EF0 tornado in Polk County, Nebraska

A brief EF0 rated tornado skirted its way across northern Polk County in the early morning hours of May 21st. The tornado damaged trees, downed power lines and poles, and overturned several irrigation pivots. The peak wind was estimated to be 80 MPH.

A couple rounds of thunderstorms brings severe hail and wind to portions of south central Nebraska during the evening of May 20th and into the early morning hours of May 21st. The first round of thunderstorms developed between 6-7PM CDT along a retreating warm front that stretched W-E along roughly the I-80 corridor between Grand Island and York. This activity consisted of several semi-discrete supercells with primarily a severe hail threat of 1 to 2 inches in diameter. The greatest concentration of severe hail occurred in Hall County from Wood River to Grand Island. The severe threat with this initial round waned with loss of daytime heating between 8-9PM CDT.

A second round of severe weather, consisting of scattered to widespread convection along the existing W to E warm front, as well as an advancing N-S outflow from the west affected the area after midnight. Severe weather reports were generally limited to low-end severe wind (i.e. measured wind gusts 55-60 MPH), and somewhat hit and miss. The exception to this was along the Hwy 81 corridor in Fillmore and Polk Counties were wind gusts of 65-75 MPH were measured on a couple of mesonet stations. Also, a small (only 75 yds wide), weak tornado (EF-0) was surveyed in extreme NE Polk County where tree, power pole, and pivot damage was noted. The severe threat with this second round shifted east of the GID CWA by around 5AM CDT.