Remnants of Ida Coordination Message #2 – Late Wednesday Night 9/1/21-Thursday Afternoon 9/2/21 Flash Flood & Severe Weather Potential

Hello to all…

..The remnants of Ida will bring the potential threat of widespread heavy rainfall and flash flooding as the primary concern but also the secondary concern of strong to damaging winds across the region with the threat for an isolated weak tornado or isolated pockets of enhanced wind damage in severe thunderstorms in Southeast Coastal New England..
..A Flash Flood Watch remains in effect for the entire NWS Boston/Norton coverage area for widespread rainfall of 2-6″ with isolated amounts higher amounts in parts of the flash flood watch area. This rainfall forecasted if it occurs in a short period of time will result in widespread pockets of urban and poor drainage flooding with small river and stream flooding likely. It is noted that the Weather Prediction Center (WPC) has placed much of Southern New England in a moderate to high risk of excessive rainfall..
..The Storm Prediction Center (SPC) has placed Southeast Coastal Massachusetts and Rhode Island in a marginal risk for severe weather with strong to damaging winds and an isolated weak tornado as the main threats..
..Strong general wind gusts of 30-40 MPH inland, and 35-45 MPH with isolated higher gusts at the coast are possible depending on the ability of those winds to reach the surface as well as the track and intensity of the remnants of Ida as it taps into non-tropical energy as it moves through the region. These wind gusts coupled with saturated ground and additional rainfall may cause somewhat higher wind damage potential than normal due to the wet conditions though this remains a secondary concern compared to the rainfall and flood threat..
..SKYWARN Self-Activation with Amateur Radio Call-Up Nets Likely overnight Wednesday Night into Thursday Afternoon for the main threats of flash flooding and measured rainfall reports but the secondary threat of strong to damaging winds and isolated severe thunderstorms with an isolated weak tornado..

The remnants of Ida will impact the weather across Southern New England significantly late Wednesday Night through Thursday Afternoon. The headlines depict the current thinking and potential. Key factors include:

1.) The axis of heaviest rain could shift further north and west or shift a little south and east in future updates but a widespread heavy rainfall is expected regionwide. Flash Flooding is the primary concern from this storm event. Where an enhanced area of rainfall of between 4-7″ sets up could be around the Mass Pike area, areas just north of there or areas south of there across Connecticut, Rhode Island and Southeast Massachusetts and small track changes in the remnants will determine where this sets up.
2.) Some weather models are depicting strong to damaging wind gusts with the remnants Ida as it taps into non-tropical energy. The key will be weather these strong winds materialize and whether they can reach the surface. This will bear monitoring as a secondary concern as the wet ground, additional rainfall coupled with strong wind gusts could lead to higher impacts in terms of wind damage if those wind gusts were to materialize. Currently wind gusts of 30-40 MPH inland and 35-45 MPH with isolated higher gusts at the coast seem like the most probable scenario.
3.) There is the potential for thunderstorms to enhance the wind gusts in Southeast coastal New England along with the potential for isolated weak tornadoes. This is also a secondary concern that bears watching and will depend on the track of the remnants of Ida and if they track near or over Southern New England allowing Southeast Coastal New England to get into more of the warm sector.

SKYWARN Self-Activation with Amateur Radio Call-Up Nets Likely overnight Wednesday Night into Thursday Afternoon for the main threats of flash flooding and measured rainfall reports but the secondary threat of strong to damaging winds and isolated severe thunderstorms with an isolated weak tornado. This will be the last coordination message as we move into operations mode. Below is the NWS Boston/Norton Flash Flood Watch Statement, Area Forecast Discussion, Enhanced Hazardous Weather Outlook, Rainfall Forecast Map, WPC Excessive Rainfall 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 Flood Watch Statement:
https://kamala.cod.edu/ma/latest.wgus61.KBOX.html

NWS Boston/Norton Enhanced Hazardous Weather Outlook:
https://www.weather.gov/box/ehwo

NWS Boston/Norton Rainfall Map:
http://wx1box.org/wp-content/uploads/2021/08/StormTotalQPF_SFC4.png

WPC Excessive Rainfall Outlook:
https://www.wpc.ncep.noaa.gov/qpf/ero.php?opt=curr&day=1

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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