Author’s note: I apologize to my readers for not updating the forecast over the weekend. I was pulled away due to a family illness. I will NOT be updating the forecast this Thursday, Dec. 11, due to this on-going illness.
Forecast discussion: If you look back to my last forecast, The European model had been forecasting a major low pressure system to form offshore of the Mid-Atlantic. Well, three days later, the model was the best choice. We are expecting a strong low to bring us heavy rainfall and strong winds. But, we have several advisories in effect at the moment for eastern Massachusetts.
At this time, a Winter Weather Advisory is in effect for Boston from 7 p.m. until 5 a.m. Tuesday morning. This is due to the precipitation starting as a wintry mix of snow, sleet, and rain. Due to the cold temperatures we had on Monday, there will be enough cold air in the lower levels of the atmosphere to create the frozen precipitation. This would cause some travel problems if you are heading out to do your Christmas shopping. Eventually, temperatures will warm and change the precipitation to just rain. Also, a Flood Watch is in effect from 6 a.m. Tuesday until 1 a.m. Wednesday, as we are expecting anywhere between 1-3 inches of rain. So, there may be some minor street flooding and large puddles on the highways. A Wind Advisory is in effect for the eastern coastline, as well as the Cape and Islands, as we are expecting wind gusts as strong as 50 mph at times. Finally, a Coastal Flood Advisory is in effect from 11 a.m. until 3 p.m. Tuesday. This is due to northeast winds bringing water towards the lower beaches and shorelines during high tide. There may be some minor flooding along roads which face the shore, as well some minor beach erosion.
In terms of the forecast, we are awaiting a low pressure system that is slowly forming well offshore of North Carolina. This low will move north and west, and center itself over Long Island, NY by tomorrow night. From this low, we will see increased precipitation through the day, with a wintry mix early Tuesday morning, to heavy rain expected by the end of the morning commute. We will also see strong winds, as wind gusts in some areas could reach 50 mph. The heaviest precipitation will move north of us Tuesday night, but we will continue to see lingering showers. There is the possibility of seeing a dry slot, or where strong lows like this have an area where there is no rainfall. Patchy fog is expected, as winds will be diminishing through the overnight.
As we move into Wednesday, the low’s center will become stalled. It will remain around the Long Island area into Wednesday morning. So, we will see lingering showers throughout the day. But, by the afternoon, the low will move slowly east, allowing for colder air on the backside of the center to filter back over eastern Massachusetts. By Wednesday night, the precipitation may end as some snow showers west of Boston. No accumulation is expected, due to the wet grounds, and temperatures will be in the upper 40’s for high temperatures.
The models continue to show the low lingering offshore of Cape Cod for Thursday, so there is the chance for some lingering showers and drizzle. The low will finally be kicked out into the Gulf of Maine by Thursday night, allowing for a weak high pressure ridge to protect us from any more wet weather.
As we head into the extended period, a strong high pressure system will remain over the eastern U.S., providing us with partly to mostly sunny skies and seasonable temperatures. We will go into early next week with highs in the lower to middle 40’s.
72 hour forecast:
Tonight: A wintry mix of sleet, snow and rain will become all rain by 4 a.m. We will see a low of 32 with temperatures rising during the overnight.
Tuesday: Showers becomes heavy rain by 9 a.m. It will remain windy with very strong wind gusts. We will see a high of 48 with northeast winds of 23-27 mph with wind gusts of 40-45 mph.
Tuesday night: Heavy rain tapers to showers by 11 p.m. There may be lulls in the showers going into sunrise. We will see a low of 43 and patchy fog is expected with winds diminishing to 14-18 mph from the north-northwest.
Wednesday: Showers with a high of 47 in the morning. Temperatures will be slowly dropping after 11 a.m.
Wednesday night: Lingering rain showers with a low of 36.
Thursday: Isolated rain showers with a high of 42.
Thursday night: Isolated rain showers end by 7 p.m. with clearing skies after 3 a.m. We will see a low of 32.
Friday: Mostly sunny. Highs 39-42, lows 31-34.
Saturday: Partly sunny. Highs 41-44, lows 32-35.
Sunday: Mostly sunny. Highs 43-46, lows 33-36.
Monday: Mostly sunny. Highs 44-47, lows 32-35.