Severe Storm Outlook Narrative (AC)
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000
ACUS01 KWNS 291249
SWODY1
SPC AC 291248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Wed Mar 29 2017

Valid 291300Z - 301200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN
PORTIONS OF THE SOUTHERN PLAINS INTO THE MIDDLE AND LOWER
MISSISSIPPI VALLEY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
PORTIONS OF THE SOUTHERN PLAINS THROUGH THE MIDDLE AND LOWER
MISSISSIPPI VALLEY...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK AREA...

...SUMMARY...
Severe thunderstorms are expected later today into tonight from
parts of east Texas, eastern Oklahoma, and southeast Kansas into the
lower and middle Mississippi Valley. Very large hail, tornadoes (a
couple of which could be strong) and damaging wind are all possible.

...East Texas and Oklahoma, southeast Kansas into the middle and
lower Mississippi Valley areas...

Ongoing line of storms moving through eastern OK, extreme western AR
and southeast TX should continue a gradual diminishing trend as it
advances east this morning, though an isolated strong wind gust or
two cannot be ruled out over southeast TX. The expansive convective
debris will delay destabilization until at least early afternoon
when pockets of diabatic warming and northward advection of modified
continental polar air should contribute to some boundary-layer
recovery and a corridor of 500-1500 J/kg MLCAPE from eastern
portions of the Southern Plains to the lower to middle MS valley.
Initial surface low has consolidated over eastern OK this morning in
association with a lead northeastward-ejecting shortwave trough.
This feature will move very slowly northeast into southeast KS
during the day while weaker secondary cyclogenesis is possible
farther south across AR during the evening as another lobe of
vorticity rotates through the base of the upper trough accompanied
by a strengthening secondary branch of the low-level jet.

Current indication is that additional storms will likely develop
from southeast KS through eastern OK and eastern TX this afternoon
in corridor of stronger destabilization and within the evolving
pre-frontal confluent flow regime. This activity will subsequently
move east into southern MO, AR and LA. Mid-level jet rotating
through the base of the upper trough will contribute to favorable
vertical shear profiles for supercells, and low-level hodographs
will support potential for a few low-level mesocyclones and
tornadoes (a couple of which could be strong) especially as storms
move east into AR and southern MO where strengthening low-level jet
will be maximized during the late afternoon into the evening.
Initially discrete modes will promote a risk for very large hail and
a few tornadoes, but tendency will be for storms to consolidate into
lines by mid-late evening which suggest primary threat should
eventually transition to damaging wind overnight. Due to the
stabilizing effects of morning convection which will delay and
potentially limit boundary layer recovery, will not introduce a
moderate risk at this time but continue to evaluate during the next
update.

..Dial/Grams.. 03/29/2017

$$



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