Shreveport, LA...Tyler, TX...Longview, TX...Bossier City, LA...Monroe, LA...
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Oklahoma City, OK...Tulsa, OK...Wichita, KS...Birmingham, AL...Baton Rouge, LA...
SPC AC 180559
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Sun Mar 18 2018
Valid 181200Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTH TX AND
THE RED RIVER VALLEY THROUGH THE CENTRAL GULF COAST STATES TO
SOUTHERN GA AND FAR NORTHERN FL...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK INTO OK AND KS...
Scattered severe storms are possible from North Texas and far
southern Oklahoma through the Gulf Coast and part of the Southeast
States. Isolated severe storms will be possible, mainly this
evening and tonight across central and southern Kansas into northern
A compact shortwave trough rounding the base of the western U.S.
longwave trough by the start of Day 1 will progress east today
reaching the southern High Plains by 00Z, with a closed cyclone
forming within this trough as it moves through OK and southern KS
tonight. As this trough deepens, an accompanying 500-mb westerly
jet will strengthen to 100+ kt across NM late this afternoon, and
then through the Red River Valley into AR this evening through early
Monday. Meanwhile, in the southern stream, a lead midlevel impulse
will track through the lower Mississippi Valley to the Southeast
States today, while a better defined upstream trough moves into the
southern Plains to the Ozark Plateau this afternoon and evening.
At the surface, a cold front, attendant to a midlevel trough moving
off the Mid-Atlantic Coast this morning, will advance south into
southern GA and central or southern AL by this afternoon. The
trailing portion of this front should remain generally stationary
from central MS to North TX, where a triple point should be located
by this afternoon across north-central TX (near or west of the DFW
Metroplex). Meanwhile, strong height falls spreading into the
central and southern High Plains, with the approach of the
progressive Southwest States trough, will result in a deepening low
across eastern CO this afternoon and equatorward-extending lee
trough. This low is expected to track into OK late tonight with a
warm front advancing north through eastern OK into northern portions
of the central Gulf Coast States.
...North and northeast TX/South and southeast OK to western MS...
Forcing for ascent attendant to a southern-stream trough tracking to
the east-northeast into the southern Plains by early-mid afternoon
and height falls with the approach of the Southwest States trough
are expected to prove sufficient for the development of a few
thunderstorms near a triple point in north-central TX between
19-21Z. Surface heating from south-central OK southward along the
dry line combined with dew points south of the stationary front in
the 60s and cooling 500-mb temperatures will result in MUCAPE up to
1500 J/kg in the warm sector. This combined with strengthening bulk
shear (exceeding 50 kt) will support supercells with very large hail
and damaging gusts. An increase in low-level hodograph curvature by
late afternoon to the evening suggests a tornado threat will be
possible as storms that form in North TX into far southern OK spread
east into the Arklatex region this evening. ESRL-HRRR suggests
storm mode could become linear as storms advance into western MS
later this evening.
...Lower Mississippi Valley/Central Gulf Coast and Southeast
Thunderstorm development will be possible across the lower
Mississippi Valley through southern parts of MS/AL into southern GA
as the environment destabilizes. Effective bulk shear will be
sufficient for organized storms, with clusters of storms possibly
focused along the track of weak midlevel impulse shifting east from
the lower Mississippi Valley this morning. Strong wind gusts should
be the main severe threat, given weak midlevel lapse rates tending
to temper the hail threat.
...KS/OK and eastern TX/OK Panhandles...
Mainly elevated storms will be possible as forcing for ascent with
the southern-stream trough moves through OK by late morning into the
afternoon, with isolated hail being the main threat. Thereafter,
strong forcing for ascent and rapid cooling in the midlevels
(between 400-600 mb) are expected to occur across parts of KS and
across the OK/TX Panhandles into OK this evening through tonight.
Given that these dynamics will not arrive in this region until after
peak heating, the potential for surface-based thunderstorm
development is low, with greater likelihood for elevated storms. In
addition, meager moisture return into KS will limit stronger
instability with north/northwest extent. Isolated hail will be the
main threat with the storms that form and move to the east and
northeast this evening into tonight.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z