Warmup begins, brings unsettled weather

After a powerful Nor’Easter which featured a minimum central pressure of 955mb and wind gusts over 80mph on Nantucket, cold air swept back into the area late Wednesday into Thursday. Wind gusts in our area were more modest, but still over 30 mph in many spots. The cold airmass which moved into the area helped us set records of our own on Thursday morning. LaGuardia, Newark and Kennedy airports all set record low temperatures for the day, breaking records which were set during a similar cold snap in 2001. The departure from normal temperature remained more impressive than the actual surface temperatures, which actually only fell into the low 20’s. Normal lows this time of year, however, are in the mid to upper 30’s.

Fortunately, the colder than normal airmass will fall victim to a very progressive pattern, and is already on its way out. Temperatures on Thursday afternoon will rise into the 40’s to near 50 in many areas, under full sunshine and warming temperatures aloft. A continued warmup is expected from Saturday through the early part of next week. However, with the warmth will come southerly winds, increased moisture and a few low pressure systems which will do their part to provide the area with unsettled weather and multiple chances for rain.

GFS model showing a parade of systems moving eastward from the Pacific into the United States.

GFS model showing a parade of systems moving eastward from the Pacific into the United States.

The first will come on Friday as a weak low pressure system passes the area and vorticity aloft traverses through New England. This will drag a weak cold front through the area Friday afternoon and evening. Forecast models indicate sufficient lift for an area of precipitation to move through Pennsylvania, New Jersey, New York and Connecticut. Although temperatures won’t drop much behind the front, the clouds and showers will put a damper on what otherwise would’ve been a pleasantly warm Friday.

After some drying behind the front leaves us with a brief period of pleasant weather early on Saturday, things will take a turn for the worse once again. A stronger upper level system is forecast by model guidance to move from the Ohio Valley to a position off the Mid Atlantic coast late Saturday through Sunday. The closed upper level low will bring more moisture and lift for precipitation with it, and so periods of rain are expected through Sunday.

NAM model forecasting a period of very heavy rain throughout the area late Saturday Night into Sunday.

NAM model forecasting a period of very heavy rain throughout the area late Saturday Night into Sunday.

Models indicate the potential for a period of heavy rain Saturday Night through Sunday, moving from southwest to northeast through the area. As a developing surface low moves through the Mid Atlantic states, into New Jersey and eventually off the coast, increased lift/ascent will allow for heavier precipitation to develop within an axis of moisture. So while showers and clouds are likely a few times this weekend, we are confidently pinpointing this time period for a steadier and heavier rain. The low pressure system eventually shifts northeast, but low level moisture may linger into Sunday.

The good news, from the “It could be worse” department? The only thing waiting behind this storm system during the early part of next week is a mid level ridge axis. However transient it may be, mid level temperatures and clearing skies on Monday and potentially Tuesday as well look favorable to support temperatures much more reasonable for this time of year — in the 50’s and potentially even 60’s.

Let’s get through this slightly warmer, unsettled period first and then we can potentially start talking about above normal temperatures.

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