1/23 AM Coastal Zones Update for High Winds and Coastal Flooding

East to northeast winds this morning have already gusted up to 45 to 50 mph parts of the region, as a significant Nor’easter begins to take shape to our south. These winds also have already lead to some minor coastal flooding at high tides around the region this morning. High wind warnings and coastal flood warnings have been issued by National Weather Service for even stronger winds and more coastal flooding for this afternoon and evening.

A stronger low-level jet with winds near 65 to 70kt around 925mb and 950mb (a few thousand feet above our heads) will be moving through region late this afternoon and evening. Recent model soundings show a more unstable, moist-mixed layer underneath a mid-level inversion. Overall, this results in larger portion of these 50-55kt winds being mixed down from the 925mb to 950mb level this afternoon.

This will likely lead to wind gusts over coastal locations between 45-55mph this afternoon. Enhanced friction convergence may support gusts between 55mph to 65mph gusts right near the shores. These winds could bring down tree branches and power lines. Even higher winds to near hurricane force or up to 80mph are possible in the ocean waters offshore.

12z 4km NAM showing 63kt winds on top of a MAUL near 900mb, over Atlantic Highlands, New Jersey at late this afternoon

12z 4km NAM showing 63kt winds on top of a very moist unstable layer between 900mb and 975mb, over Atlantic Highlands, New Jersey at late this afternoon

Later this evening, the core of 70kt jet passes coastal zones. But the NAM model indicates lower mixing heights and weakening lapse rates early this evening. So there may be a lull with the winds this evening, before they pick up again later this evening and overnight as heavier rainfall moves through region. Later this evening, the core of 70kt low level jet passes coastal zones.

The stronger winds this afternoon may coincide with high tides from about 4 to 7pm today. If this occurs, more moderate coastal flooding is likely along the south shore of Long Island, the Western Long Island Sound, and along the New Jersey shore. Areas most prone appear to be around the back bays between Freeport and Lindenhurst in Long Island. At least moderate flooding is forecast with tides more than 3 to 4 feet above normal. But ensemble spread indicates some locally major flooding is possible here. Heavy rainfall this evening may also exacerbate flooding in these areas.

Flood guidance Lindenhurst reaching minor flood stage this morning, and forecast to reach at least moderate flooding leave during high tide early this evening

 Flood guidance from Steven’s Institute around the Great South Bay at Lindenhurst, which is was near or slight above flood stage early this morning. Now  forecast to reach at least moderate flooding leave during high tide late this afternoon and early this evening

If winds are weaker during the high tides, coastal flooding may not reach the higher end of guidance. We are also in an astronomical normal tide period, between quarter moon and new moon phase. So this will likely prevent more significant, widespread coastal flooding.

Low pressure slows down and occludes just off the New Jersey on Tuesday. This will cause a strong northeast flow to persist for another at least minor coastal flooding during the Tuesday morning high tide cycle. Stay tuned for more updates this afternoon or this evening, if necessary.