STORM2K

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1147 AM CDT Mon Mar 21 2022

Valid 211630Z - 221200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL/EAST TEXAS...

...SUMMARY...
Several tornadoes, including the potential for a few strong
tornadoes, along with very large hail and damaging winds are
expected this afternoon through tonight, especially across parts of
central/east Texas into western Louisiana.

...Northwest to south-central/east TX into southern OK...
Have introduced a Moderate Risk (Category 4 of 5) for portions of
central/east-central Texas centered on late this afternoon and
evening, including parts of the Interstates 35/45 corridors.
Expectations are for an initially semi-discrete supercellular mode
with very large hail and some tornado potential, transitioning by
evening to potential for large hail/damaging winds and tornadoes as
storms spread east-northeastward with a more complex convective mode
gradually evolving.

At midday, a closed upper trough continues to pivot eastward,
centered over southern New Mexico and nearby far northern Mexico,
with the exit region of a strong mid/upper-level jet (90+ kt at 500
mb) beginning to overspread central/east Texas. Cloud cover remains
rather persistent at midday within the warm sector, but this
sheltering/inhibited mixing is a contributing factor to the quick
north/northwestward advection of a moist air mass (70F surface
dewpoints) that is already becoming increasing well-established
across south-central/southeast Texas.

As robust mid-level DCVA occurs with a shortwave impulse ejecting
out of the basal portion of an amplified trough, surface-based
thunderstorm development is initially anticipated early to
mid-afternoon near the triple-point cyclone and arcing south along
the dryline during the late afternoon across portions of central to
south-central Texas. Cooling 500-mb temperatures and steep mid-level
lapse rates should foster potential for a few semi-discrete
supercells along this upper portion of the Red River Valley. Severe
hail and brief tornadoes will probably be the main hazards as
convection likely spreads into a less favorable environment with
northern extent in Oklahoma.

Convection farther southeast and south from north-central to
south-central TX will have a progressively larger warm/moist sector
ahead of the dryline. With MLCAPE likely to reach 1500-2000 J/kg in
conjunction with an approaching 80-kt 500-mb speed max, several
supercells should develop with a primary initial threat of very
large hail. The bulk of guidance suggests the low-level jet will
shift east-northeast during the evening which suggests that
low-level hodograph curvature and attendant SRH, while adequate for
tornadoes, may not be particularly large for the supercells
initiating along the dryline. Nevertheless, potential remains
apparently for a couple long-tracked supercells emanating from near
the I-35 corridor in central/south-central Texas east-northeastward
into parts of east Texas.

...Ark-La-Tex to southeast Texas...
With time this evening, one or more linear clusters with embedded
supercells and bowing structures should evolve from a combination of
initial dryline storms and regenerative convection within the warm
conveyor. A rather messy mode of severe hazards is expected to
accompany this evolution with an elongated slow-moving QLCS
anticipated overnight, as the primary shortwave impulse shifts
towards the Lower Missouri Valley and a secondary lobe hangs back
near the Texas/Mexico border. Amid an expansive swath of 50-60 kt
low-level flow and rich western Gulf boundary-layer moisture, all
severe hazards will remain possible through the overnight, although
probably on a more isolated basis in terms of coverage.

..Guyer/Kerr.. 03/21/2022