Threat of coastal storm increasing for Thanksgiving weekend

500 MB pattern on Thanksgiving-NWS/NOAA

A strong trough that will carve into the eastern United States will lead towards a very active period for Thanksgiving for much of the Mid Atlantic and especially over New Jersey.

On Wednesday, a cold front will slowly move through New Jersey with scattered showers.  Stronger lifting will be focused towards northwestern New Jersey where heavier showers can be expected on Wednesday afternoon.  This cold front will move off the New Jersey coast by Wednesday evening and set the stage for what will be a potentially stormy end to Thanksgiving and for Black Friday.

A strong disturbance will dive into the base of the trough on Thanksgiving, sparking the development of a coastal low off the North Carolina coast.  Meanwhile, dry conditions can be expected on Thanksgiving morning with light winds over much of New Jersey, which will lead to perfect driving conditions in the morning.  As the day progresses, clouds will increase as the coastal low develops off the North Carolina/Virginia coast.  The low will continue to intensify on Thursday afternoon as showers increase from southern New Jersey into central New Jersey on Thanksgiving evening.

On Thanksgiving night into Friday, the coastal low will move into the New Jersey coastal waters and intensify significantly.  There is strong agreement in the model guidance that the trough will tilt to a negative axis, which will cause the coastal low to slow down and intensify significantly.  The pressure of the low from Thursday evening will drop from 1008 MB to 994MB by Friday morning.  As the low intensifies, cold air will rush towards the coast dropping temperatures at most levels of the atmosphere below freezing.  Moisture will be forced into the New Jersey coast from the Atlantic, with moderate to heavy precipitation throughout New Jersey, but especially over the New Jersey coast.

The tricky part of the forecast is how to handle cold air advection on Friday morning.  While the mid levels of the atmosphere will be more than cold enough to support snowfall throughout much of western and northern New Jersey and even towards the coast by the afternoon, the lower levels of the atmosphere are going to be harder to cool.  I expect rain to be heavy at times along the coast with a slow mix of snow and sleet as the afternoon progresses.  No accumulation can be expected in these locations.  However, over the interior locations of northwestern New Jersey, locations in the higher elevations will have a higher threat for the rain to change over to snow and accumulation is possible on Friday morning and continuing on through Friday afternoon.  Regardless, travel conditions late Thursday night through Friday will be hampered by this storm with strong winds from the northeast and heavy precipitation.  Visibility will be reduced significantly as a result.

I will follow the development of this storm through the week.

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