Severe Storm Outlook Narrative (AC)
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039
ACUS11 KWNS 201951
SWOMCD
SPC MCD 201950
PAZ000-WVZ000-OHZ000-202215-

Mesoscale Discussion 1364
NWS Storm Prediction Center Norman OK
0250 PM CDT Thu Jul 20 2017

Areas affected...Eastern/southern OH...western/central PA...northern
WV

Concerning...Severe potential...Watch unlikely

Valid 201950Z - 202215Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated damaging-wind potential could accompany
thunderstorms moving across portions of the middle and upper Ohio
Valley region to the central Appalachians and vicinity into the
early evening hours. Watch issuance is presently unlikely.

DISCUSSION...Thunderstorm development continues along a diffuse cold
front from northwest PA through north-central OH. Additional storm
development may also focus along the northern and eastern periphery
of a residual MCV presently moving across southwest OH. MCV-related
ascent is being augmented by differential-heating-induced baroclinic
circulations along fringes of multi-layered cloud decks surrounding
the MCV. The air mass south of the front and ahead of the MCV has
become moderately unstable, owing to surface temperatures having
warmed through the 80s amid dewpoints in the upper 60s to around
70F. The most intense storms may produce locally damaging wind
gusts -- aided by slightly enhanced deep shear (around 20-40 kt of
effective shear).

However, stronger deep shear resides north of this region, which
should limit overall convective organization. Moreover, poor
mid-level lapse rates, veered low-level flow ahead of the front
limiting frontal convergence, and modest background low-level flow
strength should prevent a more substantial severe risk from
occurring.

..Cohen/Coniglio/Hart.. 07/20/2017

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

ATTN...WFO...CTP...PBZ...RLX...CLE...ILN...

LAT...LON   38778280 39978264 40698240 41018144 41048067 41197968
            41607839 41327776 40857789 39657963 38878172 38698229
            38778280




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