Forecast discussion: High pressure brought another beautiful day of sunshine to Boston, and the rest of Southern New England, on Wednesday. However, we will begin to enter an unsettling weather pattern. This pattern will bring wet weather showers to our weekend, something we have not seen in several weeks.
Right now, I have been watching a low pressure system passing into Quebec, Canada. This low has been bringing different scenarios to the computer models over the last few days. However, I have come to the conclusion that most of the precipitation with this low will pass over Massachusetts. So, I am adding isolated showers and thunderstorms back into the forecast. The best chance to see this precipitation will be by mid-afternoon. Meanwhile, a frontal boundary offshore will be giving us more moisture as we head into the weekend.
The frontal boundary will slowly come towards the coast. It is being pushed back due to a blocking ridge of high pressure in the Atlantic. This front will have a few weak low pressure systems form on it, and move into the region. So, as we enter Friday, we may see scattered showers from the system. Also, the humidity will be increasing once again, as we will remain with southwest winds.
The frontal boundary will remain stationary through the weekend. So, we will continue to see the risk of scattered showers and thunderstorms throughout Saturday and Sunday. The previous model runs felt we would clear out by Sunday afternoon. But, both the European and American models suggest now we will not see any clearing until early Monday morning. High pressure over the central U.S. will bring partly to mostly sunny skies for early next week.
Meanwhile, in the tropics, the National Hurricane Center is watching a well-defined low pressure system 900 miles east of the southern Windward Islands. There is a chance that the system could become a tropical depression within the next 48 hours. There is a 50 percent chance for formation within the next 48 hours, but also within the next five days.
72 hour forecast:
Tonight: Clear skies with a low of 62.
Thursday: Partly sunny by noon with the chance for an isolated mid-afternoon showers and thunderstorms. We will see a high of 80 with southwest winds of 11-14 mph.
Thursday night: Mostly cloudy with isolated showers and a low of 64. Winds will come from the southwest at 3-6 mph.
Friday: Cloudy with scattered showers. We will see a high of 82.
Friday night: Mostly cloudy with scattered showers and a low of 66.
Saturday: Partly sunny with scattered showers/thunderstorms by 10 a.m. We will have a high of 76.
Saturday night: Scattered showers/thunderstorms with a low of 65.
Sunday: Scattered showers until the early evening, with clearing skies after midnight. Highs 74-77, lows 64-67.
Monday: Mostly sunny. Highs 78-81, lows 64-67.
Tuesday: Partly sunny. Highs 81-84, lows 65-68.
Wednesday: Mostly sunny. Highs 78-81, lows 61-64.