A Probabilistic Approach to Severe Weather Forecast Hazards for the El Paso Area

Severe weather hazards prediction for arid regions of the Intermountain West presents a forecast challenge. Minimal research has been performed in the WFO El Paso area on this topic. Synoptic and mesoscale weather features interacting with the Intermountain West’s complex topography  and rapid elevation changes show a need for different parameters for predicting severe weather events . Standard severe weather thresholds, considered helpful elsewhere, are not necessarily useful in mountain regions.

In order to understand better the nature of the unique weather environments in the area, upper air data were gathered and processed to create a sounding climatology from 1985 to 2015 for the El Paso area (KEPZ). Past occurrences of severe weather events were pulled from Storm Data and compared with soundings for those days. Soundings were grouped and categorized by specific hazards for hail, damaging winds, tornadoes or flash floods. A statistical analysis was performed to establish thresholds for each severe hazard type. From these data a hazard climatology was developed. This hazard climatology is used operationally at WFO El Paso through comparison with the latest 1200 UTC KEPZ sounding. The results of this comparison establishes probabilities of experiencing each of the different thunderstorm hazards for that day.

A version of this methodology is used at WFO San Juan, where it has helped predict the likely storm environment and hazard types.  This has been useful in preparing forecast discussions and providing long lead time decision support services to our partners in the media and emergency management. For WFO El Paso, the goal of this tool is to help forecasters to recognize patterns associated with severe weather.  In addition, this hazards climatology will show patterns or indicators that could lead to further areas of research to help improve severe weather forecasting in the desert southwest.