Severe Storm Outlook Narrative (AC)
Issued by NWS

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511
ACUS01 KWNS 290100
SWODY1
SPC AC 290058

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0758 PM CDT Sun May 28 2017

Valid 290100Z - 291200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM DEEP SOUTH
TEXAS TO THE LOWER MISSISSIPPI VALLEY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE COASTAL
CAROLINAS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE RIO
GRANDE VALLEY TO THE CENTRAL GULF COAST...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
EASTERN/CENTRAL CAROLINAS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
INDIANA AND OHIO...

...SUMMARY...
Severe thunderstorms capable of large hail and damaging winds will
remain possible this evening into tonight across portions of
southern/central Texas and Louisiana. Elsewhere, a few severe
storms, primarily capable of damaging winds, will move east across
the coastal Carolinas. A few lingering strong storms may produce
gusty winds over portions of Indiana and Ohio this evening.

...Deep South Texas to Louisiana...
A corridor of strong to severe thunderstorms persists this evening
from the Rio Grande Valley northeastward to northern Louisiana.
Along the northeastern edge of this corridor, a downwind-propagating
convective system has organized, and the air mass ahead of it is
characterized by moderate mixed-layer buoyancy and adequate
deep-layer shear. Therefore, this line should continue accelerating
southeast through the evening, with an attendant threat of damaging
winds, a couple instances of large hail, and perhaps a tornado.

Farther southwest, while mid-level flow (and resultant effective
shear) lessen, strong buoyancy (e.g., mixed-layer CAPE around 3000
J/kg on the CRP 00Z sounding) is fostering renewed convective
development along outflow boundaries. This development is resulting
in a general south/southeast propagation. Considering the ample
instability ahead of these storms, and modest (yet adequate)
deep-layer shear, clusters of strong/severe storms will likely
continue into the overnight as they push south/southeast. Thus, the
15-percent wind/hail probabilities are expanded to include more of
south Texas.

...Coastal Carolinas...
Within a moderately unstable environment, convection has organized
upscale into several small bowing segments accelerating towards the
coast. The downstream air mass remains favorable for damaging winds,
with the 00Z CHS sounding sampling plentiful DCAPE (around 1300
J/kg) and 40-50 kt westerlies between 700 and 500mb. Therefore, the
slight risk is adjusted southward to capture the ongoing severe
potential here.

...Ohio and Indiana...
Several small clusters of strong to marginally severe convection are
advancing eastward this evening, aided by residual surface-based
buoyancy and modest low/mid-level westerlies. With the loss of
diurnal heating, low-level instability will wane and overall
convective intensity will further diminish. However, an isolated
strong wind gust and/or marginally severe hail report may remain
possible for the next hour or two.

..Picca.. 05/29/2017

$$



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