Severe Weather Coordination Message #1 – Saturday 6/18/21 Late PM and Evening Severe Weather Potential

Hello to all…

..Isolated to Scattered Strong to Severe Thunderstorms are possible late Saturday Afternoon and Evening across much of Southern New England with a timeframe of after 5 PM til 12 AM Saturday with strong to damaging winds, hail, frequent lightning and heavy rainfall with urban and poor drainage flooding as the main threats. The Storm Prediction Center (SPC) has placed much of Southern New England in a marginal risk for severe weather for Saturday..
..SKYWARN Self-Activation will monitor the severe weather potential for Saturday late Afternoon and Evening..

An impulse in the atmosphere will move into Southern New England late Saturday Afternoon into Saturday Evening with the potential for isolated to scattered strong to severe thunderstorms. The headlines depict the current thinking. Key factors include:

1.) Amount of available instability since the impulse will move through past peak heating.
2.) Wind shear profiles are favorable which may compensate for lower instability if current timing in the late afternoon/early evening holds.
3.) If timing of the impulse is earlier than currently expected allowing better overlap of higher instability with strong wind shear and the impulse acting as a trigger in the atmosphere.
4.) Amount of available moisture in the atmosphere and the moisture return as we get toward later afternoon and evening.

SKYWARN Self-Activation will monitor the severe weather potential for Saturday late Afternoon and Evening. Another coordination message will be posted by 10 AM Saturday Morning. Below is the NWS Boston/Norton Area Forecast Discussion, Enhanced Hazardous Weather Outlook and SPC Day-2 Convective Outlook:

NWS Boston/Norton Area Forecast Discussion:

NWS Boston/Norton Enhanced Hazardous Weather Outlook:

SPC Day-2 Convective Outlook:

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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