Severe Weather Coordination Message #3 – Saturday 6/29/19-Sunday 6/30/19 Severe Weather Potential

Hello to all…

..Isolated to Scattered strong to severe thunderstorms remain possible to likely Saturday Afternoon and Evening across much of Southern New England. Strong to Damaging winds, hail, frequent lightning and heavy rainfall with the potential for urban and poor drainage flooding are the main threats. Timeframe is any time between 12-8 PM today..
..The Storm Prediction Center (SPC) has continued most of Southern New England in a slight risk for severe weather and Cape Cod and the Islands in a marginal risk for severe weather for Saturday..
..There is another chance for severe weather for Sunday with risks similar to today though the potential for hail on Sunday could be higher given a cold pool of air aloft in the region. We will get into some details in this message with more details in the Saturday Evening coordination message..
..SKYWARN Activation with Ops at NWS Boston/Norton will commence by 11-1130 AM Saturday Morning. SKYWARN Activation with Ops at NWS Boston/Norton is possible Sunday for the severe weather potential..

..For Western Massachusetts Amateur Radio SKYWARN Spotters, the 146.94-Mount Tom Repeater which is the primary repeater for this area is down. For SKYWARN Operations in Western Massachusetts, please use the 147.000-Granville Repeater PL 127.3 Hz. If that is not reachable from your location, please use the 146.79-Vernon, CT Repeater PL 82.5..

It will potentially be an active weekend for severe weather across Southern New England. An initial round of thunderstorms moved through portions of Central and Eastern Massachusetts this morning. Satellite imagery shows some clearing behind this activity particularly in Connecticut and Southeast New York which will spread through the region later this morning into early afternoon. This is expected to allow the destabilization required for isolated to scattered strong to severe thunderstorms across the slight risk area as depicted by SPC.

For Saturday, the headlines depict the current severe weather potential well. Key factors for Saturday’s severe weather potential and extent of strong to severe thunderstorm coverage remain the following:

1.) Amount of cloud cover over the area as that will determine destabilization and level of instability for the region.
2.) Timing of the cold front through the region.
3.) Favorable factors for severe weather potential include sufficient wind shear profiles and good cooling of the atmosphere aloft along with a strong triggering mechanism with the cold front.

As we look at Sunday, wind shear profiles will become less favorable in the region but cooling aloft will be more significant and that will increase instability parameters. This will potentially allow for another round of isolated to scattered strong to severe thunderstorms. The wind threat for Sunday maybe somewhat reduced but the hail threat will be higher and the cold air aloft may also compensate to a degree for the lack of wind shear. The timing of this activity is still in flux but activity could be in the mid to late morning through early evening hours.

SKYWARN Activation with Ops at NWS Boston/Norton will commence between 11-1130 AM today. SKYWARN Activation with Ops at NWS Boston/Norton are possible again on Sunday. This will be the last coordination message for the Saturday severe weather potential as we move into operations mode. Another coordination message will be posted by 1030 PM Saturday Evening on the Sunday severe weather potential. Below is the NWS Boston/Norton Hazardous Weather Outlook, Enhanced Hazardous Weather Outlook and SPC Day-1 Convective Outlook:

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

NWS Boston/Norton Experimental 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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