DAYS 1-5 (MARCH 12-16)
First, this reminder: If you have manual clocks and didn’t change them yet, move them forward 1 hour! Daylight Saving Time began at 2:00 a.m. today! Now, onto the weather, and today will be a very nice late winter Sunday under the influence of a small high pressure area. There will be an exception though, and that is Cape Cod and portions of the South Shore to South Coast just to the west of there, under a canopy of ocean-born clouds with a north northeast wind and low level moisture in the atmosphere. Gradually, today’s wind will be turning a little more northeast to east, and eventually, this cloud area will start to expand westward, so more coastal areas may lose the sunshine as we go through the day. However, it will at least be dry in the areas that see the cloudiness for any outdoor plans… Now, to the storm threat. A significant late-winter storm is on its way, impacting our region starting Monday and lasting into a good part of Wednesday. This doesn’t mean 3 days of full-on stormy weather. That peaks during Tuesday, but the lead-in Monday comes as clouds thicken up (although this may be taking place above a blanket of lower clouds already in place anyway). Low pressure is going to be passing just to our south and in an elongated form with a bit of a dumb-bell spin upcoming as the low becomes captured by its upper level partner and ends up doing a cyclonic loop probably just off to the southeast and east of New England Tuesday through early Wednesday. It will also be intensifying during this time a lot closer to us than many of its predecessors have done, and some of those were actually weakening as they came through, not intensifying. So this particular storm is a different animal compared to many we’ve seen this season. The main precipitation arrives late Monday night and lasts until late Tuesday night or early Wednesday morning. I think a snow or mixed rain/snow start is likely inland and a start as rain in the coastal plain for sure. It likely rains for a number of hours at the start of the storm in places like Providence and Boston and all those coastal communities, but as the storm intensifies offshore, the process of dynamic cooling will drag down cold air from above and change that rain to snow for most of, and eventually all of the region. This will take place last over Cape Cod, which will end up with the least amount of snow from the storm, with amounts building up as you head west and north. My outline of p-type and snow amounts for this system goes like this. Starts a couple hours either side of midnight Monday night / Tuesday morning as mix/snow for southwestern NH and north central MA, mix/rain south central MA, and rain eastern CT through RI and all of eastern MA. Flip to snow takes place in a general west to east motion over the inland areas (west and northwest of the coastal plain) by around dawn or shortly after, and into the coastal communities including the cities of Providence and Boston by around mid morning Tuesday, and lastly to Cape Cod by around noon Tuesday. One caveat about that: A potential dry slot can get into the South Coast region during Tuesday morning-midday which means that little or nothing may fall for an hour or two or three, which would make the change-over timing temporarily a moot point. Once precipitation resumed, however, it would be snow, or quick rain to snow, and I suspect most of what falls on Cape Cod will be snow for the balance of Tuesday afternoon into Wednesday morning. It will be Tuesday afternoon and evening that most of the snow accumulation is seen, and my first call on that is a slushy coating to 2 inches immediate South Coast including Cape Cod, 2-4 inches just inland from South Coast through the South Shore, 4-8 inches Providence up I-95 belt including Boston and the MA North Shore to the NH Seacoast and as far west as south central MA and northeastern CT with the potential for over 8 in the higher elevations of the 4-8 area, 8-12 inches from about I-495 from I-90 northward to include Worcester northward to southwestern and interior southern NH, with 12+ potential in the highest elevations of the 8-12 area. There may actually be a third low center (tertiary low) that rotates all the way around and brings one final batch of heavier snowfall into eastern areas early Wednesday morning before everything winds down during the day as spotty snow and rain showers. Snow load issues bring about the threat for damage to trees and power lines, and resultant power outages. Where this combines with wind it will be even more of an issue. And the wind aspect of this storm is significant. We start out with east and northeast winds increasing as the low center starts to pass by to the south, and then as the elongated set of lows pivots, our winds will back more to the northeast and north with time during Tuesday and into Wednesday (eventually north to northwest). Strongest wind gusts will be in coastal areas, and they may exceed 50 MPH there (Cape Ann, South Shore, Cape Cod most vulnerable to this). Thankfully, our tides are on the astronomically lower side, so while there will still likely be some coastal flooding and splashover at high tide times, it should be limited somewhat. Folks in coastal communities most vulnerable to storm-driven tidal issues should still be ready for minor to moderate flooding issues. Things calm down nicely during Wednesday night as the storm finally pulls away, and high pressure builds in for a nice “recovery” day Thursday.
TODAY: Sunshine except lots of clouds Cape Cod and MA southern South Shore to eastern South Coast, eventually expanding west and north, limiting the sun in more coastal areas with time. Highs 40-47. Wind N-NE 5-15 MPH.
TONIGHT: Mostly cloudy. Lows 28-35. Wind NE-E up to 10 MPH.
MONDAY: Cloudy. Highs 39-46. Wind E up to 10 MPH.
MONDAY NIGHT: Overcast. Snow/mix/rain arriving (snow favoring higher elevations inland, rain favoring most areas initially). Lows 33-40. Wind E-NE 5-15 MPH, higher gusts in coastal areas.
TUESDAY: Overcast. Snow well inland and higher elevations. Rain changing to snow elsewhere. Snow will become heavy at times. Temperatures fall slightly to 30-37. Wind NE-N 15-25 MPH inland and 25-35 MPH coast, with gusts above 30 MPH inland and above 50 MPH coast.
TUESDAY NIGHT: Overcast. Snow tapers off gradually but still can be heavy at times. See above discussion for accumulation expectations. Lows 28-35. Wind N 15-35 MPH, higher gusts especially in coastal areas.
WEDNESDAY: Mostly cloudy with snow and rain showers likely. Highs 35-42. Wind N-NW 15-30 MPH, higher gusts.
WEDNESDAY NIGHT: Mostly cloudy early, then clearing. Lows 25-32. Wind NW 5-15 MPH.
THURSDAY: Mostly sunny. Highs 41-48. Wind NW 5-15 MPH.
DAYS 6-10 (MARCH 17-21)
Unsettled weather potential late March 17 into March 18 then a drier trend. Starting mild, then cooling. Vernal Equinox – March 20.
DAYS 11-15 (MARCH 22-26)
Early days of spring continue to look active with the good shot at a couple low pressure systems impacting the region with rain/mix/snow potentials and temperatures back to below normal.