Severe Weather Coordination Message #1 – Saturday July 8th, 2017 Severe Weather Potential

July 8, 2017 Rob Macedo Leave a comment

Hello to all…

..Isolated to scattered strong to severe thunderstorms are possible to likely Saturday, possibly as early as late Saturday Morning and extending through the late afternoon and early evening hours Saturday. Strong to damaging winds, large hail, frequent lightning and heavy rainfall with urban and poor drainage flooding are the main threats. The Storm Prediction Center (SPC) has placed much of Southern New England in a marginal risk for severe weather for Saturday..
..SKYWARN Activation with Ops at NWS Taunton is likely Saturday..

On Friday, significant flash flooding affected portions of Cape Cod from Falmouth and Sandwich through Barnstable, Dennis and Yarmouth and to a lesser extent on Outer Cape Cod. Storm report information and a few flooding photos can be seen at the following links:

WX1BOX Storm Report Log:
http://beta.wx1box.org/local/reports_7_7_17.txt

NWS Taunton Local Storm Report:
http://kamala.cod.edu/ma/latest.nwus51.KBOX.html

NWS Taunton Public Information Statement – Rainfall Reports:
http://kamala.cod.edu/ma/latest.nous41.KBOX.html

WX1BOX Facebook Photo Album:
https://www.facebook.com/pg/wx1box/photos/?tab=album&album_id=1622155554485123

On Saturday, there is a risk for at least a few isolated to scattered strong to severe thunderstorms across Southern New England as a cold front sweeps through the region. Some high-resolution models are also hinting at a more widespread severe weather event in Southern New England but there is not enough consensus in the models to determine if that will be the likely scenario. There will be sufficiently strong winds aloft to support the severe weather potential. The headlines of the coordination message capture the current situation well. The key items that will determine the extent and coverage of strong to severe thunderstorms are as follows:

1.) A pre-frontal trough and its potential passage in the morning hours and whether this brings cloud cover over the region that doesn’t allow the atmosphere to destabilize when the cold front passes through the region presuming the pre-frontal trough timing remains in the morning.
2.) Presuming a morning pre-frontal trough passage and then a cold front in the afternoon, if the atmosphere can destabilize, whether too much mid-level dry air after the pre-frontal trough passage keeps coverage of any strong to severe thunderstorms limited or causes a total lack of strong to severe thunderstorm development.
3.) Timing of the actual cold front and whether it comes through in the mid to late afternoon as currently anticipated.

SKYWARN Activation with Ops at NWS Taunton is likely Saturday. Another coordination message will be posted by 1000 AM Saturday Morning. Below is the SPC Day-2 Convective Outlook and the NWS Taunton Hazardous Weather Outlook and Experimental Enhanced Hazardous Weather Outlook:

SPC Day-2 Convective Outlook:
http://www.spc.noaa.gov/products/outlook/archive/2017/day2otlk_20170707_1730.html

NWS Taunton Hazardous Weather Outlook:

http://kamala.cod.edu/ma/latest.flus41.KBOX.html

NWS Taunton Experimental Enhanced Hazardous Weather Outlook:
https://www.weather.gov/box/ehwo

Respectfully Submitted,

Robert Macedo (KD1CY)
ARES SKYWARN Coordinator
Eastern Massachusetts ARES Assistant 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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