SPC AC 211647

   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

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z