Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 231825
SWOMCD
SPC MCD 231824
SCZ000-GAZ000-232100-

Mesoscale Discussion 0551
NWS Storm Prediction Center Norman OK
0124 PM CDT Sun Apr 23 2017

Areas affected...Portions of SC and far east-central GA

Concerning...Severe potential...Watch unlikely

Valid 231824Z - 232100Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated strong/gusty wind and perhaps brief tornado
threat may exist this afternoon with thunderstorms developing along
a front. Watch issuance is unlikely in the short term.

DISCUSSION...A stalled front is draped east-west across SC into far
east-central GA as of 18Z per recent visible satellite imagery and
surface observations. Although large-scale ascent associated with an
upper low over TN remains displaced to the west, low-level
convergence along the front has proven sufficient for the initiation
of isolated showers and thunderstorms in SC over the past hour or
so. The airmass along and south of the boundary is weakly unstable
(MLCAPE up to 750 J/kg), with surface temperatures generally in the
low to mid 80s and dewpoints in the low to mid 60s. Mid-level lapse
rates remain poor across this region, around 6 C/km.

Both low and mid-level flow are generally modest (30 kt or less),
although strongly backed winds in the 0-1 km layer along and just
north of the front are contributing to 0-1 km SRH around 200-250
m2/s2 per recent VWPs from KCAE. A veering wind profile with height
is supporting 30-35 kt of effective bulk shear, locally higher right
along the front. The combination of weak instability and shear along
may allow for some updraft organization with the strongest storms,
and isolated instances of strong/gusty winds may occur. In addition,
a brief tornado cannot be ruled out with any storm which crosses the
boundary and encounters greater effective SRH along/just north of
the front. The overall severe weather threat is expected to remain
isolated through the afternoon, and watch issuance is unlikely.

..Gleason/Weiss.. 04/23/2017

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

ATTN...WFO...ILM...CHS...CAE...GSP...FFC...

LAT...LON   33068164 33438280 33578299 33988307 34268273 34168169
            34088062 33987988 33817931 33627889 33277902 32987932
            32858029 33068164



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