Severe Weather Coordination Message # 2 – Tuesday 7/6/21 Severe Weather Potential

Hello to all…

..Isolated to Scattered Strong to Severe Thunderstorms are likely Tuesday Afternoon and Evening across Southern New England with strong to damaging winds, hail, frequent lightning and heavy rainfall with urban and poor drainage flooding are the primary threats. The Storm Prediction Center (SPC) has continued all of Southern New England in a Slight risk for severe weather with the timeframe between 1-8 PM Tuesday Afternoon and Evening..
..SKYWARN Self-Activation will monitor the severe weather potential for Tuesday Afternoon and Evening..

Heat and humidity will return to Southern New England Tuesday and with an impulse in the atmosphere, it will set the stage for isolated to scattered strong to severe thunderstorms during the Tuesday afternoon and evening hours. The headlines depict the current thinking with little change from last night. Key factors remain and include:

1.) Wind shear values will be marginally conducive for severe thunderstorms with damaging wind gusts. If that shear becomes stronger, it could potentially mean a greater more widespread severe weather risk and this will be monitored. Certain mid-level instability parameters are also marginally favorable for severe thunderstorm development.
2.) There is some cloud cover in the region and with the overnight thunderstorms being a bit more robust than modeled, it does create some uncertainty on whether the impulse in the atmosphere will break and capping to allow for strong to severe thunderstorm development. At this time, models still show the potential across much of Southern New England and despite cloud cover that is in the area, instability remains elevated over the region and should increase with breaks in the clouds noted on satellite imagery.
3.) Timing of strong to severe thunderstorm development in the area as some models show earlier timing but near the time of peak heating and other models show the development towards late afternoon and evening. This timing would be favorable but if showers and thunderstorms build in earlier towards mid to late morning or produce more cloud cover, this could limit the severe weather potential. At this time, models are giving a favorable timeframe for strong to severe thunderstorm development.

It is noted that we are also in a marginal risk for severe weather in portions of Southern New England for Wednesday. This will be discussed as needed in a future coordination message posted by 11 PM Tuesday Evening.

SKYWARN Self-Activation will monitor the severe weather potential for Tuesday Afternoon and Evening. This will be the last coordination message on the Tuesday severe weather potential as we shift into operations mode. Below is the NWS Boston/Norton Area Forecast Discussion, Enhanced Hazardous Weather Outlook and SPC Day-1 and Day-2 Convective Outlooks:

NWS Boston/Norton Area Forecast Discussion:
https://kamala.cod.edu/ma/latest.fxus61.KBOX.html

NWS Boston/Norton Enhanced Hazardous Weather Outlook:
https://www.weather.gov/box/ehwo

SPC Day-1 Convective Outlook:
https://www.spc.noaa.gov/products/outlook/day1otlk.html

SPC Day-2 Convective Outlook:
https://www.spc.noaa.gov/products/outlook/day2otlk.html

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: rmacedo@rcn.com
http://ares.ema.arrl.org
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