Severe Weather Coordination Message #1 – Sunday Evening 9/12/21-Monday Morning 9/13/21

Hello to all…

..Isolated to Scattered Strong to Severe Thunderstorms are possible across Western Massachusetts and Western Connecticut Sunday Evening into early Monday Morning. There could be two rounds one during roughly 6-10 PM Sunday Evening timeframe and a second potentially more potent round between 12 AM-6 AM EDT Monday Morning. Strong to damaging winds, hail, frequent lightning, and heavy downpours leading to urban and poor drainage flooding are the main threats..
..The Storm Prediction Center (SPC) has placed Western and Central Massachusetts and Connecticut in a marginal risk for severe weather Sunday Night into Monday Morning and the Weather Prediction Center (WPC) has placed the same area in a marginal risk for excessive rainfall..
..SKYWARN Self-Activation will monitor the severe weather potential potential for Sunday Night into Monday Morning..

A front will move across Southern New England Sunday Night into Monday Morning. Typically, this unfavorable timing would not support severe thunderstorm development but due to strong shear, dynamics and lift from the front, there is the potential for isolated to scattered strong to severe thunderstorms. The headlines depict the current thinking. Key factors include:

1.) The instability levels and whether those levels are sufficient combined with strong wind shear and jet dynamics for severe weather potential.
2.) Whether severe thunderstorms in Central and Eastern New York presuming they develop as expected will maintain their intensity as they move into Southern New England.

SKYWARN Self-Activation will monitor the severe weather potential potential for Sunday Night into Monday Morning. Another coordination message will be posted by 1030 AM Sunday Morning. Below is the NWS Boston/Norton Area Forecast Discussion, Enhanced Hazardous Weather Outlook, WPC Excessive Rainfall Outlook and SPC Day-2 Convective Outlook:

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

WPC Excessive Rainfall Outlook:
https://www.wpc.ncep.noaa.gov/qpf/ero.php?opt=curr&day=2

SPC Day-2 Convective Outlook:
https://www.spc.noaa.gov/products/outlook/archive/2021/day2otlk_20210911_1730.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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