A prominent ridge will begin building in after today, bringing a downward slide to our major severe weather chances for awhile — though risks will remain. Still, with weak flow aloft coming, tornado risks will likely be very low to just about zero for awhile. That said, today, we have one last tornado risk to contend with before that happens.

Scattered severe storms with large hail up to baseball size, damaging winds of 60-75 mph, and a couple of tornadoes are expected this afternoon into tonight from west into central Texas. More isolated severe storms are possible today from the Red River Valley into east Texas and southwest Texas.

Locations:

  • Primary Risk Area: Texas South Plains and Big Country
  • Secondary Risk Area: Surrounding the primary risk area.

Threats:

  • Large Hail: Up to baseball size.
  • Damaging Winds: 60-75 mph
  • Tornadoes: A couple of tornadoes are possible

Timing:

  • Storm Initiation: This afternoon
  • Peak Threat: Afternoon into early tonight

Discussion:

Southern Plains

  • Setup: Multiple small thunderstorm clusters are ongoing across southern KS/northwest OK, northwest TX, and the TX Panhandle. The warm sector across TX/southern OK has recovered, with boundary-layer dewpoints into the upper 60s in northwest TX and the upper 70s along the TX coast.
  • Storm Development: The clusters moving east-southeastward along the northern edge of the richer moisture/buoyancy will likely be the most influential today, with potential for severe outflow winds of 60-70 mph and isolated large hail of 1-1.75 inches in diameter from north into east TX. Convective outflow is expected to spread southwestward, focusing additional severe storm development this afternoon/evening across the TX South Plains and Big Country.
  • Severe Potential: Strong buoyancy (MLCAPE of 2500-3500 J/kg), steep midlevel lapse rates, and effective bulk shear of 35-40 kt will support supercells with initial storm development in the primary risk area. The southern-most/more discrete storms will have the more significant potential to produce huge hail near baseball size (2.75 inches) and a couple of tornadoes if storms can interact favorably with zones of enhanced low-level moisture/shear along the residual outflow boundary. Upscale growth into another MCS is probable tonight, with occasional damaging winds and large hail continuing well into the overnight hours into central/north TX.

KS/CO/NE

  • Setup: Prior convective overturning and lingering convection in KS cast doubt on any specifics regarding the severe threat north of the ongoing TX storm clusters.
  • Storm Development: Residual low-level moisture and surface heating in cloud breaks later today could result in sufficient destabilization for a few strong-severe storms with hail/wind. However, vertical shear will be relatively weak in most areas along and south of the slow-moving front from CO to NE, which, combined with the effects of prior convection, could limit the overall severe threat.
  • Severe Potential: Confidence in the forecast is low. But assuming storms, expect hail/wind as the primary threat.

Technical Discussion

Refcmp uh001h.us sc-34.

Initial storms should fire along the New Mexico/Texas border region on a dryline in the mid/late afternoon hours. Some of these will quickly acquire supercell characteristics, especially in the zone of enhanced shear near a residual outflow boundary, which will be draped somewhere in the Lubbock to Abilene area.

Nam4km 2024053012 011 34.38--100.8.

Without a boundary in place, low-level shear is only barely favorable for supercell development. The added vorticity along a boundary, mixed with the extreme instability, should allow supercell development to be nearly instantaneous for storms in the boundary zone.

850wh.us sc.

There is little rhyme or reason for how the 850mb winds are organized today, which means low-level shear will be particularly weak as we move into the evening hours. But, again, a boundary and SE storm motion will enhance what little shear there is to be a bit more substantial.

Hrrr 2024053013 011 32.48--99.0.

Still, by evening, some more substantial shear will set in downstream of the initial storms, with an environment highly favorable for giant hailstones and a tornado or two. An effective SRH of 202 will be favorable for any robust/dominant supercell with a clean inflow to produce a tornado, perhaps locally strong, if a storm interacts favorably with a boundary and enhances this already sufficient profile. We’ll have to wait and see if that’s the case. The tornado risk largely depends on storm mode and evolution, and it seems just as likely we’ll have a linear system vs. isolated supercells by evening.