DAYS 1-5 (JANUARY 31- FEBRUARY 4)
The arctic air mass that has frozen us decently well over the last few days will be on the way out today, although it will still be a cold day, running below normal for the end of January. The high & mid level clouds you see in the sky are in advance of the coming winter storm that will impact the region later Monday through Tuesday, with greatest impact Monday night. This will happen as low pressure heads from the Ohio Valley to the northern Middle Atlantic Coast. This low never turn into a power house, but it will have an elongated center, first with a west-to-east orientation south of New England, then in response to upper level low pressure will rotate counterclockwise to more of a south-to-north orientation as it passes south and east of New England Monday through Tuesday, before moving away and organizing into a more formidable storm system in the Canadian Maritime Provinces on Wednesday. After that, high pressure will move in providing us with fair weather and not-too-cold air for Thursday.
Before I go to the detailed forecast here is an updated run-down of the aspects of the coming storm…
Arrival timing: Snow arrives south to north Monday afternoon but may be mixed with rain South Coast, Cape Cod, and MA South Shore.
Storm peak (heaviest precipitation): Monday night to very early Tuesday.
Snow amounts: Slushy under 1 inch tip of Cape Ann MA, immediate South Shore of MA south of Plymouth, Buzzards Bay region eastward through Cape Cod. 1-3 inches middle of Cape Ann MA, immediate MA South Shore south of Boston to Plymouth, southward just inland of the MA South Shore south of Plymouth to the western side of Buzzards Bay, 3-6 inches immediate NH Seacoast to immediate North Shore of MA, Logan Airport, interior southeastern MA to Narragansett Bay, 6-12 inches elsewhere with highest amounts in the I-495 belt west of Boston especially higher elevations.
Rain vs. snow: A rain/snow line will spend most of its time near the shoreline with southeastern MA especially Cape Cod in rain longest. This rain/snow line may migrate northwestward for a while during the storm, or even oscillate in response to precipitation intensity and is the reason for a very sharp snowfall gradient in the forecast. When you see this, there is a higher-than-usual potential that areas in this sharp gradient zone need a forecast adjustment.
Coastal impact: While not extremely strong, some significant and persistent onshore wind from the east and northeast, with some strong gusts across Cape Cod, then eventually more from the north, will probably result in minor to possibly moderate coastal flooding for the Monday afternoon, early Tuesday morning, and Tuesday afternoon high tides, with the greatest threat likely for the latter 2 high tide cycles.
Power outages: This will be a higher water content snow, so isolated to scattered power outages are possible, especially where snowfall accumulations are 4 or more inches. The stronger wind gusts along the coastline and especially over Cape Cod may also result in a few isolated power outages. Not expecting widespread power problems.
TODAY: Increasing clouds. Highs 25-32. Wind N under 10 MPH.
TONIGHT: Thickening overcast.. Lows 15-22. Wind NE up to 10 MPH.
MONDAY: Overcast. Snow arriving south to north during the afternoon at least into the I-90 belt, may be mixed with rain South Coast / Cape Cod. Highs 26-33 except 33-40 South Coast / Cape Cod. Wind NE to E increasing to 10-20 MPH, higher gusts especially coastal areas by late-day.
MONDAY NIGHT: Overcast. Moderate to heavy snow except mix coast and rain Cape Cod evening, tapering off to a few rain/snow showers south to north overnight. Temperatures rise slightly to 28-35 except 35-42 coastal areas, warmest Cape Cod. Wind E to NE 10-20 MPH with gusts as high as 30 MPH inland, 15-25 MPH with gusts as high as 40 MPH coastal areas, except 25-35 MPH with gusts 50-60 MPH Cape Cod.
TUESDAY: Cloudy. Occasional rain & snow showers. Highs 35-42 morning, falling slightly in the afternoon. Wind NE to N 10-20 MPH with gusts to 30 MPH inland and 15-25 MPH with gusts to 40 MPH coastal areas except 45-55 MPH Cape Cod, especially in the morning and midday.
TUESDAY NIGHT: Mostly cloudy. Additional mix/snow showers evening. Lows 25-32. Wind NW 10-20 MPH, higher gusts.
WEDNESDAY: Partly sunny. Highs 33-40. Wind NW 10-20 MPH, higher gusts.
WEDNESDAY NIGHT: Partly cloudy. Lows 22-29. Wind NW 5-15 MPH, higher gusts.
THURSDAY: Mostly sunny. Highs 36-43. Wind NW 5-15 MPH becoming variable.
DAYS 6-10 (FEBRUARY 5-9)
Next low pressure area passes well north of the region on February 5 with a warm front / cold front combo meaning maybe a brief light mix then a chance of rain showers. Additional unsettled weather possible during the February 6-7 weekend and possibly February 8 as colder air from the west slowly makes its way toward this area. Too early for detail on precipitation chances at this time. Fair, colder weather to end this period.
DAYS 11-15 (FEBRUARY 10-14)
Temperatures start cold then moderate, unsettled weather threat mid to late period. Low confidence forecast with a lot of re-evaluation needed.