21:15z: AzShear first caught my attention for an area to watch. Object marker quickly appeared and velocity indicated a very weak area of rotation. Next few scans showed the TORP probability increasing. This resulted in issuance of a tornado warning with ~4 minutes of lead time.

Top image: Weak velocity signature.

Middle image: First indication of AzShear picking up on an area and first object marker highlight.

Bottom image: TORP marker in AWIPS when decision to warn was made.