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000
ACUS11 KWNS 220228
SWOMCD
SPC MCD 220228
ARZ000-LAZ000-TXZ000-OKZ000-220400-

Mesoscale Discussion 0542
NWS Storm Prediction Center Norman OK
0928 PM CDT Fri Apr 21 2017

Areas affected...Portions of southeast Oklahoma...North
Texas...southwest Arkansas

Concerning...Tornado Watch 155...

Valid 220228Z - 220400Z

The severe weather threat for Tornado Watch 155 continues.

SUMMARY...The threat for large hail, damaging gusts and possibly a
tornado continues over the remaining valid portions of the watch
area.

DISCUSSION...at 0230Z an east-west frontal boundary extended across
southern AR and southeast OK, transitioning into a cold front across
north-central TX southwest into the Permian Basin.  Several severe
storms were in progress from southeast OK into North TX, with a
history of large/very large hail and a brief tornado.

Latest objective analysis continues to reflect slowly increasing
CINH as a result of nocturnal cooling, likely contributing to the
isolated nature of storms along the front despite large-scale
frontal forcing. Ample effective shear and weak-moderate instability
remains in place to support supercells with large hail as the
primary threat.  A modestly strengthening low-level jet has resulted
in effective SRH of 200-250 m2/s2 ahead of the cold front, and at
least some risk for isolated damaging gusts and a tornado remains
for the next 1-2 hours as storms move into southwest AR and
northeast TX. Behind the cold front, a few stronger storms will pose
a risk for large hail as the dominant threat.

..Bunting.. 04/22/2017

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

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

LAT...LON   33749709 34359618 34879565 35079505 35109464 35139364
            34989301 34519294 33719343 33029396 32439465 32139512
            31979557 31859587 31709644 31429683 31209748 31199782
            31269807 31429861 31829867 32489871 33749709




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