Record Warmth With a Sunday Washout (1/10/2016)

An area of strong low pressure will be passing well to the west of southern New England on Sunday and this track will allow for a warm front to push through much of southern New England.  With the passage of the warm front will come a highly unseasonably warm/moist air mass as temperatures and dewpoints will climb well into the 50's.  In fact, a few areas, could even get close to 60F.  This warmth will indeed set some records in some spots.

With the warmth, however, comes rain...and quite a bit of rain.  Some areas will pick up as much as 1-2'' of rain with a few locations perhaps picking up as much as 3-4'' of rainfall.  Given how the ground is partially frozen (especially the top layer) this could create some issues with puddles and localized flooding.  Below is a graphic from the January 9th 12z GFS computer forecast model showing Precipitable Water Values "PWATS" for early Sunday afternoon.  We see PWAT values around 1.1'' to 1.3'' which is pretty impressive for this time of year and suggestive of the heavy rain potential we will be seeing:

 

We will also see the potential for thunderstorms as well embedded in the heavy rainfall as some weak instability pushes in thanks in part to the warm/moist low-level airmass advecting in.  Its within any thunderstorms that some areas could pick up the 3-4'' of rainfall.  The thunderstorms could arrive in what is called a forced line of low topped convection.  Unlike warm-season thunderstorms which are formed mainly due to strong instability, these thunderstorms are formed from very strong wind dynamics aloft which forces air to rise upwards, hence the term "forced convection".

Below we see the forecast from the January 9th 12z GFS computer forecast model for 500mb winds (winds about 18,000ft off the ground) during the early afternoon hours on Sunday.  The mid-level jet streak modeled is about 80 knots or so and arrives from the SW.  Notice the area over CT/MA where the color shading goes from yellow to red.  At the edge of this boundary we call this the nose of the jet.  This provides a good focal area for enhanced lift (stronger winds arriving) and it is along this boundary we could see a forced line of convection develop.

With winds just above the surface fairly strong it is also possible some of these stronger winds are transported down to the surface, thus it could be fairly gusty at times.  If any convection does form or push into the region, this will also enhance the potential for some stronger winds mixing down to the surface.  All in all we could see winds gust as high as 40-50 mph across the region with the small potential for a gust or two reaching 60 mph.  Isolated to widely scattered power outages will be a possibility, however, they should not be a major issue.

After the passage of this storm system we will see the beginning of a drastic pattern change towards much colder weather and yes perhaps even some snow chances...but we'll talk about this in a few days.