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Boston Weather: 38.0°F | A Few Clouds

Weather: Predicting the Weather

By Greg Lawson
STAFF METEOROLOGIST -- How appropriate that the first forecast of the semester be a difficult one! The synoptic situation is a tricky one. The jet stream, our major weather system mover, is well to our north, leaving surface highs and lows to head eastward sluggishly. Late summer and fall often see a large, broad high semi-permanently settled over the Mid-Atlantic Ocean. It is sometimes called a Bermuda high or a blocking high, and New England is currently sandwiched between it and another strengthening high over Ontario. The two are battling, leaving a stationary front roughly paralleling the east coast. Instead of the jet stream ushering through full-fledged frontal cyclones (surface lows), the stationary front will allow smaller, weaker disturbances to travel northeast along it. The challenge as to whether we’ll have rain this week is predicting where the stationary front will be and how often and how strong these disturbances (called short waves) will travel along it. The latest model runs indicate our best chances of rain are roughly 50 percent on Thursday.

Regardless of the precipitation, it is evident that the high to our northwest will govern our wind patterns. With the winds spiraling clockwise outward from its center, we will soon feel cooler, drier air from the Canadian Maritimes. This should last until the weekend, when the Canadian high finally dislodges and moves out to sea.

Extended Forecast

Today: Very Pleasant. Mostly clear skies. High 72°F (27°C).

Tonight: Mostly clear. Light northeasterly winds. Low 60°F (16°C).

Wednesday:Cooler with clouds arriving. High 68°F (20°C). Low 58°F (14°C).

Thursday: Cloudy with a chance of rain. High near 70°F (20-22°C). Low near 60°F (15-17°C).