Severe Weather & Heat Coordination Message #2 – Extreme Heat Sunday 6/22/25-Tuesday 6/24/25 & Severe Weather Potential Sunday 6/22/25 Early AM thru Evening

Hello to all…

**This coordination message is a small update to the morning message with some updates from SPC on the severe weather potential from their latest Day-2 Outlook and the latest NWS Boston/Norton Afternoon Area Forecast Discussion. It remains a lower confidence forecast on the severe weather potential.**

..After Friday’s strong to damaging wind event, attention turns to extreme heat Sunday to Tuesday and severe weather potential for overnight Saturday to Sunday Morning and possibly later Sunday Afternoon and Evening..
..Extreme heat is expected to setup over the region Sunday through Tuesday. The highest heat days are expected to be Monday and Tuesday. Sunday could have high heat potential as well but that will also be contingent on how a Mesoscale Convective System or (MCS) tracks and whether it affects Southern New England and lingers during the morning or tracks north of the region. This MCS will also have an impact on any severe weather potential that would occur during the overnight hours into Sunday Morning and any later Sunday Afternoon and Evening potential..
..The Storm Prediction Center (SPC) has continued portions of Western Massachusetts from roughly the CT Valley west in a marginal risk for severe weather today during the overnight period of the Day-1 Convective Outlook and has placed all of Southern New England in a marginal risk for severe weather for Sunday. The Sunday potential remains dependent on how the MCS tracks and whether its over or north of the region and how/if the atmosphere becomes favorable for severe weather later Sunday Afternoon. SPC has hinted depending on the MCS track and how things evolve that an upgrade to the marginal risk could occur for either Southern New England or the Mid-Atlantic..
..Confidence in severe weather potential overnight through Sunday remains lower than normal for this timeframe and there could be significant short term changes to the potential ranging from a very potent event to little or no activity. Trends will be monitored on this potential..
..Timeframe for severe weather potential would be from around 3 AM-11 AM Sunday Morning if the MCS tracks over the region and then mid-Sunday Afternoon to early evening for a possible second round of severe weather potential. Strong to damaging winds, hail, frequent lightning and heavy downpours leading to urban and poor drainage flooding are the main threats. Given the overnight timing, please have a way to alert yourself to severe weather during nocturnal hours if warnings are issued for your local area..
..An Extreme Heat Warning remains in effect from 11 AM Sunday to 8 PM Tuesday Evening for the entire NWS Norton Coverage area except for Cape Cod and the Islands and the East slopes of the Berkshires for heat indices of up to 110 degrees expected. A Heat Advisory remains in effect from 11 AM Sunday to 8 PM Tuesday for Western Franklin, Western Hampshire and Western Hampden Counties for heat indices up to 100 degrees expected. Use caution with any outdoor activities, drink plenty of liquids and take frequent breaks from the heat in Air Conditioning when possible..
..SKYWARN Self-Activation with Amateur Radio Call-Up Nets are possible overnight tonight to late Sunday Morning and possibly again Sunday Afternoon and Evening. Pictures and videos of storm damage, hail, and flooding can be sent as a reply to this email, via our WX1BOX Facebook, X and Bluesky feeds or to the email address pics@nsradio.org with credit given to the spotter unless otherwise indicated..

With fully leaved out trees and wind gusts of 40-50 MPH and isolated higher gusts, pockets of tree and wire damage occurred particularly in interior Massachusetts, Rhode Island and Northeast Connecticut. Any pictures/videos etc. from Friday’s high wind event are still welcome. Below is a summary on the wind gusts and wind damage reports received:

WX1BOX Amateur Radio Log:
https://wx1box.org/wp-content/uploads/2025/06/reports_6_20_25.pdf

The headlines depict the current thinking on the Extreme Heat Warning and Heat Advisory. While Sunday’s high temperature profile will be contingent on a severe weather complex known as a MCS as highlighted in the headlines, Monday and Tuesday are a high confidence on intense heat and humidity so use caution if doing any strenuous activities outdoors or in non-Air Conditioned environments, stay cool and drink plenty of liquids.

Turning our attention to the severe weather potential, this remains a lower than normal confidence for an event that could occur in roughly 12-24 hours. The setup which could feature a MCS has varying model solutions from no impact and it staying far to the north to a very potent event affecting Southern New England. The MCS activity will be during the overnight hours into Sunday Morning further complicating any preparedness. Having a means to be alerted to any Severe Thunderstorm or other warnings during the overnight via NOAA Weather Radio Alert and WEA is suggested for this timeframe. If no warnings are issued, alerts won’t occur and if there is a warning posted you can prepare as needed for the severe weather potential.

Any activity Sunday Afternoon and Evening will be predicated on the MCS track. A MCS track over the area could result in little to no activity later Sunday and may also reduce temperatures a bit due to lingering clouds and shower and thunderstorm activity. If the MCS stays to the north, then there could be severe weather potential later Sunday Afternoon and Evening but it would need a trigger to break a cap despite extreme instability from intense heating. This is a bit of a “nowcasting” situation that will be updated.

The key factors in the severe weather potential and when it occurs;
1.) The track of the MCS which will determine a round of overnight into mid to late Sunday Morning activity and how it affects later day activity.
2.) The intensity of the MCS as it brings what is known as an Elevated Mixed Layer or EML that brings in extreme instability and there will be strong wind shear present.
3.) Later day activity is dependent on the MCS track and if any thunderstorm activity can break the Cap and take advantage of extreme instability presuming intense heating and destabilization depending on the track of the MCS and if the track is over the region, how quickly it clears out.

SKYWARN Self-Activation with Amateur Radio Call-Up Nets are possible overnight tonight to early Sunday Morning and possibly again Sunday Afternoon and Evening. Pictures and videos of storm damage, hail, and flooding can be sent as a reply to this email, via our WX1BOX Facebook, X and Bluesky feeds or to the email address pics@nsradio.org with credit given to the spotter unless otherwise indicated. The next coordination message will be posted by 9 AM Sunday Morning. Below is the NWS Boston/Norton Area Forecast Discussion, Enhanced Hazardous Weather Outlook and SPC Day-1 and Day-2 Convective Outlook:

NWS Boston/Norton Area Forecast Discussion:
https://forecast.weather.gov/product.php?site=NWS&issuedby=BOX&product=AFD&format=CI&version=1&glossary=1&highlight=off

NWS Boston/Norton Extreme Heat Warning/Heat Advisory Statement:
https://forecast.weather.gov/product.php?site=NWS&issuedby=BOX&product=NPW&format=CI&version=1&glossary=1&highlight=off

NWS Boston/Norton Enhanced Hazardous Weather Outlook:
https://www.weather.gov/erh/ghwo?wfo=box

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/archive/2025/day2otlk_20250621_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)
Email Address: rmacedo@rcn.com
https://ares.ema.arrl.org
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