Bands of heavy rain could bring up to 6 inches in some parts of Southern New England. Here’s where flood watches are in effect.

Greater Boston should avoid the heaviest rainfall

Heavy rain will bring a flood risk to Southern New England on Monday.Boston Globe

The first half of the year in Boston started as the driest on record, and after this week’s four-day heatwave, the need for rain is even more acute.

However, we’re going to see an atmosphere that may bring us too much rain, too fast, overwhelming some of our parched soils and leading to excessive runoff. This setup has sparked flood watches for Southeast Mass., Rhode Island, and all of Connecticut through Tuesday morning and afternoon.

Most of the heavy rain will pick up Monday night into early Tuesday as bands of steady to heavy rain organize and slowly move over the region.

Boston will continue to stay mostly dry until high pressure finally breaks down on Monday evening and scattered showers move north.

Flood watches are in place for portions of Southern New England through Tuesday afternoon.Boston Globe

Repeat storms over the same areas, with some torrential downpours at times, will result in water pooling in low-lying areas, along with water levels jumping towards minor flooding stages in rivers and creeks near the southern coast.

This time of the year, it’s very difficult for us to see all-day or multi-day rain because weather systems are usually not that intense. However, an unusually strong and slow-moving weather system will pass just south of Southern New England throughout Monday night and early Tuesday, bringing the heaviest rain by the southern coast while Boston sees mostly showers.

Scattered to steady rain will push through Southern New England until Tuesday afternoon.Boston Globe

There’s going to be quite a rain shield with this system, and we suspect that somewhere in Southern New England, most likely Connecticut, Rhode Island, or perhaps Cape Cod, there’s going to be a 5-inch or more bullseye of rainfall by mid-Tuesday.

That’s a lot of water on the roads for the Tuesday morning commute, so make sure you’re giving yourself extra time as you head out the door for the day.

Boston should land on the lighter side of rain totals with this rain event, but can certainly see rain totals reach an inch to an inch and a half by Tuesday afternoon.

Showers will linger throughout Southern New England on Tuesday.Boston Globe

Sharp divide in who sees rain and who doesn’t

Contrast that with the fact that the area of rain will be very narrow and the northern edge will have a sharp gradient. Areas just north of the Mass Pike may not see much rain at all, while areas south of the Mass Pike see well over an inch.

Boston winds up on the lighter side of rain totals. Showers eventually reach Boston late Monday, but the heavier downpours will likely remain south of the city. Boston may see a bit steadier rain on Tuesday morning than on Monday.

Rain totals through Tuesday may reach over 4 inches in portions of Connecticut and Rhode Island.Boston Globe

The heavy pockets of showers and thunderstorms will slowly overspread Connecticut, Rhode Island, and Southeast Mass. throughout Monday night and persist through the morning. The rainfall will make its most northward progression during the overnight hours and set up a soggy Tuesday morning across Greater Boston and, of course, areas south.

Rain should actually push into Northern New England on Tuesday, too, but precipitation should stay on the lighter side.

Boston will begin to see showers break up during the afternoon, but a sprinkle or two can remain through the commute home.

With plenty of moisture in the atmosphere, there will be a risk of a storm or two dumping heavy downpours at times, especially over the South Coast and the Cape on Tuesday morning, setting up a low-end risk for a flash flood.

There is a low chance of flash flooding across Eastern Mass. and Rhode Island on Tuesday.Boston Globe

Staying cool in July

Due to the combination of clouds, rain, and onshore flow, Boston is expected to reach the upper 60s on Tuesday, making you fish for a light jacket before you head out the door.

Northern New England will actually be the warmest on Tuesday, with highs nearing 80 degrees under partly sunny skies across areas like Burlington, Vermont, and Bangor, Maine.

Highs on Tuesday will remain cool, settling in the upper 60s across Greater Boston.Boston Globe

Tuesday breakdown

Greater Boston: Scattered showers, cool. Highs to the upper 60s. A little breezy.

Central/Western Mass.: Scattered showers, cool to the 60s across the board.

Southeastern Mass.: Scattered showers with some heavy downpours mixed in, mostly in the morning. Highs to the upper 60s. A little breezy.

Cape Cod and the islands: Scattered showers, a bit breezy. Highs to the mid and upper 60s.

Rhode Island: Scattered showers with heavy downpours mixed in, especially during the morning. Highs to the upper 60s and low 70s.

The forecast across Boston for the next seven days.Boston Globe

New Hampshire: Scattered showers with highs pushing near 70 degrees.

Vermont/Maine: Scattered showers across the southern half of both states, turning partly cloudy and warmer north. Highs in the upper 60s and low 70s south, near 80 north.

Connecticut: Scattered showers with pockets of heavy downpours mixed in during the morning. Drying out in the afternoon. Highs to the low 70s.

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