Understanding a Threat: An Operational and Decision Support Perspective of the High Plains Tornado Outbreak of 12 June 2017 (238)

Chris Hammer, NWS, Cheyenne, WY

 

Abstract:

 

Understanding a Threat: An Operational and Decision Support Perspective of the High Plains Tornado Outbreak of 12 June 2017

Christopher L. Hammer

Meteorologist

National Weather Service, Cheyenne, Wyoming

A rare and historic tornado outbreak occurred across southeast Wyoming and the western Nebraska Panhandle on 12 June 2017. Severe thunderstorms resulted in at least 15 distinct tornadoes in the National Weather Service (NWS) Cheyenne (CYS) County Warning Area (CWA), including 4 strong (EF2) tornadoes. No fatalities or significant/life-threatening injuries were reported. Historically, significant tornadoes have occurred in this region. On 27 June 1955, an F4 tornado occurred in the city of Scottsbluff, Nebraska, and became the strongest tornado on record in the CYS CWA. An F3 tornado struck the city of Cheyenne, Wyoming, on 16 July 1979, resulting in 40 injuries and 1 fatality. These events are extremely rare as only 18 tornadoes have been rated as F2/EF2+ between 1980-2016 in the CYS CWA (NCDC). Until 2017, the last time multiple tornadoes of this magnitude occurred on the same day was 27 May 1985 in western Nebraska (NCDC). The 12 June 2017 outbreak was the most significant to affect southeast Wyoming and the western Nebraska Panhandle in the last 30 years.