Tropical Mess Moving North

Everything seems on track with a long duration and relatively high impact storm moving up the coast. It seems likely that the heaviest rain and most significant flooding will miss Connecticut. Though total rainfall of 3″-6″ is not out of the question in western Connecticut this will not produce serious flood issues because it’s been so dry lately. That said, urban areas and basements could experience flooding in areas that pick up a large amount of rain in a short period of time (like Danbury this morning).

West of here, across New York and Pennsylvania, rainfall totals of 6″-10″ are possible in some areas which will lead to serious flood problems. In Connecticut, significant river flooding is unlikely.

As for wind potential I think there could be some rather significant wind gusts across the state. A strong low level jet stream (LLJ) is expected to strengthen as the storm moves north. Currently a 60 knot LLJ at 925mb around the Outer Banks is resulting in wind gusts between 50 and 60 mph. The LLJ is expected to increase in strength across Connecticut and Long Island by midnight which will promote damaging wind gusts.

Just because the LLJ is 60 knots doesn’t mean the winds at the ground will be that strong. In fact there is normally a fairly significant reduction in the winds because they mix poorly to the surface, especially in southerly wind events. In fact even though the jet is stronger by the time the storm gets to Connecticut the winds will have a tougher time mixing to the surface so our wind gusts should be comparable to what North Carolina is seeing this morning.

If you look at the forecast from the 6z NAM for 9z Friday morning a 65-70 knot jet is forecast to be along the shore which raises eyebrows, especially this time of year. Because of this, and given the fact the atmosphere looks somewhat unstable, I’m forecasting wind gusts to 60 mph at the shoreline and 45mph inland. This may be enough to bring down some trees and power lines. I’m not expecting widespread coastal flooding because of an unfavorable high tide and the lack of an easterly fetch.

The last issue is the potential for severe weather later today. Very strong shear and some instability could lead to some rotating storms here in the warm sector. The biggest threat may set up west of here across New York and New Jersey but it’s possible scattered storms could cause some problems later today and tonight. Don’t be surprised to see a tornado watch issued later today or tonight.


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