Already Raining in Eastern MA

It won't rain in Eastern MA until this afternoon (Me-yesterday).  Opps.  Well I blew that one.  Pouring in Middlesex, Suffolk,  and Essex counties.

NWS Northeast Regional Radar Loop

The combo surface and water vapor satellite shows the front and upper level low in the Northwest Atlantic nicely.  The low is undoubtably helping to feed moisture northward into Southeastern New England as it interacts with the cold front.

GOES_East Water Vapor, Surface 745 AM

Here is the 500 mb chart from 2 AM morning.  The upper level flow is into Quebec and North of Atlantic Canada.  Yet there is convergence from the interaction of the upper level features.  That puts New England in a favorable spot for heavy rain and thunderstorms today.  I should have seen this yesterday.

6z NAM 500 mb vort 2 am (mage NCEP)

That said the convergence at the upper levels should subside this afternoon, but a tropical air mass remains in place so thunderstorms capable of flash flooding and lots of lightning will be a threat all day.  The short range high resolution guidance suggests Eastern MA is under the gun for storms until later this afternoon before the bulk of the storms shift to Northern New England.  For example here is the simulated 8 PM radar.

11z HRRR simulated radar 8 PM (image NCEP)

WPC 1-3 day total rainfall forecast

Over the next 3 days the WPC thinks 1-2" of rain is likely
There will be more rain in areas where thunderstorms develop today.  There is a lot of moisture in the atmosphere.   Saturday looks to feature widely scattered showers and thunderstorms. 

-Zack Green