Severe Weather Coordination Message #1 – Monday Afternoon and Evening 7/3/23 & Tuesday Afternoon & Evening 7/4/23 Severe Weather/Flash Flood Potential

Hello to all…

..An active period of weather during a time of many outdoor activities for the July 4th Independence Day holiday in Southern New England..
..On Sunday through early Monday Morning, a swath of 2-4″ rainfall with isolated higher amounts occurred across Western, North-Central and Northeast Massachusetts and North-Central Connecticut with 0.50-2″ rainfall amounts across the remainder of Northern Connecticut and into parts of Norfolk, Middlesex and Suffolk Counties of Massachusetts. Rhode Island received the least rainfall and Southeast Massachusetts had between 0.10-1.2″ of rain with the higher amounts in Western Cape Cod..
..Isolated to Scattered Strong to Severe Thunderstorms are possible to likely particularly from the Mass Pike of Massachusetts South through Southeast Massachusetts, Rhode Island and Connecticut for later Monday Afternoon and Evening between 2-11 PM EDT. The Storm Prediction Center (SPC) has placed the area along and south of the Mass Pike in a marginal risk for severe weather but all areas of Southern New England should monitor this potential and thunderstorms with frequent lightning are possible in various locations across the region through not all areas may get thunderstorms on Monday..
..Isolated to scattered strong to severe thunderstorms are possible to likely again particularly from the Mass Pike of Massachusetts south through Southeast Massachusetts, Rhode Island and Connecticut for Tuesday Afternoon and evening between 12-8 PM EDT and SPC has placed this area in a marginal risk for severe weather but again all areas of Southern New England should monitor for thunderstorm and isolated severe weather potential though again not all locations will receive a thunderstorm..
..The primary threat with thunderstorms over the next two days is strong to damaging winds, hail, frequent lighting and heavy rainfall leading to urban and poor drainage flooding and flooding in areas that received heavy rainfall early Sunday Morning through Monday Morning..
..A Flood Watch is now in effect through Late Tuesday Night for Northern Connecticut, Northwest Providence County RI, Eastern Franklin, Eastern Hampshire, Eastern Hampden, Worcester, North-Central Middlesex, and Western Essex Counties for excessive rainfall causing flash flooding in areas that receive persistent heavy downpours and thunderstorms and in areas that receive these persistent heavy downpours and thunderstorms that also had heavy rainfall from Sunday 12 AM through Monday Morning..
..SKYWARN Self-Activation will monitor the severe weather potential for Monday Afternoon and Evening and Tuesday Afternoon and Evening..

An active period of weather over the next 48 hours for the July 4th Independence Day holiday. On Sunday through early Monday Morning, a swath of 2-4″ rainfall with isolated higher amounts occurred across Western, North-Central and Northeast Massachusetts and North-Central Connecticut with 0.50-2″ rainfall amounts across the remainder of Northern Connecticut and into parts of Norfolk, Middlesex and Suffolk Counties of Massachusetts. Rhode Island received the least rainfall and Southeast Massachusetts had between 0.10-1.2″ of rain with the higher amounts in Western Cape Cod. A detailed list of rainfall reports, flood reports and isolated severe thunderstorm wind damage can be seen here:

NWS Norton Amateur Radio and Non-Amateur Radio Spotter Reports Log:
https://wx1box.org/wp-content/uploads/2023/07/reports_7_2_23_7_3_23.pdf

NWS Norton Public Information Statement – Precipitation Reports:
https://wx1box.org/wp-content/uploads/2023/07/PNSBOX_7_3_23_Rainfall.pdf

Over the next two days, isolated to scattered strong to severe thunderstorms are possible to likely particularly in the areas along and south of the Mass Pike but all areas should monitor this potential. The headlines depict the current thinking. Key factors include:

1.) Amount of sunshine for heating and destabilization for Monday Afternoon and Evening. This is looking to be tracking to forecast with clearing over much of Southern New England as of 1130 AM this morning.
2.) Ability for thunderstorms to fire near or shortly after the time of peak heating today to allow them to become strong to severe and maximize instability given wind shear profiles that are marginal
3.) Flooding will be contingent on whether the same areas get hit hard repeatedly with heavy downpours or if the heavy downpours occur in areas that have received significant rainfall from the early Sunday Morning to Monday Morning period
4.) Tuesday’s timeframe and amount of coverage of strong to severe thunderstorms will hinge on lingering cloud cover from Monday convection to clear out to allow heating and how convective trends evolve for late Monday Afternoon and Evening
5.) Regardless of whether severe criteria in the form of damaging winds and large hail occurs, flooding from heavy rainfall is a concern along with frequent lightning which could affect outdoor events.
6.) Not all areas will see a thunderstorm over the next couple of days. Some locations will and could see significant impacts while other locations may not see any activity. Staying weather aware and monitoring future forecasts, watches and warnings if doing outdoor events will be key to insuring safety and to make the right decisions regarding continuing with outdoor events.

SKYWARN Self-Activation will monitor the severe weather potential for Monday Afternoon and Evening and Tuesday Afternoon and Evening. Another coordination message will be posted no later than 1130 AM Tuesday Morning and could be posted later Monday Evening depending on operations for the expected Monday Afternoon and Evening strong to severe thunderstorms. Below is the NWS Boston/Norton Flood Watch statement, Area Forecast, Discussion, Enhanced Hazardous Weather Outlook and SPC Day-1 Convective Outlook:

NWS Boston/Norton Flood Watch:
https://forecast.weather.gov/product.php?site=NWS&issuedby=BOX&product=FFA&format=CI&version=1&glossary=1&highlight=off

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 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

Respectfully Submitted,

Robert Macedo (KD1CY)
ARES SKYWARN Coordinator
Eastern Massachusetts ARES Section Emergency Coordinator
Home Phone #: (508) 994-1875
Home/Data #: (508) 997-4503
Email Address: rmacedo@rcn.com
https://ares.ema.arrl.org
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