Thunderstorm Wind in Tulare County, California

NWS officials toured damage around the town of Orosi in Tulare County. Extensive wind damage from thunderstorm outflow in the town was evident. Several homes exhibited minor roof damage. Fences and trees were damaged or downed. Property damages were estimated. NWS concluded that a gust front tornado, commonly called a gustnado, occurred in this location, based on damage pattern as well as patterns indicated in tall dry grass and tree trunks and tops, and eyewitness accounts. Gust front tornadoes can occur in the outflow of a severe thunderstorm and are not considered to be true tornadoes. Winds were estimated at 60 mph.

An upper-level ridge built into California beginning May 27th, bringing another warming trend to interior central California. Fresno warmed to 99 degrees on the 27th, and reached 102 the next day. A weak low off Baja California spun mid-level moisture into California from the south, and the combination of heat and moisture triggered strong thunderstorms over the Southern Sierra Nevada and the Tehachapi Mountains each afternoon and evening, beginning on May 27th and continuing through the end of the month. Hail up to 1.5 inch in diameter fell near the town of Orange Cove on the evening of the 28th, and as thunderstorms over the Sierra Nevada, and over San Luis Obispo County, collapsed, outflow winds pushed across the San Joaquin Valley, triggering thunderstorms over the eastern and central Valley. Two of the storms merged into a strong system that produced gusty winds that toppled numerous trees on the Valley floor, as well as 1-inch hail near Visalia. Strong winds also triggered a gust-front tornado (gustnado) that damaged a mobile home park in Orosi.

Convection was weaker on May 29th, as thunderstorms developed earlier and several of the storms were pushed north of the region by a more southeasterly flow aloft. However, this southeast flow also carried thunderstorms from northeastern Los Angeles and northwestern San Bernardino Counties into southeastern Kern County near Rosamond, Edwards AFB, and Boron. One thunderstorm collapsed as it passed west of Edwards AFB in the early afternoon, generating outflow winds that were measured at a peak of 62 knots (71 mph).