A slow-moving low pressure system drew in ample amounts of Gulf moisture on July 6th, allowing for very heavy rainfall to occur across portions of the Lower Rio Grande Valley. Several rounds of rain fell in Hidalgo and Willacy County, particularly in the town of Mercedes where a significant flash flooding event occurred, necessitating water rescues and several road closures.  In total, 6 to 10 inches fell in a swath from near La Joya (Hidalgo County) to the ranches of southeast Kenedy County, including much of the populated Rio Grande Valley north of Brownsville.

Flash Flood in HIDALGO, TEXAS
From 06-JUL-21 12:41:00 to 06-JUL-21 13:45:00 (CST-6)
Location: MERCEDES
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Report received via Broadcast Media of water completely covering lanes and shoulder on I-2/US-83 Eastbound near Mercedes. Lanes were closed as a result. Multiple water rescues eventually were needed. Video was also received via social media of water rising up to homes in the Mercedes area.

Flash Flood in HIDALGO, TEXAS
From 06-JUL-21 12:45:00 to 06-JUL-21 13:45:00 (CST-6)
Location: MERCEDES OLD REB ARP
Flood cause: Heavy Rain
Property damage: 75.00K
Crop damage: 0.00K
Reported by: NWS Employee

An NWS Employee reported water up to two feet deep resulting in stalled vehicles on the westbound Frontage Road near Rio Grande Valley Premium Outlets near Mercedes.

Flash Flood in WILLACY, TEXAS
From 06-JUL-21 13:00:00 to 06-JUL-21 14:00:00 (CST-6)
Location: PORT MANSFIELD
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: COOP Observer

A Co-Op Observer reported 5.8 inches of rain occurring between 10:30 AM and 2:00 PM, along with minor flooding in the Port Mansfield area. One house also experienced flooding.

Flash Flood in HIDALGO, TEXAS
From 06-JUL-21 11:10:00 to 06-JUL-21 12:00:00 (CST-6)
Location: MERCEDES
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Per public reports, numerous portions of a Frontage Road in Mercedes were flooded.

Flash Flood in HIDALGO, TEXAS
From 06-JUL-21 12:04:00 to 06-JUL-21 13:00:00 (CST-6)
Location: WESLACO
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reports received of water covering North Border Avenue near Weslaco High School.

Flash Flood in CAMERON, TEXAS
From 06-JUL-21 12:27:00 to 06-JUL-21 13:30:00 (CST-6)
Location: HARLINGEN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Local emergency managers reported standing water at the Intersection of Wilson Road and Frontage Road in Harlingen.

Flash Flood in HIDALGO, TEXAS
From 06-JUL-21 10:00:00 to 06-JUL-21 13:00:00 (CST-6)
Location: HAVANA
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: County Official

An official with the local Council of Government reported several feet of water on property next to her house, with over six inches of water inside her home north of La Joya. Total event rainfall exceeded 10 inches in this area over the course of several hours; additional flooding was also experienced in the area.