Severe Weather Coordination Message #2 – Saturday 7/6/19 Severe Weather & Flood Potential

Hello to all…

..Isolated to Scattered Strong to Severe Thunderstorms likely Saturday Afternoon and Evening across much of Southern New England. Strong to damaging winds, heavy rainfall with urban to poor drainage flooding, and perhaps even flash flooding, and frequent lightning are the main threats with hail as a potential secondary threat..
..The Storm Prediction Center (SPC) has continued much of Southern New England in a marginal risk for severe weather with a slight risk of severe weather posted from portions of Essex County Massachusetts through portions of New Hampshire and Maine. The main timeframe for severe weather is anytime after 12 PM Saturday Afternoon through around 10 PM Saturday Evening..
..SKYWARN Activation with Ops at NWS Boston/Norton will commence by 12 PM Saturday through late Saturday Evening..
..A Heat Advisory is now in effect from 1-5 PM today for Western Essex and Central and Southeast Middlesex County Massachusetts for heat indices around 100 degrees. Anyone doing outdoor activities in the heat advisory area or across Southern New England should drink plenty of liquids and take precautions with the heat today..
..For Western Massachusetts Amateur Radio SKYWARN Spotters, the 146.940-Mount Tom Repeater PL: 127.3 Hz is back in service and SKYWARN Operations will be conducted on that repeater as required for Saturday..

A slow moving cold front will move through New England on Saturday after an intense day of heat and humidity for the region as temperatures will be in the upper 80s to lower 90s with dewpoint values in the low to mid-70s expected. Heat Advisories have been issued for portions of Northeast Massachusetts and everyone in Southern New England should drink plenty of liquids and take precautions with the heat today. The slow moving cold front with the intense heat and humidity in place will set the stage for isolated to scattered strong to severe thunderstorms across Southern New England as the front slowly moves through the region. The headlines depict the latest thinking which have not changed much since last night. Key factors on the severe weather and flooding potential include the following:

1.) Timing of the cold front through the region and the ability of the front to maximize the use of what is likely to be high instability levels.
2.) The strength of the winds aloft as the front swings through. The strongest winds are expected to be behind the cold front but there could be somewhat stronger winds in sync with the front. The more in sync those stronger winds are with the front, the greater the severe weather potential.
3.) Straight-line winds in the form of wet-microbursts are possible in isolated locations due to very moisture-laden storms making up for the lighter winds aloft. The extent of this will depend on the level of instability.
4.) Flooding is another concern in isolated to scattered locations particularly if cells are slow-moving and training over the same area as the environment will be very moist and tropical. This will also depend if areas affected are urbanized or poor drainage areas via either urbanization or differences in terrain.

SKYWARN Activation with Ops at NWS Boston/Norton will commence by 12 PM Saturday through late Saturday Evening. This will be the last coordination message as we shift into operations mode. 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:
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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