Weather for New England and the Northeast

Area Forecast Discussion
National Weather Service Boston/Norton MA
710 AM EDT Mon Jul 6 2026

WHAT HAS CHANGED
The Flood Watch has been expanded across the rest of southeast Massachusetts into Tuesday.

KEY MESSAGES

* Periods of heavy rain and possibly a few embedded thunderstorms today into Tuesday across parts of Connecticut, Rhode Island, and southeast Massachusetts. Localized flash flooding possible dependent on if the heaviest bands setup in our region. Otherwise, rain overspreads the rest of the region through tonight but amounts will be lighter especially near the New Hampshire border.
* Summer warmth and humidity return for the latter half of the week. Mainly dry weather returns Wednesday into Thursday, But the risk for a few showers and thunderstorms may return by Friday perhaps lingering into Saturday.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION

The main forecast concern is the potential for localized flash flooding across parts of Connecticut, Rhode Island, and southeast Massachusetts into Tuesday. This remains a very difficult forecast as the narrow bands of potentially extremely heavy rain are quite difficult to forecast in terms of timing and locations. However, the environment in place does favor the potential for them to form.

Weak high pressure across eastern Canada was enforcing a shallow boundary, or a front separating two distinct air masses, in the vicinity of Connecticut, New York, and New Jersey. This boundary was being impinged upon by a modest southeast LLJ, or Low Level Jet, which is a fast moving ribbon of air in the lower atmosphere that injects moisture into storms, coupled with a PWAT, or Precipitable Water, plume of 1.5 to 2.0 plus inches.

The idea though is that you are combining winter like synoptic, or large scale, atmospheric features with summertime moisture parameters. That combination can lead to localized extreme rainfall events. This potential is indicated by various model suites printing out narrow bands of very high precipitation.

The issue is that these narrow bands of potentially extreme precipitation are depicted in a lot of different locations depending on what computer model you are looking at. This is quite common in these cases where the models are good at indicating the potential for localized torrential rain events, but struggle to pin the location.

Given the above, we have expanded the Flood Watch from Connecticut and Rhode Island across the rest of southeast Massachusetts. We are looking at widespread rainfall amounts of 1 to 3 inches, but localized 4 to 6 inch amounts would be possible within 6 hours if any narrow bands setup.

Not all the models show these narrow bands developing, but many of the CAMs, or Convective Allowing Models, which are high resolution micro scale computer models that better simulate individual thunderstorms, do and it is reasonable given the parameters in place. If they do develop, some CAMs focus it to our south while others bring it into our region. Regardless, the Flood Watch is certainly warranted given the potential if these bands are realized.

Across the rest of the region, rain amounts will be lighter especially towards the New Hampshire border. In fact, it may take until later tonight for the steady rain to finally reach northeast Massachusetts. Periods of rain will persist into Tuesday especially across eastern Massachusetts and Rhode Island as a closed 850 mb low, an area of low pressure about 5,000 feet up in the atmosphere, may setup a mid level deformation zone, which is a stretching and tightening of the atmosphere that causes persistent, heavy rainfall to band together.

KEY MESSAGE 2 DESCRIPTION

As the shortwave, a smaller scale atmospheric disturbance or upper level low, departs the region, a mid level ridge axis, an elongated area of high pressure that brings clearing skies and warmer air, builds over the region with mainly dry weather returning Wednesday into at least a good part of Thursday.

Rising height fields, which indicate warming and expanding air in the upper atmosphere, should allow summer like warmth and humidity to return. Highs may take a run at 90 degrees in some spots by Thursday.

The next shortwave trough may bring the risk for a few showers and thunderstorms returning by Friday which may linger into Saturday. This will depend on the timing of the shortwave and cold front.