Severe Storm Outlook Narrative (AC)
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000
ACUS02 KWNS 200559
SWODY2
SPC AC 200558

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Fri Apr 20 2018

Valid 211200Z - 221200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM CENTRAL TX
INTO WESTERN/SOUTHWESTERN LA...

...SUMMARY...
Scattered strong/severe thunderstorms are possible across portions
of Texas into southern Louisiana Saturday.

...Southern Plains...
Fairly deep upper trough will move across the central/southern
Plains on Saturday, accompanied by enhanced mid-level flow through
its southern periphery. An attendant surface low will gradually
weaken/fill as it progresses across central TX and a cold front will
move across the majority of the southern Plains in its wake.

A confined warm sector is anticipated ahead of this low,
characterized by dewpoints in the mid 60s. Northern extent of the
warm sector will be limited by both the more southerly track of the
surface low and by widespread warm-advection showers and
thunderstorms across OK and north/northeast TX. A few of these
elevated storms may produce small hail, but the severe threat is
currently anticipated to be fairly limited.

Within the limited warm sector, expansive cloudiness will likely
temper heating throughout much of the morning through mid-afternoon.
Thereafter, as the warm conveyor shifts eastward, some clearing just
ahead of the cold front is possible. While some mixing will likely
occur if this clearing is realized, enough low-level moisture would
still be in place to support isolated thunderstorm development along
the cold front amidst the modestly unstable environment.  With the
warm conveyor displaced east, low-level flow (i.e. 850 mb and below)
will likely have weakened but enhanced mid-level flow will still
support moderate to strong bulk shear. As a result, a few strong to
severe storms are possible from north-central into central TX as the
cold front pushes through. This severe potential merits low severe
probabilities (i.e. 5%) but uncertainty regarding numerous factors
including the actual track of the surface low, warm front position,
and extent of the clearing ahead of the cold front precludes higher
probabilities with this forecast.

..Mosier.. 04/20/2018

$$



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