Mesoscale Discussion 1142

Issued

Jul 2, 2021, 3:13 PM EDT (19:13 UTC)

Expired

Jul 2, 2021, 4:45 PM EDT

In force

92 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

5%

The Binghamton radar (KBGM), 79 km from the middle of the area, began a volume at 19:14 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.

141 
ACUS11 KWNS 021913
SWOMCD
SPC MCD 021913 
NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-022045-

Mesoscale Discussion 1142
NWS Storm Prediction Center Norman OK
0213 PM CDT Fri Jul 02 2021

Areas affected...Portions of Western New York...and Pennsylvania
into the Mid Atlantic

Concerning...Severe potential...Watch unlikely 

Valid 021913Z - 022045Z

Probability of Watch Issuance...5 percent

SUMMARY...Several clusters of thunderstorms may pose a low-end
severe risk for small hail or damaging wind gusts through this
afternoon. Limited storm organization suggests a watch is not
needed.

DISCUSSION...Beneath the center of a deepening upper low over the
Allegheny River Valley, several clusters of thunderstorms have
developed this afternoon across portions of western New York and
Pennsylvania. Partial clearing under the -17C 500 mb cold pocket has
allowed weak to moderate buoyancy (500-1000 J/kg of MUCAPE) to
develop supporting robust updrafts. Vertical shear remains quite
weak with regional VWPs sampling on average below 25 kts of
effective shear. Clusters of multi-cell storms will likely continue
through this afternoon with the potential for one or two damaging
wind gusts or small hail given steep mid-level lapse rates. 

Farther to the east, residual cloud cover along the cold front
moving east through the Mid Atlantic will slow surface heating and
limit diurnal destabilization. While better surface moisture exists
here along the coast, the eastward displacement from the plume of
steeper mid-level lapse rates should result in less available
buoyancy. This should be compensated somewhat by stronger effective
shear around 30 kts, though storm coverage should be lower. Isolated
damaging wind gusts will be possible with storms that develop before
moving completely offshore this evening.

..Lyons/Guyer.. 07/02/2021

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

ATTN...WFO...OKX...ALY...PHI...BGM...BUF...CTP...LWX...

LAT...LON   42987629 42607524 41647407 40377389 39887428 39287484
            39327549 40657782 41637895 42427932 43137863 43337804
            42987629

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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.