Thunderstorms, flooding rains of over 2 inches possible once again for Massachusetts, Rhode Island, Connecticut

Massachusetts, Rhode Island, and Connecticut could once again see heavy rains and flooding which could put a nice dent into the drought conditions in southern New England.

According to the National Weather Service, after mainly dry conditions today and increased
risk for rip currents, periodic chances of scattered showers and thunderstorms are expected early to mid-week, potentially lingering into Thursday. Increasing potential for heavy rain late Tuesday through Wednesday with at least localized flash flooding possible.

During the day on Monday, a warmer day in the low to mid 80s and upper 70s for coastal areas are expected. There is still potential for scattered showers and thunderstorms late afternoon/evening though guidance is still lacking agreement on the coverage and convective potential. This keeps us at probabilities of less than 40% still with west/central southern New England being more favored.

Model guidance has remained generally consistent with a deepening trough into Tue/Wed with a strong signal for above normal moisture (120-170% of normal) advecting into the region by Tuesday. ECMWF models show 40-75% probability for 1+ of rainfall later Tuesday into Wednesday and 10-40% for 2″+ across a good portion of southern New England. The deterministic guidance over the last 24 hours of runs has showed a large footprint of 2″+ amounts across the region in that same timeframe. Training will increase the risk for flash flooding with more “scattered” occurrences as opposed to an isolated case or two. While the recent deterministic runs of the Canadian and GFS have gone more on board with the heavy rain potential, their ensemble guidance still have shown solutions leaning toward a weaker low and differing track resulting leading to lesser rainfall amounts. There is still a signal for
localized heavy rain/flash flooding within these solutions; however, they are more isolated or localized. There is still uncertainty; however, there is increasing confidence for widespread rain with at least localized heavy downpours/flash flooding possible in spots, particularly later Tuesday through Wednesday. Depending on the track of the low, showers may linger through Thursday.