lows in the 10s and highs in the 20s and 30s. The pattern will remain generally dry, with a few weak low pressures possible during this time period into next weekend and the following weak producing light snow in parts of the region.