Heavy rains and Thunder Possible Overnight Wednesday into Thursday

For several days now computer forecast guidance has been extremely consistent with the potential for a rather strong and intense storm system, however, the consensus with regards to the track of the storm was up in the air.  Over the past few days a consensus has been drawn that the system will indeed pass well to our west.  With a track so far to the west we will not see snow (perhaps early AM Wednesday we would see some frozen precipitation with the first part of the storm), however, we will be dealing with the potential for some extremely heavy rainfall and even the potential for some thunderstorms. 

The graphic below is from today's (2/21) run of the GFS computer forecast model looking at the 500mb heights/winds.  What we see here is a very deep trough pushing towards the east coast of the United States associated with very intense winds at the 500mb level forecasted to be as strong as 110-120+ knots (indicated by the purple colors).  Notice at this time how the core of these winds are just to the southwest of southern New England.  This will place the region in a very favorable position for very strong and rather intense lifting which will enhance the potential for heavy rains as well as the potential for thunderstorms.   

The GFS forecast model is indicating some anomalously high precipitable water values pushing into southern New England overnight Wednesday with values as high as 1.3'', an indication that some areas could receive at least 1'' of rainfall!

Another interesting aspect of this system is the forecasted instability right now.  The GFS right now is advertising a decent surge of elevated instability (instability which occurs above the boundary layer) moving into the region overnight.  This perhaps occurs due to steepening lapse rates in the mid-levels of the atmosphere coincident with decreasing temperatures aloft while temperatures in the lower levels and the surface increase (along with moisture content):

Forecasted lapse rates overnight Wednesday into Thursday:

Forecasted MUcape overnight Wednesday into Thursday:

All in all for snow lovers this system is bad news, however, for any weather enthusiasts this will be a fun system to watch given the dynamics involved.  We will see some pretty heavy rains push through the region along with the potential for thunderstorms and strong winds.  More to come as the week progresses!