Mesoscale Discussion 1010

Issued

Jun 13, 2017, 2:25 PM EDT (18:25 UTC)

Expired

Jun 13, 2017, 5:00 PM EDT

In force

3 hr

Issued by

the Storm Prediction Center

Chance of a watch

40%

Counties Bristol County, MA, Hampden County, MA, Norfolk County, MA, Plymouth County, MA, Bergen County, NJ, Essex County, NJ, Passaic County, NJ, Sussex County, NJ, Bronx County, NY, Dutchess County, NY, Orange County, NY, Putnam County, NY, Rockland County, NY, Suffolk County, NY, Westchester County, NY, Bristol County, RI, Kent County, RI, Newport County, RI, Providence County, RI, Washington County, RI

The Brookhaven radar (KOKX), 64 km from the middle of the area, began a volume at 18:25 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

846 
ACUS11 KWNS 131825
SWOMCD
SPC MCD 131825 
MAZ000-RIZ000-CTZ000-NYZ000-NJZ000-132100-

Mesoscale Discussion 1010
NWS Storm Prediction Center Norman OK
0125 PM CDT Tue Jun 13 2017

Areas affected...Portions of southern New England...southeast
NY...northern NJ

Concerning...Severe potential...Watch possible 

Valid 131825Z - 132100Z

Probability of Watch Issuance...40 percent

SUMMARY...The area is being monitored for some severe thunderstorm
potential through the afternoon and into the evening. Uncertainty
exists regarding the anticipated severe coverage, though the
issuance of a Severe Thunderstorm Watch will be possible across
portions of the region.

DISCUSSION...Temperatures have warmed into the lower 90s from
northern NJ and southeast NY and across southern New England, while
the dewpoints have held in the middle/upper 60s. This is
contributing to 1500-2000 J/kg of MLCAPE with little capping.
Meanwhile, along the periphery of subtle midlevel speed maxima
crossing northern NY into adjacent New England, and along subtle
confluence axes farther south from northeast PA to southern New
England, ascent has been sufficient to support initial towering
cumulus and isolated thunderstorm development.

Thunderstorms will likely increase in number and intensity during
the next few hours as diurnal heating continues. A mix of weak
supercell structures, and loosely organized convective clusters, may
eventually evolve and spread eastward. This will be supported by
sufficient deep shear aided by 25-30 kt westerly winds around 4-5 km
above ground indicated by the Albany VAD wind profile. 

Present indications are that severe coverage could be lacking, owing
to the lack of stronger deep ascent/shear overlapping with the
moderate buoyancy. However, with at least isolated to widely
scattered severe hail/wind possible -- especially as convection
develops into southern New England -- Watch issuance will be
possible.

..Cohen/Hart.. 06/13/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...BOX...OKX...ALY...PHI...

LAT...LON   41207482 41977388 42427114 41827028 41457053 41097161
            40887261 40767437 41207482

Mesoscale Discussions in Connecticut, 2017Mesoscale Discussions in New York, 2017Mesoscale Discussions in Rhode Island, 2017Every mesoscale discussion in 2017

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.