Severe Storm Outlook Narrative (AC)
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ACUS03 KWNS 300729
SWODY3
SPC AC 300729

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CDT Thu Mar 30 2017

Valid 011200Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS
SURROUNDING AREAS OF THE CENTRAL AND SOUTHERN PLAINS INTO MID/UPPER
TEXAS COASTAL AREAS...

...SUMMARY...
Scattered strong to severe storm development is possible Saturday
across parts of the central and southern Plains into mid/upper Texas
coastal areas.

...Synopsis...
Models indicate that a broadening/weakening mid-level circulation,
centered east/southeast of the Four Corners region by 12Z Saturday,
will elongate and weaken further during this period.  Considerable
variability exists among the models concerning this evolution, but,
in general, one emerging perturbation may pivot northeastward
through the central Plains Saturday/Saturday night, while one or two
others dig into the northern Mexican Plateau and Texas Big Bend
region.  These latter features may increasingly interact with a belt
of westerlies emanating from the subtropical eastern Pacific by 12Z
Sunday.

In lower-levels, it appears that surface cyclogenesis within lee
surface troughing across the southern Plains will remain weak or
negligible through this period.  However, modest southerly low-level
flow to the east of the lee trough may allow for increasingly
substantive moistening, within at least a narrow corridor across
parts of central/eastern Texas and Oklahoma.  This probably will
contribute to sufficient destabilization to support increasing
thunderstorm activity.

..Cntrl/srn Plains into Rio Grande Valley/Texas Gulf Coast..
While it remains possible that conditions could evolve in manner
that could support appreciable severe weather potential on Saturday,
this is far from certain at the present time.  Model variability
concerning the smaller scale features and their evolution adds to
the uncertainty.

Scattered thunderstorm development is possible to the east of the
surface trough across parts of Kansas southward through Oklahoma
during the day Saturday in response to forcing associated with the
lead impulse.  This may occur to the east of dryline expected to
become better defined across parts of western Oklahoma into west
central Texas by late afternoon, and perhaps prior to appreciable
boundary layer moistening and destabilization.  The progression of
this impulse may also result in stronger lower/mid tropospheric flow
becoming displaced to the east of the dryline, before low-level flow
possible begins to back and strengthen near the dryline in response
to approaching upstream perturbations.

Depending on the progressiveness of the consolidating impulses over
the Mexican Plateau/Texas Big Bend/Rio Grande Valley, it may not be
out of the question that a more substantive risk for severe
thunderstorm development could evolve across parts of the lower Rio
Grande Valley through the Texas Coastal plain Saturday night.
Better boundary layer moisture return, increasing vertical shear and
forcing for large-scale ascent could all contribute to
organizing/upscale growing convective development with severe
hail/wind potential prior to 12Z Sunday.

Regardless, areas of developing moderate to strong vertical shear
and weak to modest destabilization could support isolated to widely
scattered strong/severe storm potential Saturday through Saturday
night.

..Kerr.. 03/30/2017

$$



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