Showers/T'storms Across New England Tuesday, June 7th, 2016

A trough is expected to dig and amplify through the Great Lakes region and push towards the New England states during the day on Tuesday.  Associated with the amplifying trough will be a strong cold front sliding east along with a rather potent piece of shortwave energy which will move through the middle levels of the atmosphere.  As this potent piece of shortwave energy approaches it will be accompanied by some rather anomalous cold air in the mid-levels of the atmosphere (500mb temperatures...~18,000ft ASL about -14C to -17C!!!).  As the system approaches we may see conditions in place which will favor the development of showers and thunderstorms and some of these storms could be strong to severe:

Tomorrow's setup is quite intriguing across New England as the anomalous mid-level cold temperatures will provide some very steep mid-level lapse rates across the region (meaning a quick decrease of temperature with height through the troposphere) on the order of 6.5 C/KM to 7 C/KM.  While there will be some cloud cover and perhaps some AM showers or even a thunderstorm to deal with, there is a possibility that we break through the clouds as the morning progresses, allowing for sunshine and ample heating to occur.  If enough sunshine breaks out some areas could see high temperatures push into the lower 80's or so.  

Outside of some uncertainty regarding cloud cover and how much sun we see, lies questions with how much low-level moisture we will have to work with.  Computer forecast guidance is all over the place with regards to the surface dewpoints with some guidance mixing dewpoints into the upper 40's to lower 50's while other pieces of guidance keeps dewpoints well into the 50's to perhaps even lower 60's.  The extent of the thunderstorms and threat for severe thunderstorms will be highly dependent on what happens with the dewpoints.  Basically the higher the dewpoints, the greater likelihood for severe thunderstorms. 

Given the potential for temperatures ranging from the mid-70's to low 80's, and dewpoints either in the 50's or 60's, when coupled with the steep mid-level lapse rates this would yield at least a modestly unstable airmass (if we see more sunshine and temps closer to 80F or into the lower 80's and are able to keep dewpoints in the 60's we would be looking at a much more unstable airmass).  This would provide enough fuel for shower and thunderstorms to develop ahead of the cold front.  

Winds aloft are also expected to strengthen throughout the afternoon in response to the amplifying trough and approaching shortwave.  500mb winds are expected to strengthen to as much as 50-60 knots region wide with 700mb winds expected to be around 30-35 knots.  These values will yield 0-6km shear values on order of 35-45 knots which is more than enough for not only organized thunderstorms but for some of the storms to become strong to severe:

 All in all tomorrow will feature the development of showers and thunderstorms in the afternoon across New England.  Depending on the degree of instability we are able to realize (all dependent on degree of sunshine and how high dewpoints are) some of these thunderstorms could quickly become strong to severe and pose a threat for large hail and strong to damaging wind gusts.  Given the degree of wind shear aloft, with enough instability we could see some supercell thunderstorms develop which would enhance the potential for larger hail and any rotation would have to be closely watched as well.