Severe Storm Outlook Narrative (AC)
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ACUS01 KWNS 242010
SWODY1
SPC AC 242008

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0308 PM CDT Fri Mar 24 2017

Valid 242000Z - 251200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EAST
TEXAS AND THE ARK-LA-TEX REGION...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL STATES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK AREA ACROSS THE SOUTH-CENTRAL STATES...

...SUMMARY...
Scattered severe storms are expected across parts of the
south-central U.S. late afternoon into tonight. Damaging winds and a
few tornadoes appear most likely over parts of east Texas and the
Ark-LA-Tex region.

...Southeast TX/Western LA to southwest AR...
Previous forecast reasoning remains valid for the severe-weather
development and attendant risks across this region, though latest
guidance (HRRR and ESRL-HRRR) indicated UH tracks will be possible a
little farther south across southeast TX and into more of southwest
AR.  The 5% and 10% tornado probabilities have been adjusted
accordingly, and the Enhanced severe risk area has been expanded a
little south for this greater tornado threat.

...Parts of eastern OK/north-central TX...
Given trends in radar imagery and model data, the slight risk and
severe probabilities have been trimmed from part of eastern OK and
the eastern part of north-central TX.  Otherwise, the previous
forecast remains valid for the rest of far eastern OK into northeast
TX.

..Peters.. 03/24/2017

.PREV DISCUSSION... /ISSUED 1132 AM CDT Fri Mar 24 2017/

...East TX/Ark-LA-Tex region to lower MS River Valley...
The nearly closed cyclone centered over the south-central High
Plains late this morning will reach the Ozarks vicinity by early
Saturday morning. Ahead of this cyclone, low-level moisture will
gradually increase and spread northward through the afternoon ahead
of a north/south-oriented Pacific cold front/effective dryline.

Although considerable cloud cover precedes the cold front, current
thinking is that storms will initially intensify across parts of
east-central/northeast TX by mid/late afternoon as low-level
confluence increases and trough-related DPVA overspreads the region.
Effective shear magnitudes around 50 kt will support organized lines
and some embedded supercell structures with a mixed severe hail/wind
risk as storms mature. After a modest diurnal slackening,
south-southwesterly winds in the lowest 2-3 km AGL are expected to
increase in earnest by early/mid evening from far east Texas across
western/northern Louisiana and much of Arkansas. This will
nocturnally enlarge low-level hodographs while contributing to the
likelihood of embedded bows/circulations with related damaging
wind/tornado risks.

...Portions of KS/lower MO River Valley...
Low-topped convection is expected to develop this afternoon on the
immediate east/northeast periphery of the nearly vertically stacked
south-central Plains-centered cyclone. The appears most probable
near the surface occlusion and effective dry line across central and
eastern portions of KS. Some severe hail will be possible aside from
gusty winds. While the setup appears far from classic for
cold-core-related tornadoes given that late-stage-weakening trend of
the cyclone and southeastward-progressing front, a few funnels or
brief tornado cannot be entirely ruled out this afternoon across
east-central KS. Farther east, a somewhat separate corridor of
mostly linearly organized strong/severe thunderstorms are expected
near the cold front across parts of MO.

$$


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