SPC AC 210537

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1237 AM CDT Mon Mar 21 2022

   Valid 211200Z - 221200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL
   AND EASTERN TEXAS INTO EXTREME WESTERN LOUISIANA...

   ...SUMMARY...
   Severe thunderstorms capable of producing very large hail, damaging
   wind gusts, and several tornadoes are likely across portions of
   central and eastern Texas, starting this afternoon and lasting
   through much of the night. A couple of strong tornadoes are
   possible.

   ...Synopsis...
   A neutral-tilted trough will gradually traverse the southern Plains
   today as a surface cyclone gradually intensifies across northwestern
   Texas and propagates east-northeast. An embedded 500 mb impulse will
   pivot around the upper trough during the afternoon/early evening
   hours across Texas, encouraging the eastward shunting of a dryline
   across the Texas Hill Country while a warm front gradually drifts
   northward towards the Red River through the afternoon. Given
   prolonged deep-layer ascent from the approaching upper trough,
   coupled with a continuous feed of moist, buoyant air from the south,
   multiple rounds of strong to severe storms are expected across
   central/eastern Texas and surrounding areas this afternoon to 12Z
   Tuesday. All facets of severe will be possible.

   ...Central and eastern Texas into far southern Oklahoma today...
   The mid-level impulse embedded within the upper trough will
   overspread central and eastern TX by noon, accompanied by an 80+ kt
   500 mb speed max, which will in turn encourage the development of a
   60 kt 850 mb jet across central and eastern TX this afternoon.
   Deep-moisture/warm-air advection associated with the low-level jet
   will support widespread showers and elevated thunderstorms, starting
   in the morning. These preceding showers and storms complicate the
   forecast somewhat as they may impede the northward speed of surface
   airmass recovery. Nonetheless, latest guidance consensus shows 64 F
   dewpoints and surface-based buoyancy in far northeast TX by 00Z.
   Some marginally severe hail may accompany the initial WAA-driven
   elevated storms in northern TX/far southern OK. Later in the
   afternoon, semi-discrete supercells and small bowing-segments are
   expected to develop ahead of the dryline, given the presence of
   1000-2000 J/kg MLCAPE and 50+ kts of effective bulk shear. 8 C/km
   mid-level lapse rates closer to the dryline, along with
   unidirectional deep-layer shear, suggests that large hail will be
   the initial main threat across central into northern Texas, with
   some significant severe hail possible. As storms advance eastward
   into the moister environment and approach the low-level jet axis,
   storms may acquire stronger low-level rotation and produce
   tornadoes. A strong tornado may accompany any sustained, discrete
   supercell. Meanwhile, the linear segments may produce damaging gusts
   in addition to some severe hail.

   ...Eastern Texas into the Arklatex later tonight...
   As the main upper trough continues to advance towards the lower
   Mississippi Valley, earlier day storms may coalesce into more linear
   segments capable of several damaging gusts and at least a couple of
   tornadoes given the strong low-level shear. Several CAM guidance
   members depict the initiation of a second line of storms across
   eastern TX, which will advance towards Louisiana in the 09-12Z
   period. Given adequate buoyancy and long, curved hodographs,
   stronger segments/cells within the broader line may acquire strong
   rotation, capable of producing damaging gusts and tornadoes. A
   strong tornado is also possible with the more intense QLCS
   circulations given the magnitude of strong low-level shear.

   ...Portions of northwest Texas into southwest Oklahoma this
   afternoon...
   Modest low-level moisture will wrap around the eastern/northern
   portion of the surface low across northwest TX this afternoon,
   overspread by -20C 500 mb temperatures and steep mid-level lapse
   rates. Semi-discrete supercells will develop near the triple point
   along the northwest TX/southwest OK border by early afternoon. The
   cold temperatures aloft suggest that severe hail will be the main
   threat, with an instance of 2+ inch hail possible, though a couple
   damaging gusts and perhaps a tornado also cannot be ruled out.

   ..Squitieri/Broyles.. 03/21/2022

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