Dec 27, 2011: Cold Returns Tomorrow

The squall line has moved through NYC, with places from NYC and further west drying up as the storm moves to the east. Strong wind gusts were observed across the area with the squall line, with wind gusts reaching 48 mph in LaGuardia and JFK so far. Reports of higher wind gusts over 50 mph are likely to come in likely in Long Island and southern CT within the next hour. Temperatures steadily warmed up ahead of the squall line and ended up slightly warmer than expected, with the high temperature peaking late this evening in the lower to mid 50s inland and the mid to upper 50s across the rest of the area.

Skies will clear tomorrow with much colder temperatures, especially for the overnight hours into Tuesday, along with gusty winds throughout the day on Wednesday. The return of colder temperatures will be brief as a clipper moves into the region, bringing light rain showers, possibly mixing with light snow north and west of NYC on Saturday, ending just in time for New Year’s Eve. The start of the new year could perhaps bring new opportunities for storms, however, as there are more signs for a potentially stronger storm affecting the region around the start of January.

Tomorrow’s Outlook:

A high pressure moving towards the region will bring clearing skies across the area. As a much colder air mass will move into the area throughout the day, temperatures will be steady in the morning to the early afternoon hours in the upper 30s inland and the lower 40s across the area, starting to drop for the rest of the afternoon hours into the 30s. A breezy west wind is expected, gusting up to 30-40 mph across the area.

Much colder temperatures are expected for tomorrow night as skies clear, winds diminish and radiational cooling takes place. Temperatures are expected to drop into the lower to mid 10s inland, mid 10s to lower 20s in the north/west suburbs of NYC and southern CT, upper 10s to mid 20s in Long Island, and the mid to upper 20s in NYC. The eastern parts of Long Island that typically see colder temperatures with radiational cooling are likely to drop into at least the mid 10s. With breezy winds especially in the evening, wind chills will fall below 20 degrees across the entire area.

Thursday – Sunday: Clipper Brings Light Rain/Snow For Fri/Sat

With the high pressure over the region, mostly sunny skies are expected again for Thursday with colder temperatures, peaking in the mid 30s inland and the mid to upper 30s across the rest of the area, reaching 40 degrees in parts of the immediate NYC area and Long Island. As a weak clipper moves towards the region from the Great Lakes, however, clouds will increase on Thursday night as isolated showers approach from the west. Most of the precipitation from the clipper will stay to the north of the area on Friday and Saturday, keeping the best chance for snow once again to the north of the area, across the Northeast, while temperatures aloft stay mostly above freezing across the area.

On Friday and Friday night, mostly cloudy skies are expected with high temperatures reaching the mid 40s across most of the area with mid to upper 40s in the immediate NYC area. Any precipitation that falls will most likely be in the form of rain in the immediate NYC area and Long Island, possibly mixing with snow showers in interior southern Connecticut and NW NJ/Orange County in NY. As colder temperatures move in, light snow showers may mix in as far southeast as the north/west suburbs of NYC on Saturday morning before the clipper moves out of the region, bringing high temperatures into the mid 40s to lower 50s on Saturday afternoon along with partly cloudy skies in time for New Year’s Eve and temperatures in the mid 30s to start out the new year. Not so surprisingly, above average temperatures will continue into the first day of 2012, with high temperatures reaching the mid to upper 40s across the area, possibly reaching 50 degrees again in NYC.

Next Week: Storm And Cold Possible?

Differences with the models significantly increase by early next week. The models are in agreement with showing a low pressure moving towards the Great Lakes region on Monday, but significantly differ with details afterwards. The GFS model brings the low pressure through Maine before bringing a very strong cold air mass into the region, with high temperatures only near 20-25 degrees in NYC. The CMC brings a stronger cold front through, with the last frame of the 12z CMC, at Tuesday night, showing a developing coastal low with snow across parts of the area and more snow approaching from the south. The most interesting model of the day, however, was the ECMWF, showing a major snowstorm for the region with both of its runs today. The morning run of the ECM showed heavy rain for the area, but with heavy snow falling not too far west, from Virginia into Pennsylvania and New York. The 12z run showed another strong storm but further east, bringing a significant snowstorm for a large part of the NYC area.

Although the models are showing different solutions, most of the models do show more amplification in the set up across the US than what we have recently seen, with a stronger ridge in the western US and a stronger trough in the eastern US, perhaps the strongest trough the region has seen so far this winter. Although the pattern remains mostly unfavorable, transient features in the pattern such as a temporary western US ridge do show that the potential for a more significant storm, although still low, is in fact there. Although the GFS model may be correct with not showing a coastal low, it is most likely too strong with the intensity of the cold spell that it shows, and is expected to change its solution over the next 1-2 days. The ECM is most likely too amplified, showing a nearly ideal scenario needed to produce a snowstorm for the area, but while the storm may not be as strong as it shows, both the ECM and the CMC show that there is at least the potential for a storm to affect the area, although the timing, location and intensity remain uncertain. The GFS and CMC ensembles show no storm for Tuesday into Wednesday, however, and although less amplification should be expected with ensemble means this far out, the 12z ECM ensemble mean does not show any storm affecting the area on Wednesday, unlike the operational ECM run which shows the storm.

Although there is the potential for a more significant storm around early-mid next week, this potential is uncertain, and especially given the pattern in place, is still low at this time, although this is still subject to change. Regardless of whether a storm affects the region or not, however, a trough is likely to move into the region around early-mid week, bringing much colder temperatures, possibly the coldest the area has seen so far this winter if the trough ends up amplified as currently modeled. Stay tuned for more information on the longer range outlook throughout the next several days.

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