Widespread supercell thunderstorms developed across the South Plains on the afternoon and evening of the 23rd producing very large hail, a tornado, and flash flooding.
From the night of the 22nd through the morning of the 23rd, a dryline surged westward allowing abundant low level moisture to return to the region. This dryline mixed to the east during the afternoon stalling around US Highway 385. A capping inversion initially kept convective initiation from occurring until late in the afternoon under a very unstable atmosphere with CAPE values in excess of 4000 J/kg. Initially, the most intense thunderstorm developed and became anchored over southwestern Garza County. This supercell exhibited strong rotation at low and mid levels of the storm. Several storm chasers observed a tornado over open land that lasted for about 11 minutes. Because of the very slow storm motion of this thunderstorm, the tornado was nearly stationary for its entire lifetime. A lack of roads in the path of the tornado prevented a storm survey from being completed, thus this tornado could not be rated.
Heavy rain fell over an extended period of time in Garza County due to the storm's nearly stationary movement. As a result, a portion of Farm to Market road 669 south of Post was washed out.
The thunderstorms that developed in the southeastern South Plains generated a strong outflow boundary which then moved through the central South Plains. This outflow boundary caused scattered thunderstorms to grow over Lubbock County in which many of these became severe over multiple parts of the city of Lubbock. Hail up to two inches was reported in the city of Lubbock along with wind gusts up to 62 mph. This outflow boundary continued to move northward creating additional severe thunderstorms over the extreme south-central Texas Panhandle. One of these storms produced hail up to three inches in diameter in the city of Silverton (Briscoe County) leading to widespread damage to vehicles.
Trailing stratiform precipitation from decaying thunderstorms generated a couple of non-thunderstorm severe wind gusts. One of these occurred at Caprock Canyons State Park where a Texas Tech University West Texas mesonet site measured a wind gust to 58 mph. The other was at the Automated Surface Observing System at Childress Municipal Airport measuring a gust to 58 mph.

Hail in LYNN, TEXAS
From 23-MAY-20 15:41:00 to 23-MAY-20 15:41:00 (CST-6)
Location: WILSON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A report was received via mPING of quarter size hail just west of Southland on the west side of the Lynn County line.

Hail in LUBBOCK, TEXAS
From 23-MAY-20 16:05:00 to 23-MAY-20 16:05:00 (CST-6)
Location: SLATON
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Scattered severe thunderstorms developed across Lubbock County on an outflow boundary. The first of these storms produced hail up to golf ball size from near Slaton to Buffalo Springs Lake at 1605 CST.

Thunderstorm Wind in LUBBOCK, TEXAS
From 23-MAY-20 16:06:00 to 23-MAY-20 16:18:00 (CST-6)
Location: LUBBOCK AIRPARK
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Scattered severe thunderstorms developed across Lubbock County on an outflow boundary. One of these storms produced a swath of severe winds from 1606 CST beginning at KCBD-TV studios. The swath of severe winds ended at the ASOS at Lubbock Preston Smith International Airport at 1618 CST. The initial wind gust at KCBD-TV was recorded at 62 mph while the ASOS recorded a 61 mph wind gust. Furthermore, the Lubbock County Sheriff's Office reported several power poles down along 98th Street from Indiana Avenue to US Highway 84 south of the initial wind report at KCBD-TV. The contract weather observer at Lubbock Preston Smith International Airport reported quarter size hail at the same time of the severe wind gust.

Thunderstorm Wind in GARZA, TEXAS
From 23-MAY-20 16:25:00 to 23-MAY-20 16:25:00 (CST-6)
Location: GRAHAM CHAPEL
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A Texas Tech University West Texas mesonet site near Graham measured a wind gust to 59 mph.

Hail in LUBBOCK, TEXAS
From 23-MAY-20 16:34:00 to 23-MAY-20 16:48:00 (CST-6)
Location: WOLFFORTH
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Scattered severe thunderstorms developed across Lubbock County on an outflow boundary. One of these thunderstorms produced severe hail on the western side of the city of Lubbock. Numerous reports were received of hail up to golf ball size from the southwestern portion of Lubbock through the western side of Lubbock. Hail up to two inches in diameter was reported in Woodrow. No damage was reported.

Thunderstorm Wind in HALE, TEXAS
From 23-MAY-20 16:42:00 to 23-MAY-20 16:46:00 (CST-6)
Location: SETH WARD
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A Texas Tech University West Texas mesonet site near Aiken measured a wind gust to 60 mph at 1642 CST and then 59 mph at 1646 CST.

Hail in LUBBOCK, TEXAS
From 23-MAY-20 17:19:00 to 23-MAY-20 17:19:00 (CST-6)
Location: WOLFFORTH
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Scattered severe thunderstorms developed across Lubbock County on an outflow boundary. One of these storms produced hail up to ping pong ball size in Wolfforth.

Hail in BRISCOE, TEXAS
From 23-MAY-20 17:22:00 to 23-MAY-20 17:23:00 (CST-6)
Location: SILVERTON
Magnitude: 3.25 
Reported by: Social Media

Several reports were received from social media and storm spotters of very large hail in Silverton. The largest hail size was estimated at 3.25 inches in diameter. Numerous vehicles were damaged by the hail.

Hail in HALE, TEXAS
From 23-MAY-20 17:09:00 to 23-MAY-20 17:09:00 (CST-6)
Location: PLAINVIEW
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A report was received via social media of quarter size hail in Plainview.

Thunderstorm Wind in SWISHER, TEXAS
From 23-MAY-20 17:30:00 to 23-MAY-20 17:30:00 (CST-6)
Location: TULIA
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A Texas Tech University West Texas mesonet site near Tulia measured a wind gust to 60 mph.

High Wind in BRISCOE, TEXAS
From 23-MAY-20 18:24:00 to 23-MAY-20 18:24:00 (CST-6)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in KENT, TEXAS
From 23-MAY-20 19:25:00 to 23-MAY-20 19:25:00 (CST-6)
Location: JAYTON
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A Texas Tech University West Texas mesonet site near Jayton measured a wind gust to 64 mph.

High Wind in CHILDRESS, TEXAS
From 23-MAY-20 19:35:00 to 23-MAY-20 19:35:00 (CST-6)
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Hail in LYNN, TEXAS
From 23-MAY-20 17:10:00 to 23-MAY-20 17:10:00 (CST-6)
Location: NEW HOME
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A spotter observed hail on the ground up to quarter size while driving through New Home. The time of the hail was estimated from radar data.

Tornado in GARZA, TEXAS
From 23-MAY-20 17:14:00 to 23-MAY-20 17:25:00 (CST-6)
Location: GRAHAM CHAPEL
Tornado F-scale: EFU
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A supercell thunderstorm became anchored over southwestern Garza County for a few hours. During the lifespan of this supercell, it produced a tornado which was widely captured by storm chasers. The time of the tornado reported by storm chasers was distinctly correlated with the strongest low level rotation from KLBB WSR-88D radar imagery. This tornado remained out over open land in southwestern Garza County between Farm to Market Road 669 and the edge of the caprock. Because of this, any damage was inaccessible due to lack of roads and therefore an EF-U rating was assigned.

Flash Flood in GARZA, TEXAS
From 23-MAY-20 17:00:00 to 23-MAY-20 19:00:00 (CST-6)
Location: GRAHAM CHAPEL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A supercell thunderstorm became anchored over southwestern Garza County for several hours. Heavy rains fell for an extended period of time which contributed to flash flooding over mostly rural areas of Garza County. Law enforcement reported that a portion of Farm to Market Road 669 south of Post was washed out. Additionally, water was running over US Highway 84 just southeast of Post.