FROPA convection on the Plains

Strong early September convection fired on a trailing cold front in the late evening and overnight hours in northern OK, southern KS, and southwest MO. The environment near and along the front was characterized by MUCAPE ~2500-4000 J/kg and effective shear ~20-35 kts. The IR-derived satellite growth rates, as captured by the NOAA/CIMSS ProbSevere model were very strong, during this period of GOES-East rapid-scan operation.

GOES-East IR brightness temperature, 5-minute NLDN lightning plot, and METAR station plots.

 The explosive growth rates, along with strong MRMS MESH and a favorable environment, led to very high probabilities of severe (80-100%) before severe weather was reported from many of these storms.

ProbSevere contours overlaid MRMS reflectivity and NWS warnings.

 The first storm to initiate in south-central KS (shown below) went from 10% (22:30Z) to 57% (22:34Z) probability of severe as the observed satellite growth went from moderate/weak to very strong, while the MESH remained constant at 0.25". Six minutes later, the probability of severe was 79% (MESH still < 0.5"). By 22:52Z, the probability of severe exceeded 90%, as the MESH was nearly 0.75". The probability maxed-out at 100% at 23:14Z, when the MESH was 1.47" and the first 1" report was also recorded at this time. This storm would go on to produce a large tornado near the town of Cedar Vale, in Chautauqua county, as well as baseball-sized hail in Winfield, KS.

The storms in the region produced numerous severe weather reports, including hail up to the size of baseballs, wind gusts up to 80 mph, and large tornadoes. The satellite growth rates from the model may increase forecaster confidence in issuing warnings and perhaps increase lead-times to initial severe hazards.

John Cintineo
UW-CIMSS