Severe Weather Coordination Message #2 – Sunday 7/5/20 Severe Weather Potential

Hello to all…

..Isolated to scattered strong to severe thunderstorms are likely Sunday afternoon and evening particularly over Northeastern and Central Massachusetts and into North-Central Rhode Island but the potential could extend southwest back into parts of Western Massachusetts and North-Central and Northeast Connecticut. Strong to damaging winds, hail, frequent lightning and heavy rainfall leading to urban and poor drainage flooding are the primary threats but an isolated tornado is a secondary threat..
..The Storm Prediction Center (SPC) has extended the Marginal Risk into Northeast Connecticut, Rhode Island and the Connecticut River Valley of Western Massachusetts east into Central and Eastern Massachusetts for today. Severe weather potential timeframe is between about 2-10 PM Sunday Afternoon and Evening..
..SKYWARN Self-Activation will monitor the severe weather potential for Sunday Afternoon and Evening..

..It has been an active week for severe thunderstorms and localized flooding across parts of Southern New England. A Post Severe Weather Coordination Message will be posted on the various events from the week of 6/28 later this Sunday Morning ahead of today’s severe weather if time allows..

There remains the potential for severe weather on Sunday Afternoon and Evening and the marginal risk for severe weather has been expanded southwestward and westward into parts of North-Central Connecticut, Rhode Island and Western Massachusetts from the Connecticut River Valley east into Central and Eastern Massachusetts. The headlines depict the current thinking. Key factors include:

1.) The level of mid-level dry air in the atmosphere and whether too much of dry air stunts severe thunderstorm development. At this time, this is expected to be overcome particularly from the Connecticut River Valley eastward with the most favorable area in Northeast Massachusetts. There will be a sharp cutoff between higher and lower dewpoint air that will setup in Central New England and areas along and to the east of that higher/lower dewpoint air line will see the greatest risk for severe weather development.
2.) The level of forcing or a trigger in the atmosphere to take advantage of the favorable instability and wind shear profiles in the atmosphere or whether the level of instability and wind shear compensates for a marginal trigger or forcing in the atmosphere. A cold front will move into the area along with the line between higher and lower dewpoint air towards evening which will set the area for the most favorable conditions for severe weather potential.
3.) There is the possibility for two rounds of activity. One in Western and Central Massachusetts and Northern Connecticut spreading eastward between 3-6 PM with another round after 6 PM to 10-11 PM that would be focused in Northeast Massachusetts but other areas should monitor.

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

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

NWS Boston/Norton Special Weather Statement:
https://kamala.cod.edu/ma/latest.wwus81.KBOX.html

NWS Boston/Norton Hazardous Weather Outlook:
http://kamala.cod.edu/ma/latest.flus41.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

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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