DAYS 1-5 (DECEMBER 9-13)
A blocking pattern will be in control of our weather for the foreseeable future. This pattern features high pressure at upper levels over Greenland extending into eastern Canada, and for this period of time will thwart storm systems from fully impacting our region. Surface high pressure in eastern Canada provides fair and chilly weather today. Two low pressure systems make runs at the Northeast from the west during the course of the weekend. The first will fall apart well to our west sending only high and mid level clouds into our region Saturday as some lower clouds also move in from the ocean due to a northeasterly air flow at the surface. The second low will have slightly more success getting far enough east to give us a heavier overcast and its snow shield will be pushing into the region Sunday evening while it is running into the high and drying up. Net result – minor snow event, favoring western portions of the WHW forecast area, i.e. southwestern NH through central MA to eastern CT. With milder air in place, any of this that reaches the South Coast region would probably be at least mixed with if not all rain – but very light amounts would occur either way. High pressure regains control of the weather early next week.
TODAY: Mostly sunny. Highs 38-45. Wind N 5-15 MPH.
TONIGHT: Partly cloudy. Lows 28-35. Wind N up to 10 MPH.
SATURDAY: Partly sunny. Highs 38-45. Wind N to NE up to 10 MPH.
SATURDAY NIGHT: Mostly cloudy. Lows 28-35. Wind NE 5-15 MPH.
SUNDAY: Mostly cloudy. Chance of snow by late afternoon favoring central MA, southwestern NH, and snow or rain in eastern CT and RI. Highs 38-45. Wind NE 5-15 MPH.
SUNDAY NIGHT: Cloudy. Chance of snow, except rain/mix along the coast. Lows 28-35. Wind NE 5-15 MPH.
MONDAY: Partly sunny. Highs 35-42. Wind N 5-15 MPH.
MONDAY NIGHT: Mostly clear. Lows 18-25. Wind N up to 10 MPH.
TUESDAY: Mostly sunny. Highs 33-40. Wind N up to 10 MPH.
DAYS 6-10 (DECEMBER 14-18)
Guidance: Until GFS is fixed, cannot rely on it for this period of time. Typical beyond-day-4 uncertainties applied to other guidance along with known biases. Blocking continues. The high pressure area will likely be elongated from southern Greenland through eastern Canada during this period, with an upper level trough over the US Midwest to Northeast. Watching the December 15-17 window for a storm chance. Again guidance solutions (ensembles) are very wide-ranging with this system telling us there is still plenty of uncertainty as to the outcome for this area. My current idea is that we see a low pressure area that will head toward the Great Lakes initially but unable to continues, therefore undergoing some kind of redevelopment / east southeast movement. Questions to be answered include what type / variety of precipitation if we get direct impact, or does it end up moving so far south we get skirted or even missed? Fair, colder weather returns for the end of the period.
DAYS 11-15 (DECEMBER 19-23)
Blocking pattern expected to continue. Early hints are upper high pressure scoots back toward Greenland with another upper high in western Canada. In between is the trough position with disturbances dropping out of Canada, through the Great Lakes and Northeast. Again remember that with guidance uncertainties and the typical “too far in the future for details” applied that we can’t have any kind of high confidence on day-to-day details, but the idea is a chilly pattern with a couple opportunities for precipitation – probably favoring snow over rain. But we have a long way to go to fine-tune this pre-Christmas period of time everybody will be paying close attention to.