November has been a dry, warm month for much of the northeast so far this year, and arguably so a much needed break in that regard. Unsettled weather, however is making it’s return this week as indicated by the SREF’s upper level pattern.
This map is valid 12z at 11.17.2011 and while there is some substantial spread in the overall amplitude of this upper level feature, it is beginning to look more likely that it will become a factor in the rain later this week.
We are looking at a shortwave trough in the upper level, that the GFS is even weaker and more progressive with. You have to remember folks, zonal patterns favor milder temps and weaker development.
The ensemble is hinting at the possibility of a low somewhere along this shortwave that would then bring more unsettled weather to New England. This would happen along a stalled frontal boundary over the interior. With warm temperatures in place (well above normal in many spots) the potential for wet weather on Wednesday can’t be ruled out.
Cooler temperatures would follow, and a return to more zonal flow afterwards keeps those temps moderating.