All day we were watching weak convection along a cold front in the Central Plains and ProbSevere as expected with these weak storms was no higher than 5 percent. Later in the afternoon, a few isolated cells in the Texas Panhandle rapidly developed. One storm, the Clarendon storm, became severe within an hour of initiation. We utilized ProbSevere as guidance in determining which storms to focus on for potentially severe hail. ProbSevere made it easy to see the evolution and intensification of the individual cells. Eight minutes before the Clarendon warning, ProbSevere was 43%, two minutes later it was up to 72%, another 4 minutes later it was up to 96%. At warning issuance another 2 minutes later it was 98%. ProbSevere performed well with regards to hail size. During this 8 minutes the MESH increased from .71 to 1.8 inches. After the warning was issued, it continued to increase to 2.4 inches. Local storm reports of 1 to 2.5 inch diameter hail were received.
Nearby cells that were developing around this time had a ProbSevere of 80-98%, however none of these cells had a warning except for the Clarendon storm during the initial time period studied. A half hour later the warning over the Clarendon storm was expanded to include most of the nearby cells that ProbSevere had high probabilities for earlier. There were no storm reports issued as of 15 minutes into the warning for the other cells but regardless there was a warning consistent with the ProbSevere guidance.
Sarah Marquardt and Sean Miller
NWS Milwaukee/Sullivan
