ACUS01 KWNS 111248
SWODY1
SPC AC 111247

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0647 AM CST Tue Feb 11 2025

Valid 111300Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
TEXAS AND THE LOWER MISSISSIPPI VALLEY INTO SOUTHERN MISSISSIPPI AND
CENTRAL ALABAMA....

...SUMMARY...
Isolated to scattered thunderstorms are possible from the southern
Plains into the lower Mississippi Valley. Some strong to severe
thunderstorms are possible from southeast Texas and the Lower
Mississippi Valley into southern Mississippi and central Alabama.

...Synopsis...
A pair of shortwave troughs are expected to progress through the
southern Plains today as the cyclonic flow aloft across the western
CONUS deepens. The first of these shortwaves is currently moving
through the southern High Plains while the second remains off the
coast of the northern Baja Peninsula. Both of those shortwaves are
expected to progress quickly eastward, with the lead wave reaching
the Mid-Atlantic by early Wednesday and the second shortwave
reaching central TX.

...Lower MS Valley into southern/central MS and AL...
As mentioned in the synopsis, the lead shortwave trough is currently
moving through the southern High Plains, with preceding warm-air
advection contributing to an expansive area of precipitation from
the TX Hill Country into the Mid-South. General expectation is that
this area of precipitation will gradually shift northeastward
throughout the day, remaining just ahead of the eastward-progressing
shortwave. Low-level moisture return ahead of the first wave will be
modest, particularly across TX where the modified Gulf moisture will
likely remain confined to the coastal plain. Farther east, greater
inland moisture advection is anticipated, with mid 60s dewpoints
advection through much of the Lower MS Valley by the early
afternoon. Lower 60s dewpoints are likely in the central portions of
MS and AL by the late afternoon/early evening.

Even with this low-level moisture advection, mid-level temperatures
will remain warm, keeping the overall buoyancy modest (i.e. MUCAPE
less than 1000 J/kg) across the region. In contrast to the modest
buoyancy, vertical shear will be quite strong, with effective bulk
shear over 50 kt from the Lower MS Valley into AL and MS during the
afternoon and evening. This strong vertical shear may be able to
compensate for the lower buoyancy, and there could be a window for a
few strong to severe storms this afternoon/evening along and ahead
of the cold front from southern MS into southern and central AL.
Primary risk would be damaging wind gusts, but enough low-level
shear exists for a low-probability tornado threat as well.

...Southern Plains late tonight...
Strong large-scale forcing for ascent will spread across the
southern High Plains and into west TX late tonight ahead of the
second shortwave trough mentioned in the synopsis. Notable
moistening between 850 and 700 mb combined with mid-level cooling
will help support modest elevated buoyancy. Thunderstorms are
expected to develop across West TX tonight before then spreading
eastward/northeastward into more of OK and north/central TX. Much of
this activity will be displaced well north/northwest of front and
greater low-level moisture. Some hail is possible, but updraft depth
and duration will be limited by weak buoyancy, and the current
expectation is for any hail to remain very isolated.

As these storms move east/southeast with time, some interaction
could occur with a warm front gradually moving northward into more
of southeast TX early Wednesday morning. Increased buoyancy as well
as enhanced mesoscale ascent in the vicinity of the front is
expected to result in greater thunderstorm depth and duration.
Vertical shear will remain strong as well, with all of these factors
supporting a greater severe potential across southeast TX and
adjacent far southwestern LA early Wednesday morning. Damaging gusts
and/or a brief tornado are the primary threats.

..Mosier/Broyles.. 02/11/2025

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