Severe Weather Coordination Message #4 – Monday Evening 7/14/14-Wednesday 7/16/14 – Severe Weather Potential

July 15, 2014 Rob Macedo Leave a comment

Hello to all..

..Threat overnight is more for heavy rainfall and flash flooding with a low risk for an isolated strong to severe thunderstorm with strong winds possible..
..The Storm Prediction Center (SPC) has upgraded portions of Western Massachusetts and Western Connecticut from the Connecticut River Valley west in a slight risk for severe weather with 5% severe weather probabilities for the rest of Southern New England except for Cape Cod and the Islands for Tuesday. The highest risk with thunderstorms at this time is heavy rainfall and flash flooding of urban and poor drainage areas and possibly smaller rivers and streams, however, strong to Damaging winds, and hail are also threats with an isolated weak tornado also possible depending on the timing of the front and amount of cloud cover over the area for Tuesday..
..A Flash Flood Watch is now in effect from Monday Evening through Wednesday afternoon for all of the NWS Taunton coverage area of Massachusetts, Rhode Island and Northern Connecticut. A Flash Flood Watch is now in effect for Southern New Hampshire from Tuesday Morning through Wednesday Afternoon..
..SKYWARN Activation with Ops at NWS Taunton were executed for a few hours Monday Evening. SKYWARN Self-Activation will monitor flash flood potential overnight. SKYWARN Activation with Ops at NWS Taunton are likely some time between 1-4 PM Tuesday Afternoon lasting through late Tuesday Evening. SKYWARN Activation with Ops at NWS Taunton are possible Wednesday Morning for flash flood potential especially in Eastern New England..

On Monday, the severe weather threat stayed south of the NWS Taunton coverage area. Heavy downpours during the evening commute caused some minor street flooding issues in the Boston area. Overnight, there is the potential for heavier thunderstorms with the main threat of flash flooding to potentially effect portions of Eastern Massachusetts and Rhode Island. An isolated strong to severe thunderstorm with strong winds is possible but is a low risk. Given the timeframe for this may be as late as around midnight and the overnight hours, SKYWARN Self-Activation will be utilized to monitor the activity overnight.

As we move into Tuesday, the slow moving cold front will continue to approach Eastern New York and New England. There will continue to be warm and humid conditions over the area. The extent of the severe weather potential will be determined by the following:

1.) Amount of cloud cover over the area and any overnight showers and thunderstorms that may linger into Tuesday Morning.
2.) Position of the cold front and its forcing mechanism and the timing of the front over the area.

If there is sufficient clearing for destabilization and the front is close enough for forcing, that would mean a greater potential for severe weather in the region. If cloud cover remains over the area or the forcing from the cold front does not come in around or near peak heating, then the severe weather threat will be more muted. The Storm Prediction Center (SPC) has upgraded portions of Western Massachusetts and Western Connecticut from the Connecticut River Valley west in a slight risk for severe weather with 5% severe weather probabilities for the rest of Southern New England except for Cape Cod and the Islands for Tuesday.

Regardless of these two factors, thunderstorms with the potential for heavy rainfall and flash flooding of poor drainage and urban areas and smaller rivers and streams are the highest potential weather hazard in localized areas over the NWS Taunton coverage area. The Flash Flood Watch has been expanded to include the entire NWS Taunton coverage area except for Cape Cod and the Islands through Wednesday Afternoon. The start time of the Flash Flood Watch for Southern New Hampshire is Tuesday Morning lasting through Wednesday Afternoon. Heavy rainfall of 1-3″ with localized higher amounts where thunderstorms back build or train over the same area are possible. The flash flood threat will linger through early Wednesday Afternoon particularly over Eastern New England as the slow moving cold front finally pushes through Southern New England. Any severe weather potential Tuesday Afternoon through Evening will evolve into more of a heavy rainfall threat overnight Tuesday into Wednesday.

The next coordination message will be issued by 1100 AM Tuesday Morning. Below is the NWS Taunton Hazardous Weather Outlook, NWS Taunton Flash Flood Watch Statement and SPC’s Day-1 and Day-2 Convective Outlooks:

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

NWS Taunton Flash Flood Watch Statement:
http://kamala.cod.edu/ma/latest.wgus61.KBOX.html

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

SPC Day-2 Convective Outlook:
http://www.spc.noaa.gov/products/outlook/day2otlk.html