A small but potent line of strong to severe thunderstorms dumped torrential rains, produced frequent lightning strikes, and slammed heavy winds across much of the Rio Grande Valley during the afternoon of April 28th.
A microburst powered up when it reached Cameron County, and ultimately caused significant damage to two poorly built mobile trailers in northern Los Fresnos. Surrounding damage in Olmito, Rancho Viejo, and other neighborhoods included dozens of snapped mesquite limbs, several uprooted trees, and at least one leaning power pole.
Heavy rainfall - the highest for any single event since January - dropped between 1 and 4 inches across portions of the Lower and Mid Valley. Pockets of urban and farm field flooding were noted as much of the rain fell within an hour and runoff or fast rising water was common.

Heavy Rain in HIDALGO, TEXAS
From 28-APR-13 11:20:00 to 28-APR-13 12:00:00 (CST-6)
Location: EDINBURG
Crop damage: 0.00K
Reported by: CoCoRaHS

Observed rainfall from Automated Weather Observation System platforms, CoCoRaHS observers, cooperative observers, and Emergency Management personnel of 1.4 to 1.8 inches in Edinburg, and between 2 and 4 inches in Mercedes - much of the rain falling in less than one hour - created nuisance urban and field flooding due to rapid runoff after months of very dry weather.  Up to 2 feet of water accumulated in poor drainage locations of Edinburg and Mercedes.

Heavy Rain in CAMERON, TEXAS
From 28-APR-13 12:15:00 to 28-APR-13 13:00:00 (CST-6)
Location: SANTA ROSA
Reported by: CoCoRaHS

Community Collaborative Rain, Hail, and Snow Network (CoCoRaHS), spotters, cooperative observers, and Automated Surface Observing Systems recorded between 2 and 3.5 inches of torrential rain in less than an hour, generally on a line from Santa Rosa to east of Cameron Park.  The torrents included much of Brownsville, Los Fresnos, and Harlingen.  At Brownsville (2.65 inches) and Harlingen/Valley Airport (2.37 inches), new daily records were set.  The heavy rainfall flooded previously parched farm and ranch fields with over a foot of water in some spots, particularly north of Los Fresnos, where the most rain (over 3 inches) fell.  Brief nuisance urban flooding was noted in Harlingen, portions of Brownsville, and Los Fresnos.

Thunderstorm Wind in HIDALGO, TEXAS
From 28-APR-13 11:20:00 to 28-APR-13 11:20:00 (CST-6)
Location: MC ALLEN
Magnitude: 42.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Broadcast media reported a tree blown down causing damage to a carport.  Nearby KMFE ASOS reported a 42 kt wind gust.

Thunderstorm Wind in CAMERON, TEXAS
From 28-APR-13 12:23:00 to 28-APR-13 12:32:00 (CST-6)
Location: LAURELES
Magnitude: 56.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

In North Los Fresnos, two tin roofs were lifted from old, poorly constructed trailers in a colonia neighborhood just east of the intersection of FM 510 and FM 1847 (Arroyo Blvd). Severe water and structural damage occurred at each residence; insulation was peeled from the roofs and some walls had cracked or collapsed. Both structures were uninhabitable. Nine persons were displaced.  Farther west along FM 510, a power pole was leaning at a 45 degree angle, and a mesquite tree was uprooted near the intersection of FM 803 and Henderson Road, about 4 miles to the southwest of the residential damage.

Thunderstorm Wind in CAMERON, TEXAS
From 28-APR-13 12:19:00 to 28-APR-13 12:25:00 (CST-6)
Location: RANCHO VIEJO
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: NWS Employee

NWS employee reported tree limbs blown down in Rancho Viejo. Wind gusts were estimated at 50 to 60 mph.  A few minutes later, estimated gusts to 60 mph lifted a trampoline into and over a fence, and bent other fencing material in North Brownsville.

Thunderstorm Wind in CAMERON, TEXAS
From 28-APR-13 12:25:00 to 28-APR-13 12:25:00 (CST-6)
Location: LA PALOMA
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: NWS Employee

A communication tower knocked was knocked down by strong winds near La Paloma.