Storm/Severe Weather Coordination Message #2 – Tuesday Afternoon/Evening 4/21/20 Severe Weather and Strong Wind Potential

Hello to all..

..A Strong Cold front will have the potential to bring Isolated to Scattered Strong to Severe Thunderstorms with strong to damaging winds and hail as the main threats during Tuesday Afternoon and Early Evening and strong to damaging post frontal winds Tuesday Evening and to a lesser extent Wednesday Morning. The Storm Prediction Center (SPC) has placed much of Southern New England in a marginal risk for severe weather with Central and Southern Connecticut and Southwest Rhode Island in a slight risk for severe weather..
..A Wind Advisory is now in effect for Northeast Connecticut, Rhode Island, Eastern Essex, Southeast Middlesex, Suffolk, Norfolk, Bristol and Plymouth Counties of Massachusetts from 2-7 PM Tuesday and for Cape Cod and the Islands from 2-9 PM for sustained winds of 15-25 MPH with gusts to 50 MPH. The Wind Advisory for Western and Central Massachusetts and Northwest and North-Central Connecticut is cancelled but wind gusts to around 40 MPH with isolated higher gusts are possible. These winds will have the potential to cause isolated to scattered pockets of tree and wire damage and isolated to scattered power outages..
..SKYWARN Self-Activation with Amateur Radio Call-Up nets will monitor the strong to severe thunderstorm potential and strong to damaging wind potential Tuesday Afternoon into Tuesday Night..

A strong cold front will move across the region on Tuesday and bring unusually cold air into the region. Ahead of the cold front is the potential for strong to severe thunderstorms and then along and behind the front is the potential for strong to damaging winds. The headlines depict the current thinking. Key factors include:

1.) Surface based instability is limited, however, there will be a significant cold pool of air aloft and very strong winds aloft which will likely compensate for the lack of surface instability allowing for strong to severe thunderstorm development. There have already been numerous reports of small hail in Southern Connecticut with some morning shower and thunderstorm activity and we could see some of this activity late this morning into early this afternoon before the main cold front and possible squall line swings through the region.
2.) If there is greater surface instability, that would increase the coverage of strong to severe thunderstorms given other favorable parameters.
3.) Strong winds behind the cold front will be near or just above advisory levels with the greatest risk of strong wind gusts and will last into the first half of Wednesday and cause isolated pockets of wind damage. The strongest winds will be Tuesday Afternoon into early evening with the strongest winds in Northeast Connecticut, Rhode Island and East Coastal and Southeastern Massachusetts. The Wind Advisory has been dropped in Western and Central Massachusetts and Northwest and North-Central Connecticut but wind gusts of 40 MPH with isolated higher wind gusts are possible there for this afternoon and tonight. As we move into Wednesday, there will be wind gusts of around 40 MPH particularly in the first half of the day.

SKYWARN Self-Activation with Amateur Radio Call-Up nets will monitor the strong to severe thunderstorm potential and strong to damaging wind potential Tuesday Afternoon into early Wednesday Morning. This will be the last coordination message as we shift into operations mode. Below is the NWS Boston/Norton Wind Advisory, Hazardous Weather Outlook, Enhanced Hazardous Weather Outlook and SPC Day-1 Convective Outlook:

NWS Boston/Norton Wind Advisory Statement:
https://kamala.cod.edu/ma/latest.wwus71.KBOX.html

NWS Boston/Norton Hazardous Weather Outlook:
https://kamala.cod.edu/ma/latest.flus41.KBOX.html

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

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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