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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ACUS02 KWNS 080554
SWODY2
SPC AC 080553

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1253 AM CDT Mon Apr 08 2024

Valid 091200Z - 101200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS IN SOUTHEAST TX
TO WEST LA...

...SUMMARY...
Severe thunderstorms are expected from Tuesday into early morning
Wednesday across most of Texas towards the Lower Mississippi River
Valley. Several tornadoes, a couple of which should be strong,
significant large hail, and damaging winds are likely.

...Synopsis...
A shortwave trough centered near the AZ/NM/northwest Mexico border
area at 12Z Tuesday will progress steadily eastward into west TX
by early Wednesday. Two separate mid-level speed maxes, one curling
through the base of the trough and another farther east closer to
the northwest Gulf Coastal Plain will gradually translate eastward,
likely phasing by 12Z Wednesday. As this occurs, multiple surface
lows should consolidate into a primary cyclone in the southeast TX
vicinity early Wednesday.

...TX/LA...
Several rounds of deep convection are expected across a large
portion of TX towards the Ark-La-Tex and Lower MS Valley vicinity
during the period. A corridor of enhanced severe potential is
evident across a part of southeast TX into west LA, where the
environment should be most favorable for regenerative supercells and
organized clustering.

An MCS will likely be ongoing at 12Z Tuesday in the Ark-La-Tex to
Ark-La-Miss vicinity with scattered to widespread convection
trailing westward into west TX. An isolated supercell or two may be
ongoing in the south-central TX area as well. Primary convective
coverage during the day will be tied to the persistent
low-level warm theta-e advection regime, with regenerative periods
of convection expected across at least east TX to the Ark-La-Miss.
Surface heating of a richly moist Gulf air mass to the south of the
convective plume, coupled with steep mid-level lapse rates from 8-9
C/km should support a broad swath of moderate to large buoyancy by
afternoon. This will yield an uptick in severe storms in a portion
of southeast TX to west LA. Although convective mode should
predominately consist of clusters, embedded supercells are expected
within a favorable low-level hodograph and deep-layer shear,
supporting all severe hazards.

Farther west, isolated convective redevelopment should occur during
the early evening along the trailing outflow boundary intersection
with the dryline/surface trough in the central TX vicinity.
Low-level shear should be substantially weaker relative to the
Sabine Valley, but the favorable deep shear/thermodynamic
environment should yield a threat for significant severe hail. An
increase in storm coverage is expected Tuesday night across
south-central TX to southwest LA. Overall tornado potential should
be centered on the Sabine Valley, with potential for discrete
warm-sector supercells merging into the residual large-scale outflow
boundary. A couple strong tornadoes will be possible.

Finally, in west TX, early-day large hail potential should subside
for a time, before additional storms refire later into the afternoon
near the mid-level trough. While surface winds should largely be
northerly by this time, adequate buoyancy within the approaching
mid-level cold pocket will yield a renewed threat for large hail.
This should wane after dusk.

...Lower Great Lakes...
The drifting mid/upper low over the Upper Great Lakes/northern
Ontario will aid in scattered showers and lower-topped thunderstorms
across the Lower Great Lakes vicinity on Tuesday afternoon. A plume
of low-level moisture being advected northeast from the Lower MS
Valley, coupled with differential boundary-layer heating south of
the stratocu field attendant to the northwest Ontario surface
cyclone, should yield a plume of MLCAPE around 500 J/kg. Adequate
speed shear within the deep-layer southwesterly flow regime should
support a threat for isolated severe hail and locally strong gusts.

..Grams.. 04/08/2024

$$
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