Severe Storm Outlook Narrative (AC)
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ACUS11 KWNS 252157
SPC MCD 252157

Mesoscale Discussion 0553
NWS Storm Prediction Center Norman OK
0457 PM CDT Tue Apr 25 2017

Areas affected...Central/Northeast OK...Southeast KS...Far Western

Concerning...Severe potential...Watch likely

Valid 252157Z - 260000Z

Probability of Watch Issuance...95 percent

SUMMARY...Thunderstorm coverage will increase along the front over
the next hour or two with some severe storms likely. Primary severe
threats are very large hail and damaging wind gusts. A tornado or
two is also possible, particularly with any storms near the southern
end of the line around 00Z to 03Z.

DISCUSSION...Latest surface analysis placed a low over south-central
IA with a cold front extending southwestward from the low across
eastern KS and north-central OK to another low south of JWG. The
cold front then continues westward from this second low into the TX
panhandle. A dryline also extends from the second low
southward/southwestward into western north Texas. Moisture continues
to advect northward ahead of these boundaries with low 60 dewpoints
now into central OK with mid 50s extending into southeast KS/far
western MO. As the cold front continues southeastward and the subtle
lead shortwave trough progresses into the region (evidenced by
elevated echos/virga currently moving through western OK), forcing
for ascent, both on the meso-alpha and meso-beta scales, will
gradually increase with eventual convective initiation anticipated.
This convective initiation appears most likely along the cold front
from near Logan, Payne, and Noble counties in north-central OK
northeastward to around Elk and Wilson counties in southeast KS.
Once more persistent updrafts are established, the strongly sheared
airmass (0-6 km bulk shear in excess of 50 kt) will favor rotating
storms capable of large hail, some potentially greater than 2 inches
in diameter, damaging wind gusts, and potentially a tornado or two.

The relatively higher tornado threat is most likely towards the
southwestern end of any line of convection that develops where the
better moisture and instability exist. Additionally, the most likely
time frame for any tornadoes would be around 00Z to 03Z as the
low-level jet increases and the boundary layer is not overly hostile
to surface-based convection.

A watch will likely be needed in the next hour to cover this
anticipated severe threat.

..Mosier/Guyer.. 04/25/2017

...Please see for graphic product...


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