Severe Weather Coordination Message #2 – Wednesday 7/21/21 Severe Weather Potential

Hello to all…

..Isolated to Scattered Strong to Severe Thunderstorms are likely between 1 PM-9 PM Wednesday Afternoon and Evening across much of Southern New England with the Storm Prediction Center (SPC) placing areas along and south of the Mass Pike in Massachusetts, Connecticut and Rhode Island in a Slight Risk for severe weather with areas north of the Mass Pike in a marginal risk. Strong to damaging winds, hail, frequent lightning and urban and poor drainage flooding to flash flooding are the main threats..
..The Storm Prediction Center (SPC) has indicated an 80% chance of a Severe Thunderstorm Watch for areas south of the Mass Pike, particularly Eastern Connecticut, Rhode Island and Southeast Massachusetts via their Mesoscale Convective Discussion..
..SKYWARN Self-Activation will monitor the severe weather and flood potential Wednesday Afternoon and Evening..

We are continuing to compile reports, pictures and videos from the last few days of severe weather and flash flooding. If time allows, a post severe weather and flash flood coordination message around the weather events this past weekend and potentially a summary of all the various events going back to the week off July 4th will be compiled and posted by the end of this week. It has been a very active month of July for areas from the Boston to Providence corridor north and west in the NWS Boston/Norton coverage area.

Tuesday’s severe weather stayed north and west of Southern New England across Northeast New York, Vermont and New Hampshire. Today’s severe weather potential is looking more robust particularly along and south of the Mass Pike across in Massachusetts as well as Connecticut and Rhode Island. The headlines depict the current thinking. Key factors for today include:

1.) Any lingering cloud cover from strong to severe thunderstorms Tuesday Night into early Wednesday. As of 930 AM, plenty of sunshine is occurring in the slight risk area in the region.
2.) Timing of the cold front through the region Wednesday and whether it is timed with peak heating and instability. This timing looks to be verifying at this time.
3.) Level of sufficiently strong wind shear in the atmosphere as well as maintaining higher dewpoints in the slight risk area. At this time, both of these are occurring as expected.
4.) Much of interior Southern New England from roughly a Boston to Providence line has been very wet so even non-severe thunderstorms that contain heavy downpours could result in greater flooding impacts than normal in these areas.

SKYWARN Self-Activation will monitor the severe weather and flood potential for Wednesday Afternoon and Evening. This will be the last coordination message for Wednesday’s severe weather potential. Below is the NWS Boston/Norton Special Weather Statement,  Area Forecast Discussion, Enhanced Hazardous Weather Outlook and SPC Day-1 Convective Outlook:

NWS Boston/Norton Special Weather Statement – Severe Weather Potential:

NWS Boston/Norton Area Forecast Discussion:

NWS Boston/Norton Enhanced Hazardous Weather Outlook:

SPC Day-1 Convective Outlook:

SPC Mesoscale Convective Discussion:

Respectfully Submitted,

Robert Macedo (KD1CY)
ARES SKYWARN Coordinator
Eastern Massachusetts ARES Section Emergency Coordinator
Home Phone #: (508) 994-1875 (After 6 PM)
Home/Data #: (508) 997-4503 (After 6 PM)
Work Phone #: 508-346-2929 (8 AM-5 PM)
Email Address:
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