Moderate instability behind a warm front and cool northwest flow aloft yielded multiple strong and severe thunderstorms late this afternoon and evening. The first storm was a small supercell that moved slowly south across far northwest Castro County toward Easter; however, the only severe weather with this storm was observed farther north in Deaf Smith County (NWS Amarillo's County Warning Area). By early evening, a storm farther west collapsed over Friona accompanied by destructive downburst winds that damaged many trees, fences and caused minor damage to some buildings. A mesonet station northeast of Friona measured a wind gust of 88 mph. A third storm then erupted southwest of Dimmitt and moved very little over the course of 45 minutes resulting in torrential rains possibly in excess of four inches. These rains turned area fields into lakes and caused flooding of low-lying sections of FM 1055 near Flagg. This storm also produced intense downburst winds in Flagg that severely damaged a large grain bin, toppled two power poles and damaged area trees. Wind-driven hail up to 1.25 inches in diameter also caused significant crop damage in the Flagg area. Frequent lightning from separate storms farther south near Pep caused at least three wildfires; one of which grew to at least 100 acres in size and forced the evacuation of three homes. Fortunately, no one was injured and no homes were damaged. Storms then grew into a large complex which moved east-southeast across the South Plains and into the Rolling Plains. Although a few marginally severe wind gusts accompanied this complex, the storms brought much-needed soaking rains to the region with additional showers continuing through the night.

Wildfire in HOCKLEY, TEXAS
From 20-AUG-12 18:30:00 to 20-AUG-12 19:30:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A slow-moving thunderstorm near the community of Pep produced a tremendous amount of cloud-to-ground lightning resulting in at least three wildfires. One of these was fanned by outflow winds and grew to around 100 acres forcing the evacuation of three nearby homes. Fortunately, no persons were injured and no structures received damage from the fire.

Thunderstorm Wind in PARMER, TEXAS
From 20-AUG-12 17:10:00 to 20-AUG-12 17:12:00 (CST-6)
Location: FRIONA BENGER ARPK
Magnitude: 76.00 MG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Mesonet

A collapsing thunderstorm produced destructive downburst winds measured up to 88 mph by a Texas Tech University West Texas mesonet station northeast of Friona. Two quarter-mile long irrigation pivots located just east of the mesonet were flipped over. In Friona, similar winds caused widespread light to moderate structural damage mostly to fences, roofs and trees. A hangar door at the airport also sustained damage.

Flood in CASTRO, TEXAS
From 20-AUG-12 18:00:00 to 20-AUG-12 21:00:00 (CST-6)
Location: SUMMERFIELD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Torrential rains in excess of four inches fell over the course of one hour in and around the community of Flagg causing extensive flooding of fields and roads. Swift-flowing water was reported to be nearly three feet deep about 3/4 of a mile north of Flagg over FM 1055. An NWS storm survey the following morning noted water was still about 1.5 feet deep over the road. Combined with wind-driven hail, the floodwaters seriously damaged or destroyed many area crops.

Thunderstorm Wind in CASTRO, TEXAS
From 20-AUG-12 18:29:00 to 20-AUG-12 18:29:00 (CST-6)
Location: DIMMITT
Magnitude: 78.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An NWS storm survey in the community of Flagg confirmed significant downburst winds of around 90 mph from the east and northeast. These winds heavily damaged a large empty grain bin, shifted a nearby building that was bolted to concrete a few inches off its foundation, twisted pieces of metal on a grain elevator, knocked down two power poles, and caused various degrees of damage to trees.

Hail in CASTRO, TEXAS
From 20-AUG-12 18:30:00 to 20-AUG-12 18:30:00 (CST-6)
Location: DIMMITT
Magnitude: 1.25 
Crop damage: 100.00K
Reported by: Public

Hail slightly larger than quarters pummeled the Flagg community for nearly 30 minutes. Combined with ferocious downburst winds, hundreds of acres of mature corn and grain crops were destroyed or severely damaged. Torrential rains piled the hail into drifts nearly 12 inches deep in places. With record high corn prices, total crop losses would likely top $100,000.

Thunderstorm Wind in HALL, TEXAS
From 20-AUG-12 20:20:00 to 20-AUG-12 20:20:00 (CST-6)
Location: TURKEY
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Measured by a Texas Tech University West Texas mesonet.

Thunderstorm Wind in LUBBOCK, TEXAS
From 20-AUG-12 20:26:00 to 20-AUG-12 20:26:00 (CST-6)
Location: (LBB)LUBBOCK INTL AR
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The Lubbock ASOS measured a wind gust to 58 mph. No damage was reported.