Mar 15, 2013: Cold, Stormy Pattern; Snowy For Some

Forecast Highlights:

Starting on Wednesday night, a strong trough moved into the region, marking the beginning of a winter-like pattern in spring, with temperatures generally near to below average persisting through the end of the month and potentially into April. With the pattern in place, additional storminess is expected, including Tuesday and potentially next weekend, and the region will see more snowstorms before the winter ends, potentially in the NYC area as well.

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Thursday, 3/14 Observations:

A cold air mass moved into the region on Thursday, bringing an end to the temporary warm-up as a cold pattern began to develop. Temperatures were colder than average across the entire area, in some cases 10 degrees colder than average, with highs peaking in the low 40s in NYC and northern NJ and the upper 30s for the rest of the area. Central Park peaked at 41 degrees, 8 degrees colder than the average high of 49. Breezy NW winds of 15-30 mph were observed, with gusts up to 30-40 mph.


Friday, 3/15 Observations:

The cold air mass from Thursday night moderated slightly on Friday with slightly warmer temperatures but still remaining slightly colder than average for most. Highs peaked in the low to mid 40s in the northern half of the area and eastern Long Island, and the mid to upper 40s for the southern half of the area. A breezy W to NW wind was observed, with gusts up to 20-30 mph.

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Tonight - Monday: Light Snow Showers, Still Cold

The first system to affect the region since the development of the cold pattern will be on Saturday into Saturday evening. A broad area of light precipitation over the Midwest will spread ESE tonight into Saturday as a weak low pressure develops near the Ohio Valley and tracks into the region. Widespread snow showers are expected over Pennsylvania by Saturday morning into the early afternoon hours, with light accumulations likely for parts of the state. Most models show at least light precipitation making it into the area, which with temperatures cold enough is likely to support snow or a mix across the area despite the timing of precipitation during the afternoon and evening. Precipitation is expected to dry up as it reaches the area, although the main question at this time is how much precipitation makes it into the area. Most models agree with near or under 0.10" of precipitation, which will likely fail to accumulate to much, if anything for most locations, especially when taking light precipitation rates and the higher March sun angle into consideration.

The current outlook is for mainly cloudy skies on Saturday along with scattered snow showers, mixing with rain further east, and perhaps with a steady period of light snow in western parts of the area. High temperatures will remain colder than average, peaking in the mid to upper 30s inland and the upper 30s to low 40s across the rest of the area. Clearing skies are expected overnight with another round of cold temperatures, dropping into the 20s across the area, with mostly sunny skies on Sunday and highs in the upper 30s inland and low 40s across the rest of the area.


Monday Evening - Tuesday: Storm Produces Rain, Some Snow

While the area is expected to see scattered snow showers on Saturday, another storm will enter the northwestern US, continuing the active cold and stormy pattern in place. This low pressure will continue to track east through the northern US, tracking towards the northern Great Lakes as a secondary low pressure develops further south, likely near the area, which then intensifies as it continues northeast into New England. With enough cold air in place, this is likely to result in a widespread snowstorm in the interior Northeast region. The area is more borderline, as temperatures initially look cold enough to support snow in the evening hours, but then warm up enough to support a changeover to rain across the whole area as the secondary low develops nearby. Rain is expected to continue falling later overnight into Tuesday morning, possibly heavy at times, with drier conditions likely for the rest of the day as the secondary low reaches New England and another cold air mass drops into the region.

Based on the current expectations, a widespread snowstorm is likely in the Northeast region, with at least some snow in the area before the changeover to rain. How much snow falls is uncertain at this time, with possibilities ranging from light snow showers quickly changing over to rain, to a longer period of moderate snow in the evening to early overnight hours which then change over to rain but not before producing accumulations north and west of NYC. At this time, I am siding towards the potential for light accumulations for interior parts of the area, although this is still subject to some changes. Stay tuned for more information on this storm.


Longer Range: Pattern Continues, Friday-Weekend Storm Possible

During this time of the year in 2012, a massive ridge sat on top of the region. After what was already an unusually mild winter, summer-like warmth was observed for a full week, with many record highs shattered across the region as temperatures climbed into the 70s for the NYC area and 80s in New England. This year is nearly the complete opposite; a significant blocking pattern continues with temperatures generally colder than average across the region, with no break from this pattern in sight until at least the end of the month into early April. This will keep temperatures mostly chilly through the rest of the month with additional storms expected, which given the pattern in place are likely to support additional snow potentials across the Northeast and perhaps for the NYC area as well.

Cold temperatures are expected again for Wednesday and Thursday, likely in the upper 30s-mid 40s range for highs again with lows in the 20s. The next storm potential is expected towards Friday and possibly Saturday. With an upper level low likely over the Northeast and Atlantic Canada following the midweek storm, should a storm take place during Friday and Saturday, it is likely to end up south of that storm. Most of the medium range models are split between either a southern track with no precipitation for the area, or a further north track in which the storm is far north enough to support a snowstorm for the region including the area. This storm is nearly a week away, and it is still possible there may not be a storm in this time frame, but it will continue to be watched for the possibility of impacts in the area, including the possibility of snow. Stay tuned for more information on the longer range pattern and storm potentials over the next few days.