Visible satellite imagery on Tuesday morning showing clouds from the onshore flow and developing coastal storm.

Morning roundup: Unsettled, coastal storm slips by

Temperatures in the 50’s and 60’s made this Tuesday morning feel extra Autumn-like, despite easterly winds and an onshore flow. Clouds were more prevalent over southern/eastern areas of New Jersey and Long Island. The marine air will continue pushing westward today, and the gusty winds and higher surf will return to the area shores once again. The clouds and showers won’t necessarily be widespread, but they’ll certainly put a bit of a damper on the day.

A developing coastal storm, owing to a mid level disturbance passing near the East Coast, will bring a period of rain very close to the New Jersey and Long Island coasts on Tuesday morning and afternoon. But westerly winds pressing on the system aloft will keep the precipitation from spreading inland. Instead, breaks in the clouds will be just as common as scattered showers throughout the area — and so while Tuesday won’t be sunny and bright, it won’t necessarily be a washout either.

As mentioned yesterday, the mid and late week weather story becomes changing winds and the approach of a major cold front. A significant system will move through the Central United States during the mid part of this week, bringing the potential for severe weather in the North-Central United States and parts of the Great Lakes. The significant cold front associated with the large mid and upper level trough will eventually shift eastward toward the Northeast US.

GFS model showing a significant system moving into Canada, bringing a strong cold front through our area.

GFS model showing a significant system moving into Canada, bringing a strong cold front through our area.

The thermal boundary and forcing aloft will lead to the development of showers and thunderstorms throughout the Northeast US on Friday. While the extent of the severe thunderstorm threat remains uncertain, at least scattered thunderstorms with the potential to be strong/severe appears likely. The Storm Prediction Center has placed our area in a 5% risk for severe thunderstorms. Their discussion highlights the uncertainties regarding the severe weather potential:

STRONGER MID/UPPER FORCING FOR ASCENT IS EXPECTED TO
   SHIFT NORTHEASTWARD THROUGH QUEBEC DURING THE DAY.  HOWEVER...
   DESTABILIZATION BENEATH RESIDUAL WEAK TO MODEST...BUT
   CYCLONIC...MID-LEVEL FLOW MAY BE SUFFICIENT TO SUPPORT VIGOROUS
   PRE-FRONTAL STORM DEVELOPMENT ACROSS THE ALLEGHENY MOUNTAINS.  IT
   APPEARS AT LEAST POSSIBLE...GIVEN THE BOUNDARY LAYER MOISTENING AND
   HEATING EXPECTED TO THE EAST OF THE HIGHER TERRAIN...THAT ACTIVITY
   COULD ORGANIZE SUFFICIENTLY TO SUPPORT THE RISK FOR POTENTIALLY
   DAMAGING WIND GUSTS AS IT SPREADS TOWARD THE MID ATLANTIC COAST LATE
   THURSDAY AFTERNOON AND EVENING.

The eventual amount of destabilization that occurs in the atmosphere to support storms will depend on exact details, such as cloud cover and wind direction as well as marine influence near the coast. These details, unfortunately, won’t become more clear until much later this week.

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