April 24, 2012 Brief Update

Forecast Overview:

Wednesday – Thursday: Partly to mostly cloudy skies are expected tomorrow with a risk of isolated showers. Temperatures will reach the mid 50s to lower 60s on Wednesday. A low pressure will move through the region on Thursday, resulting in cloudy skies and occasional showers with at least 1/4 inch expected. Temperatures are expected to reach the mid to upper 50s further east and the upper 50s to lower 60s from NYC and further west.

Friday – Weekend: As the low pressure moves into southeastern Canada while intensifying, a cold air mass from northern Canada will drop into the region, once again keeping temperatures cooler than average. Mostly sunny skies are expected on Friday with highs reaching the mid to upper 50s across the area, possibly getting near 60 degrees in the immediate NYC area. Clouds will begin to increase overnight and into Saturday, with highs on Saturday reaching the lower to mid 50s across most of the area, possibly getting into the upper 50s near NYC if there’s enough sunshine.

A wave of low pressure will approach the region on Saturday. With the low in SE Canada, any approaching storm will not be able to track well to the north of the area, with the main favored tracks at this time either not too far to the south of the area, resulting in rain, or far enough to the south so that it does not rain, although most models currently point to the rain outcome. Especially given how the models overestimated suppression with this pattern in some cases, including March 31 which was the last snow event close to the area, I am currently siding with the northern outcomes. While some rain may fall during the day on Saturday, especially if the wave ends up faster than expected, most of the rain potential appears to focus on Saturday night into Sunday.

With the track likely south of the area, along with a relatively strong cool air mass in the region, snow may come into play once again for parts of the region. The GFS and DGEX currently show snow falling in northern Pennsylvania, while I am considering the 12z ECM as an outlier for showing snow as far south as NYC. The time of the year alone strongly argues against snow reaching NYC, with many parts of the storm required to end up in the right place for it to actually snow in the city, although there is a possibility that if there is enough cold air and precipitation, snow may fall in parts of Pennsylvania/New York state. Regardless of whether snow reaches the higher elevations of NW NJ or not, this appears to be a cold storm, with temperatures struggling to get out of the 40s for highs should the timing and location of the storm support rain during the day. Dry conditions will return for early next week with warming temperatures. Stay tuned for more information on next weekend’s outlook.

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