ACUS02 KWNS 130601
SWODY2
SPC AC 130559
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Wed Mar 13 2024
Valid 141200Z - 151200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
OK INTO WESTERN AR AND FAR SOUTHWEST MO...
...SUMMARY...
Strong to severe thunderstorms are possible across a large area from
the Middle Mississippi Valley into eastern Oklahoma, East Texas, and
the Lower Mississippi Valley on Thursday. Greatest threat is
currently expected to be from southeast Oklahoma into western
Arkansas.
...Synopsis...
A surface low is forecast to be over the NE/IA/MO border
intersection vicinity early Thursday morning. A cold front will
extend from this low southwestward through southeast KS and central
OK into the TX Hill Country. A warm front will extend from this low
east-northeastward through central IL. A broad warm sector will
exist ahead of the cold front Thursday morning, characterized by
dewpoints ranging from the mid/upper 60s over east TX to the mid 50s
near the IA/MO border. This reservoir of low-level moisture will
exist beneath steep mid-level lapse rates, resulting in moderate to
strong buoyancy as heating destabilizes the air mass. As such,
thunderstorms are anticipated across much of the warm sector as the
cold front gradually shifts eastward throughout the day. Some strong
to severe storms are possible, particularly in the corridor from
northern MO into the Arklatex.
...Mid MS Valley Thursday morning into late afternoon/early
evening...
Showers and thunderstorms will likely be ongoing near the surface
low and warm front early Thursday morning. General expectation is
for most of this activity to be north of the warm front, with an
attendant threat for isolated hail. However, there is some potential
for the southern edge of these storms (and associated outflow) to
move within the far northern corridor of the warm sector, resulting
in some threat for damaging gusts as well as hail. This activity is
expected to continue eastward, reaching the Middle OH Valley by the
afternoon.
The presence of these early morning storms could act to shift the
position of entire the frontal zone southward, with an attendant
shift of the afternoon severe threat as well. Additionally, if
strong outflow is realized, the resulting boundary could act as a
focus for afternoon development across MO. Evolution of these
mesoscale details varies within the guidance, but the more favorable
area for afternoon development does appear to be over central MO,
which is farther south than forecast yesterday when the area just
south of the warm front looked more plausible. Given steep mid-level
lapse rates and strong deep-layer vertical shear, large to very
large hail is still anticipated with the initial more cellular late
afternoon storms. Strong downdrafts are possible as well, with
potential for upscale growth into one or more bowing clusters.
Veered low-level flow is forecast to limit the tornado potential,
although interaction with any boundaries could lead to mesoscale
corridors of slightly greater tornado threat.
...Middle OH Valley during the afternoon and evening...
As the activity initially over the Mid MS Valley continues eastward,
there is some potential it transitions from elevated to surface
based (or at least near-surface based) as it interacts with the warm
front progressing northward across the region. Buoyancy will be
modest, but moderate southerly low-level flow beneath strong
westerlies will result in vertically veering low-level hodographs
that could support updraft organization and even a few tornadoes.
Uncertainties regarding the position of the front as well as how the
convection evolves out of the Mid MS Valley limit forecast
confidence with this outlook, but future guidance will be evaluated
closely, and upgrades may be considered in later outlooks.
...Far Northeast TX and eastern OK into AR during the afternoon and
evening...
Large-scale forcing for ascent will be nebulous over the region,
with some guidance even showing height rises during the afternoon.
Even so, weak surface troughing is expected to interact with an
increasingly unstable airmass across the region during the
afternoon, resulting scattered thunderstorms from far northeast TX
into eastern OK and western AR between 18Z and 21Z. Given robust
buoyancy and moderate vertical shear, initial development will
likely be supercellular and capable of all severe hazards, including
very large hail. Low-level southerly flow (perhaps even
southeasterly) is also anticipated, resulting in low-level
hodographs that support tornadogenesis, particularly from far
southeast OK into western AR. Even with favorable hodographs, storm interactions
could prevent the discreteness needed for updraft
organization.
...Mid MS Valley into the Mid-South during evening and overnight...
After the initial development described above, some upscale growth
into one or more clusters appears plausible, with an attendant
threat for damaging gusts as these clusters move eastward. Buoyancy
will gradually decrease with eastward extent, leading to the
expectation that whatever line segments do develop will lose
intensity as they continue eastward overnight.
..Mosier.. 03/13/2024
$$
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