The GOES-R Overshooting Top (OT) Detection algorithm (applied to current GOES) was utilized during the very early morning hours of June 23 across the Texas panhandle and western Oklahoma. This algorithm, which automatically detects the location of OT’s using the GOES IR window channel, has proven to be especially valuable in monitoring the evolution of mature convection, especially overnight in the absence of the higher resolution visible imagery. As has been mentioned in previous posts, OT’s indicate the presence of strong updrafts within a convective system, and likely areas of hazardous weather. The algorithm provides forecasters with a tool to quickly spot, in the imagery, where OT’s are present as well as trends in the feature.
By 0400Z on the 23rd, an MCS was propagating across the Texas panhandle/western Oklahoma, producing heavy rainfall and severe winds across the region. An SPC forecaster on shift viewing the OT product utilized it to help monitor trends in the strongest updrafts and areas most likely to be experiencing hazardous weather. The forecaster mentions in a 0723Z SPC Watch Update Mesoscale Discussion (MD,Fig. 1): “TRENDS IN 7 KM AND 9 KM CAPPI AND GOES-R OVERSHOOTING TOP PRODUCT INDICATED THE MORE PERSISTENT UPDRAFTS SINCE AT LEAST 0530z HAVE BEEN FROM THE SRN TX PANHANDLE INTO WRN OK…WITH FORWARD MOVEMENT OF THIS ACTIVITY AT 35-40 KT TOWARD THE SSE.”
Figure 2 is an animation of GOES-East IR imagery with overshooting tops and SPC storm reports overlayed during the time of and in the vicinity of the MD. Notice the cluster of persistent Overshooting Tops within the large cloud shield across the Texas panhandle between 0415 and 0530Z. This is where the highest concentration of severe weather (and heavy rainfall) was reported. Between 0530 and 0730 UTC, the MCS continued to propagate to the SSE as the overshooting tops became more spread out along the leading edge of the system from the southern Texas panhandle into western Oklahoma, as was mentioned in the MD. A few wind reports and heavy rainfall were reported in the vicinity of the persistent OT’s. After 1000Z, the OT’s dropped off completely as the MCS began to weaken.
-Bill Line, SPC/HWT Satellite Liaison