Chasing in Western Texas

I’ll be chasing storms this weekend on both Saturday and Sunday across western Texas and the panhandle region.

A slow-moving upper level low will rotate east over the next few days. Ahead of the low, a moist, unstable air-mass will be in place. With the approaching low, increasing wind shear will set the stage for isolated to scattered thunderstorms. Some of the storms can produce large hail. There is also a damaging wind threat and a few tornadoes cannot be ruled out given the amount of low-level shear that is forecast.

Saturday may be slightly more active than Sunday, but both days should feature at least some severe thunderstorm activity.

Technical discussion:
The 4km NAM has consistently been firing a line of discrete thunderstorms across the Texas panhandle by mid-afternoon on Saturday. The model also shows CAPE values of 2000-3000 J/kg over much of the area with bulk shear in the range of 30 to 40 knots, with stronger shear around 50 knots in southeastern New Mexico. The HRRR and to some extent the RAP have a somewhat more ominious looking setup with localized CAPE values of over 3000 J/kg and bulk shear in the range of 50-60 knots from southeastern New Mexico into the Midland, Texas region. The HRRR fires discrete cells a bit further south than the NAM. A compromise between the two is probably a safe forecast. The wildcard right now is how quickly the atmosphere can destabilize after convection this morning. If clouds and showers linger across the panhandle, the strongest storms should stay further south. However, if conditions clear out up there, this threat could be a bit more widespread than originally thought.

While the trend this season (overall) has been for lackluster outcomes, the severe setups over the past few days have over-performed. The bullish looking HRRR guidance cannot be ignored, even if it is still a bit overdone.