Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 201841
SPC MCD 201840

Mesoscale Discussion 0526
NWS Storm Prediction Center Norman OK
0140 PM CDT Thu Apr 20 2017

Areas affected...Eastern Ohio...western Pennsylvania...far southwest
New York...northern West Virginia including the panhandles...and the
panhandle of Maryland

Concerning...Severe potential...Watch unlikely

Valid 201840Z - 201945Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated strong/locally severe storms will continue
developing this afternoon, with some gradual uptick in coverage of
risk possible.  While it appears at this time that risk should
remain sufficiently isolated to preclude WW issuance, we will
continue to monitor convective trends across this region.

DISCUSSION...Latest radar loop shows scattered showers and
thunderstorms -- including a few stronger/possibly severe storms --
ongoing across parts of western Pennsylvania at this time.  The
storms are occurring within a modestly unstable warm sector
(mixed-layer CAPE on the order of 500 to 1000 J/kg), within a zone
of ascent moving across the area per WV loop.

At this time, the spatial extent of severe risk is generally limited
to areas west of the Appalachian crest, and into the eastern West
Virginia/Maryland panhandles -- i.e. within the axis of greater
instability.  Meanwhile, implied subsidence is indicated across much
of eastern Ohio given trends in the CU field as observed in visible
satellite imagery.  However, as the next wave of ascent overspreads
Ohio with time, new convective development into eastern Ohio could
occur.  With that said, short-term indications are that WW issuance
should remain unnecessary, with severe risk limited to isolated
stronger storms/storm clusters.

..Goss/Thompson.. 04/20/2017

...Please see for graphic product...


LAT...LON   40068218 40598203 41788189 42147997 42137880 40597773
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