Severe Weather Coordination Message #2 – Sunday Evening 7/19/15-Eary Monday Morning 7/20/15 Severe Weather Potential

July 19, 2015 Rob Macedo Leave a comment

Hello to all..

..Potential exists for a significant severe weather outbreak across much of the NWS Taunton coverage area as well as adjoining coverage areas from mid to late Sunday Afternoon through early Monday Morning. The Storm Prediction Center (SPC) has expanded and upgraded the severe weather risk across Southern New England. Widespread pockets of damaging winds, hail, frequent lightning and heavy rainfall with urban and poor drainage flooding are the main threats..
..The situation could evolve from Isolated to Scattered Strong to Severe Thunderstorms during the early part of the Sunday severe weather potential time period and then potentially evolve into a Mesoscale Convective System (MCS) that will track over much of New England especially north of the Mass Pike but all of Southern New England has a potential risk for severe weather..
..Pictures and video of damage and conditions can be sent as a reply to this message, via the pictures email address of pics@nsradio.org and via the WX1BOX Facebook and Twitter feeds. Even pictures and video sent a day or several days after the event can be of use in providing information for the historical record of the event and for situational awareness and disaster intelligence purposes. Credit will be given to the Amateur Radio Operator/SKYWARN Spotters for the pictures and will be shared with emergency management, non-governmental organizations, media and posted on the WX1BOX Facebook page unless otherwise noted..
..SKYWARN Activation with Ops at NWS Taunton will commence no later than 400 PM and as early as 200 PM with operations extending into at least a portion of the overnight hours. ARES/RACES and Emergency Management groups should closely monitor the progress of today’s severe weather potential including the potential for severe weather to extend into the overnight hours..

The Storm Prediction Center (SPC) has upgraded and slid the severe weather risk further east. An enhanced risk for severe weather is forecast for Western Massachusetts, South-Central New Hampshire, South-Central Vermont and back into Eastern New York. Surrounding the enhanced risk area there is a slight risk for severe weather across Northern Connecticut, Central and Northeast Massachusetts. Surrounding the Slight risk area, there is a marginal risk for severe weather for the rest of Connecticut, Rhode Island and Southeast Massachusetts. NWS Taunton is in agreement with the assessment. These risk areas could change in configuration and be adjusted in category over the course of the day as thunderstorms begin to develop and their movement and organization is determined.

Intense heat and humidity will affect the region today. Initially, all levels of the atmosphere will be quite warm. This will initially “cap” convection from occurring. As we get into the timeframe as early as mid-late afternoon, cooling in the upper levels of the atmosphere will start taking place. With the intense heat and humidity in place and the cooling aloft occurring as a cold front approaches the region, wind shear will initially be modest but enough when combined with very high instability in place in the region to allow for isolated to scattered strong to severe thunderstorms in the highlighted risk areas for severe weather. The question then becomes whether this activity will organize into a complex of strong to severe thunderstorms known as a Mesoscale Convective System or MCS as wind shear will increase over time as we get into the early evening and overnight hours with intense instability remaining in place even after the time of peak heating.

Weather models even at short range and even with some of the high resolution models we have today can have trouble both with timing the severe weather and where the systems organize and track. Some computer models keep the activity just north of Southern New England while others track the activity into the northern half of Southern New England or even all the way to the Southern New England coastline. Some weather models get activity going as early as mid-afternoon while other computer models highlight the threat more towards evening.

Given this type of scenario, its imperative that situation be monitored very closely with the potential for a significant severe weather outbreak with widespread pockets of wind damage, hail, frequent lightning and heavy rainfall with urban and poor drainage flooding as the main threats. There is still the chance that activity is more isolated or scattered but given the potential for a more significant outbreak and that being a more likely scenario at this time, it needs to be considered from a preparedness perspective and if it does not occur, it serves as good practice for a situation that ends up being a more significant severe weather outbreak later in the season. Since activity could last into the late evening and a portion of the overnight hours, SKYWARN Spotters, Amateur Radio Operators and Emergency Management folks should have their NOAA All Hazards Radio set to alert them to a Severe Thunderstorm Warning for their area or use other such computer based systems to alert them to any impending severe weather for your specific local area during overnight hours.

Pictures and video of damage and conditions can be sent as a reply to this message, via the pictures email address of pics@nsradio.org and via the WX1BOX Facebook and Twitter feeds. Even pictures and video sent a day or several days after the event can be of use in providing information for the historical record of the event and for situational awareness and disaster intelligence purposes. Credit will be given to the Amateur Radio Operator/SKYWARN Spotters for the pictures and will be shared with emergency management, non-governmental organizations, media and posted on the WX1BOX Facebook page unless otherwise noted.

SKYWARN Activation with Ops at NWS Taunton will commence no later than 400 PM and as early as 200 PM with operations extending into at least a portion of the overnight hours. ARES/RACES and Emergency Management groups should closely monitor the progress of today’s severe weather potential including the potential for severe weather to extend into the overnight hours. As we move into operations mode, this will likely be the last coordination message for this severe weather potential but if the severe weather potential is a bit later this evening and time allows, an updated coordination message in some form could be posted by 600 PM. Below is the NWS Taunton Hazardous Weather Outlook, Special Weather Statement and SPC Day-1 Convective Outlook:

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

NWS Taunton Special Weather Statement:
http://kamala.cod.edu/ma/latest.wwus81.KBOX.html

SPC Day-1 Convective Outlook:
http://www.spc.noaa.gov/products/outlook/day1otlk.html

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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