A severe weather threats checklist to determine the Pre-storm environment

Determining the pre-storm environment is a critical step in the forecast process for determining severe weather potential. To aid in the assessment, a comprehensive severe weather threats checklist and value interpretation guide was developed, incorporating 16 of the most useful severe weather parameters for severe weather analysis. These parameters can be obtained from soundings available in AWIPS or the SHARP program (Hart and Korotky 1991) using local upper air sounding locations.

This paper documents three case studies in which completion and use of this checklist and value interpretation guide would have alerted forecasters to the immediate short term severe weather threats. The three cases documented include the Derecho high wind events of 20 April 1996 and 5 May 1999 in middle Tennessee and the tornado outbreak of 22-23 February 1998 in east central Florida. Examples of the severe weather checklist from these events are provided, indicating that such a compilation of sounding-derived indices and parameters can aid in improving short term severe weather forecast operations.

Application of the 16 sounding and hodograph parameters provided in this checklist and value interpretation guide gives forecasters a systematic method for the identification of potential storm-producing environments. Daily use of the checklist and value interpretation guide has aided in increasing forecaster recognition of the types of short term severe weather threats at NWSFOs in Nashville, TN and Melbourne, FL. The compilation of severe weather parameters has also helped forecasters improve the communication of the short term severe weather threats to the public, especially with the use of the Hazardous Weather Outlook (Special Weather Statement) and the Short Term Forecast (Nowcast) product. The correct analysis of the 16 sounding parameters provided in this checklist and value interpretation guide is another example of how the main short term severe weather threats can be assessed and communicated to the public. It must be noted that this severe weather checklist has operational utility especially for high shear environments when the greatest potential for life threatening severe weather exists.