Forecast discussion: Boston seems to enjoy Saturday lot more than usual. We seem to have an unwritten record, as today was the sixth straight Saturday in a row we had fair, dry weather. The day was cool, as east and southeast winds only allowed the high temperature of 80 degrees at Logan Airport. As we move into Sunday, but the high pressure system that has controlled our weather will begin to move further into the Atlantic. This will allow for both a surface and upper level low to move towards the east coast. It is very possible our six straight Sundays of no precipitation may come to an end.
We will not begin to feel the effects of the surface low until Sunday afternoon. Our winds will be increasing, and clouds will be increasing in the sky. There is the chance of seeing some showers arrive before sunset. As we head into Monday, the front will still be to our west, but precipitation ahead of it may be heavy at times, especially in isolated thunderstorms. The front will stall over us Monday evening, as a second surface low forms over New York. This low will help trigger some more precipitation on Tuesday.
However, the upper level low is going to be moving over the region at the same time. The upper level low will pull some very cold air for the middle of July down into the Northeast. With the upper level low on top of the surface low, this may create some very strong to possible severe thunderstorms. We could see rainfall amounts up to 3 inches by the end of Tuesday night.
By Wednesday, the computer models are showing the front inching its way off the shore of Cape Cod. It may take until sunset before we see the end of any showers or thunderstorms. High pressure will bring drier, cooler air in for Wednesday, followed by bright sunshine for Thursday and Friday.
Right now, next weekend looks a little unclear. The American model pumps quite a lot of moisture along the east coast, thanks to a weak disturbance which moves along the coastline. We would see some showers and thunderstorms by Saturday afternoon. The European model suggests the precipitation stays well south of us. For now, based on the last several weeks of the weather pattern, I will continue our streak of seven straight Saturdays of delightful weather. But, my confidence for Saturday’s forecast is low, due to the uncertainty between the models.
72 hour forecast:
Tonight: Clear skies with a low of 66.
Sunday: Increasing clouds through the day with scattered showers by 8 p.m. We will see a high of 87 with strong south-southwest winds of 17-21 mph.
Sunday night: Overcast with scattered showers and isolated thunderstorms with a low of 70. Winds will come from the south-southwest at 11-15 mph.
Monday: Scattered showers with isolated thunderstorms by the early afternoon. It will be humid with a high of 85.
Monday night: Showers/thunderstorms with a low of 71.
Tuesday: Showers and thunderstorms expected. Thunderstorms could be strong to severe. We will see a high of 82.
Tuesday night: Showers/thunderstorms continue with a low of 67.
Wednesday: Showers/thunderstorms end before sunset. Partly cloudy skies expected during the overnight hours. Highs 78-81, lows 62-65.
Thursday: Mostly sunny. Highs 80-83, lows 61-64.
Friday: There is the slight chance for a passing shower in the early morning. Otherwise, mostly sunny skies are expected. Highs 80-83, lows 62-65.
Saturday: Partly sunny. Highs 80-83, lows 63-66.