Weekly Significant Weather Outlook
Showers and a Few Thunderstorms Today – Some with Heavy Downpours with a Risk of Localized Flash Flooding Today
Clusters of showers and possibly embedded thunderstorms will be prevalent across southern New England today. Some of the showers will contain very heavy downpours, and pockets of flooding likely in urban areas and other poor drainage areas. A few small streams may flood in in areas (such as central MA) that received heavy rain last week and where streams are already running high from prior heavy rain. In particular, there can be a risk of flash flooding of small streams should there be repeated cells of heavy showers/thunderstorms moving over the same area (a process referred to as “training” by meteorologists). Although a band of very heavy rain was moving through eastern MA and RI at the time of this writing and will pass offshore sometime mid-morning, additional heavy showers are likely to develop later this morning into this afternoon. Rainfall amounts are expected to be highly variable today – generally a half to an inch, but isolated pockets of 2 to 4 inches are possible.
There is also a risk of a few thunderstorms with localized strong wind gusts this afternoon. In fact, some high-resolution models hint at a squall line or two mid to late afternoon across western and central sections. Although the instability usually needed for severe thunderstorms appears to be limited, there’s rather strong wind shear that could help organize any thunderstorms that should develop.
The cause of the wet weather is an elongated upper trough and approaching surface cold front into a very moist (humid) air mass. Surface dewpoints this morning were in the low 70s across most of the region. The amount of water vapor in the air (referred to as precipitable water) is over 2 inches, high even by summertime standards. Also, with high freezing levels, expect generally warm rain processes (versus the usual ice crystals growing into snowflakes high up and then melting on the way down). Warm rain processes are very efficient and can produce very high rain rates. In addition, southern New England will be situated under the right rear quadrant of an upper-level jet streak, an area of upper divergence and favorable for general upward motion. This could also favor areas of downpours in this very moist air mass and possibly a few thunderstorms later in the afternoon if there should be sufficient instability.
Rest of the Week
Tuesday and Wednesday look to be dry. It’s less certain late in the workweek and into the weekend since our region could be vulnerable to a passing upper trough or two. In fact, a piece of the current rather elongated upper trough moving through the Northeast looks to separate and stagnate over the southern Appalachians. Although this may have no effect on our weather, there is a slight risk that any stronger trough passing through the Great Lakes could pull some of this energy further north in our direction (not looking likely at the moment but cannot rule out for late in the week). Chances are that any rain late in the week or weekend would be in the form of passing showers and not an all day washout.
Atlantic Basin Hurricane Activity
Now that we’re in August, will be taking a closer look at the tropics as the core of the hurricane season approaches. At this time, it’s quiet with no tropical cyclone formation expected in the next 7 days. This is not too surprising, since an expected to be significant El Nino phenomenon is developing. El Nino is the phenomenon that results in anomalously warm eastern Pacific tropical sea surface temperatures, which in turn results in higher than normal convective activity in the eastern tropical Pacific Ocean. That higher level of convective activity in turn tends to rev up an upper-level subtropical jet stream, which then in turn tends to shear apart any incipient tropical cyclones in the main development region of the tropical Atlantic. Thus, El Nino acts to suppress Atlantic Basin hurricane activity. It does not necessarily eliminate hurricane development in the Atlantic Basin, however, especially since storms may still form outside (or on the periphery) of the main development region such as near the Bahamas or the Gulf region. Also, sea surface temperatures, which help fuel hurricanes, are high across much of the tropical and subtropical Atlantic. Therefore, it’s still important for people along the U.S. east and Gulf coasts to be prepared with a hurricane plan. Although the overall activity likely will be less than average, all it takes is one.
Next Message
The next message will probably be the weekly significant weather outlook scheduled for Monday August 10. Note: no weather blog messages will be available August 12-15 as the author will be on travel.
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The National Weather Service monitors the weather 24/7 and updates forecasts, watches, and warnings as necessary. For most of southern New England, refer to your local Weather Forecast Office for the latest forecast/warning information at weather.gov/box. For information from other Weather Forecast Offices, go to weather.gov and click on the location of interest on the map.
The frequency of this blog will depend upon the nature of the weather threat and availability of the author. Thus, for the latest information on weather forecasts and warnings, refer to the National Weather Service, which monitors and forecasts the weather 24/7.
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The BHOSC maintains a continuous daily observation record that dates from February 1, 1885 without interruption and provides educational information on weather and climate to area students and the community at large. Your support of BHOSC is much appreciated and enables this nonprofit organization to maintain the long-term climate record at the Blue Hill Observatory (longest continuous record in North America) and provide valuable educational resources on weather and climate via outreach to schools, site visits/tours, webinars, and conferences. For more information on the Blue Hill Observatory and Science Center, explore bluehill.org.
Message issued August 03, 2026 by:
Bob Thompson
Retired National Weather Service Meteorologist
Blue Hill Observatory and Science Center Board member
