An upper level disturbance, sandwiched between a receding upper level ridge across the southwest U.S. and another ridge across Florida and the eastern Gulf of Mexico, drew deep tropical moisture northward from the Bay of Campeche and points south. Meanwhile, a vigorous upper level disturbance across the upper midwest and associated frontal zone extending from the Great Lakes southwest into North Texas helped trigger a thunderstorm complex, which initially surge into the South Texas Plains overnight on the 21st. The complex set off boundaries which sparked intense storms along the Rio Grande and into northwest Tamaulipas and northern Nuevo Leon, M��xico, a little after daybreak on the 22nd. By early afternoon, the combination of the disturbance, daytime heating, advancing outflow from previous storms focused on the Lower Rio Grande Valley. Intense, slow moving thunderstorms formed from Mercedes/Weslaco northeast into Santa Rosa, Harlingen, and Raymondville. The storms would gradually weaken as they edged toward Brownsville.
On the 23rd, the surface low parked across Cameron County. Old boundaries, a pesky upper disturbance, and some heating into very unstable air triggered another round of tropical torrents from late morning through late afternoon. These rains inundated parts of the Lower Valley with 2 to 4 more inches of rain ��� some which fell in the same spots on the 22nd.
Two day rainfall totals ranged generally from 3 to 6 inches across the Lower Valley, with peak values in a swath bounded by Weslaco/Progresso northeast to Raymondville, then southeast to Brownsville.  Numerous instances of nuisance flooding, worse in areas where drainage was poor or debris had not been cleared from ditches or canals, were reported through the period.

Heavy Rain in HIDALGO, TEXAS
From 22-JUN-11 12:30:00 to 22-JUN-11 14:30:00 (CST-6)
Location: SHAYLAND
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Slow moving thunderstorms, containing up to an hour and a half of torrential rains, dumped between 3 and 4 inches across the heart of populated Hidalgo County, from Mission to Weslaco, during the early and mid afternoon of June 22nd.  Numerous instances of nuisance urban flooding were reported, much in the typical poor drainage locations that see flooding with any locally heavy rainfall.
Nuisance flooding of roads and ditches were reported in the typical poor drainage locations of McAllen/Pharr and Weslaco.  At McAllen/Miller airport, 3.13 inches of rain fell in less than two hours before the power was knocked out due to lightning in the area. CoCoRaHS observers reported 3.08 inches and 3.18 inches in Mission and Edinburg, respectively, and nearly 3 inches (2.84) fell at the Mid Valley Airport in Weslaco.

Flash Flood in HIDALGO, TEXAS
From 23-JUN-11 13:45:00 to 23-JUN-11 15:45:00 (CST-6)
Location: WESLACO
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The Weslaco/Donna Emergency Manager reported extensive flooding along both sides of Highway 83 (frontage roads along the expressway), as well as significant street flooding along Business 83 and Texas Boulevard (Farm to Market 88).  Local media reports indicated more than 2 feet of water in roads, some which impacted properties in town.  The flooding was caused by another round of torrential, tropical rains between 130 and 330 PM, which dropped more than 3 inches on top of the 2.84 inches which had fallen on the 22nd. More than 6 inches fell in Weslaco during the two day period.

Heavy Rain in CAMERON, TEXAS
From 23-JUN-11 11:15:00 to 23-JUN-11 14:15:00 (CST-6)
Location: (BRO)BROWNSVILLE ARP
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Deep tropical moisture worked on boundaries left over from showers and storms on June 22nd and into the early morning of June 23rd to produce locally heavy squally rains in the City of Brownsville during the early afternoon of June 23rd, adding another 2 to 3+ inches of rain to the somewhat lesser, but notable, totals from June 22nd.  Brownsville/SPI International Airport reported 3.52 inches of rain, and nearby CoCoRaHS observers recorded between 2.18 and 3.15 inches.
Urban flooding, particularly in the lower lying areas along Boca Chica Boulevard stretching downtown, developed through the afternoon before waters receded after 4 PM or so.  Significant damage was not reported despite the more than one foot of standing water in city streets.

Thunderstorm Wind in CAMERON, TEXAS
From 22-JUN-11 12:29:00 to 22-JUN-11 12:37:00 (CST-6)
Location: (HRL)RIO GRANDE ARPT
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

The ASOS platform at the Harlingen Valley International Airport recorded a wind gust of 66 miles per hour as a downburst moved through during a thunderstorm during the early afternoon. No damage was reported to the tower or on the field.

Heavy Rain in WILLACY, TEXAS
From 22-JUN-11 13:00:00 to 22-JUN-11 15:00:00 (CST-6)
Location: RAYMONDVILLE
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Slow moving thunderstorms, containing more than an hour of torrential rains, dumped between 3 and 6 inches in central Willacy County during the early and mid afternoon of June 22nd.  In Raymondville, up to a foot of standing water was observed by storm spotters and the county Emergency Manager; several roads were temporarily closed due to the urban/poor drainage flooding.  No water reached structures.  Observed rainfall ranged from just under 3 inches on the west side of Raymondville to 6.10 inches 6 miles east of Raymondville (San Perlita). Other minor flooding was reported in Sebastian (just north of the Cameron/Willacy County line), with backyards turning to low water lakes and streets with more than a foot of water in them.
The flooding in Sebastian intensified on the 23rd, reaching into properties as poor drainage structure in town (pipe structure) could not handle the heavy rains and flooding reached into the ground floor of a number of structures in town.

Lightning in WILLACY, TEXAS
From 22-JUN-11 13:55:00 to 22-JUN-11 14:15:00 (CST-6)
Location: RAYMONDVILLE
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Frequent cloud to ground lightning, particularly on the 22nd, caught a 400 barrel oil container on fire in Willacy County, and effects of another strike injured a woman attempting to enter her vehicle, all occurring around 3 PM CDT. The container fire was put out by the torrential rains; the woman was admitted to Valley Baptist Medical Center for observation.

Heavy Rain in CAMERON, TEXAS
From 22-JUN-11 13:00:00 to 22-JUN-11 15:45:00 (CST-6)
Location: SAN BENITO
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Slow moving thunderstorms, containing more than an hour of torrential rains, dumped between 3 and 5 inches in western Cameron County during the early and mid afternoon of June 22nd.  Numerous instances of nuisance urban flooding were reported, much in the typical poor drainage locations that see flooding with any locally heavy rainfall.
Across the Lower Valley, nuisance flooding of roads, ditches, and even some properties occurred each afternoon. On the 22nd, locally high water was reported in La Feria, Palm Valley/Harlingen, and San Benito. An estimated 5 inches of rain flooded the Mariposa subdivision near La Feria ��� an area which often has poor drainage issues and suffered greatly after Hurricane Dolly. The water rose to around 2 feet in neighborhood roads, closing them but not reaching into structures. On the west side of Harlingen, CoCoRaHS observers reported between 4 and 5.27 inches of rain.