Severe Weather Coordination Message #2 – Wednesday Afternoon and Evening 7/22/20 and Thursday Afternoon and Evening 7/23/20 Severe Weather Potential

Hello to all…

..Isolated to Scattered Strong to Severe thunderstorms are possible to likely across Western and Central Massachusetts, Connecticut and Northwest Rhode Island. Strong to damaging winds, hail, frequent lightning and heavy downpours leading to urban and poor drainage flooding are the main threats. Threat timeframe has shifted to the 3-10 PM Wednesday timeframe..
..The Storm Prediction Center (SPC) has placed Western and Central Massachusetts and Western and Connecticut in a Slight risk for severe weather and Eastern Connecticut into Rhode Island and Eastern Massachusetts except for east coastal Massachusetts and Cape Cod and the Islands in a marginal risk for severe weather for Wednesday Afternoon and Evening. This represents a shift west in the highest severe weather potential and will be highly dependent on warm frontal position and heating and destabilization..
..It is also noted that there continues to be a marginal risk for severe weather for much of Southern New England Thursday. Details on the severe weather potential for Thursday will be posted in future coordination messages and will depend on the evolution of strong to severe thunderstorms Wednesday Afternoon and Evening..
..SKYWARN Self-Activation will monitor the severe weather potential for Wednesday Afternoon and evening. SKYWARN Self-Activation will also monitor the severe weather potential for Thursday Afternoon and Evening as needed..

After a brief break in the humidity on Tuesday, a warm front will bring the humidity back into the region during Wednesday Afternoon and evening and allowing for the potential of isolated to scattered strong to severe thunderstorms. The headlines depict the current thinking. Key factors on the severe weather potential for Wednesday are as follows:

1.) The position of the warm front and how far north it makes it through Southern New England. Recent model trends have shifted it back a bit to the southwest so that the warm front will be through at least Western and Central Massachusetts and Western and Central Connecticut but not into parts of East-Central Massachusetts and Rhode Island so the slight risk area was shifted a bit westward and areas to the east continue to be in a marginal risk for severe weather. The position of the warm front and the ability for the region to heat and destabilize behind the warm front will determine the severe weather potential in the area.
2.) There have been some showers and a few non-severe thunderstorms Wednesday Morning and they have swung through the area. Satellite imagery shows clearing to allow for heating and destabilization and the key factor will be that heating and destabilization and if that continues in the warm sector with the warm frontal passage.

It is noted that there is also a marginal risk for severe weather for much of Southern New England for Thursday. The severe weather potential for Thursday is associated with a cold front and there maybe wider coverage across the region for severe weather on Thursday though some of this will hinge on what develops for strong to severe thunderstorms and any cloud cover from Wednesday Afternoon and evening. Details on the severe weather potential for Thursday will be posted in future coordination messages.

SKYWARN Self-Activation will monitor the severe weather potential for Wednesday Afternoon and evening. SKYWARN Self-Activation will also monitor the severe weather potential for Thursday Afternoon and Evening as needed. Another coordination message on the Thursday severe weather potential will be posted either by 1100 PM Wednesday Evening or 1000 AM Thursday Morning depending on severe weather operations this Wednesday Afternoon and Evening. 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 Experimental 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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