A negatively-tilted shortwave brought some low-level moisture return to the gulf states this week, and with the moisture, some scattered severe storms.
A couple tornadic storms affected portions of east Texas. The
NOAA/CIMSS ProbSevere model now incorporates the GOES-16 satellite growth rates, and a storm affecting Cherokee Co., TX, had a strong normalized growth well before it produced severe weather.
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| Figure 1: AWIPS2 screen captures of MRMS MergedReflectivity, ProbSevere contours, and NWS warnings for a storm near Rusk, Texas. |
The ProbWind values vacillated largely between 50% and 75% for this storm, before producing a tornado at 00:56 UTC and multiple wind damage reports in the town or Rusk, TX. The strong GOES-16 vertical growth rate, large ENI flash rate (~30-70 fl/min), and stout kinematic fields (eff. bulk shear ~ 45-50 kts; meanwind 700-900mb ~ 35 kts) combined to produce these moderate-strong ProbWind values. The MRMS MESH remained rather low (~ 0.2 - 0.6 in), signaling that this was not a severe hail situation. ProbTor had a maximum value of 12% before the first tornado report.
This storm featured jumps in ProbWind value (one produced by a large increase in flash rate, indicative of a lightning jump), and being an outlier storm amongst its neighbors, in terms of probability value. Both features in ProbSevere objects have been identified by forecasters as indicating possible severe weather.
A second storm formed further south and later in the night, which also produced a damaging tornado, touching down northeast of Beaumont, TX, and later northwest of Lake Charles, LA, blowing off the roof to a restaurant.
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| Figure 2: AWIPS2 screen captures of MRMS MergedReflectivity, ProbSevere contours, and NWS warnings for storm heading into southwest Louisiana. |
The kinematics for this storm were very favorable, with effective bulk shear of 50 kts, meanwind 700-900mb of 45 kts, and 0-1 km storm-relative helicity near 300 J/kg. The first tornado touched down at 07:41 UTC, when ProbTor was about 30%. ProbTor then jumped from 30% to 50% at 08:00 UTC, the time of the second tornado report. This jump in ProbTor value was coincident with an increase in total lightning (a lightning jump) as well as an increase in low-level rotation.
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| Figure 3: Time series of ProbTor and predictor values for this storm affecting southeast TX and southwest LA. |
A tornado warning was issued at 08:10 UTC, when ProbTor had just increased to 90%. The third tornado reported, at 08:20 UTC, was rated EF1 and destroyed the roof of a restaurant in DeQuincy, Louisiana.
