A slow moving front, prior boundaries from evening storms on the 15th, and a warm humid air mass in place across the Rio Grande Valley activated numerous afternoon and early evening thunderstorms on April 16th. Early morning showers produced a funnel cloud in Donna; the tail of stronger storms which produced flooding, tornadoes, and hail across the Coastal Bend from mid-morning through mid-afternoon produced a small tornado on the Kenedy Ranch along the Kenedy/Kleberg County line.  By afternoon, temperatures warming into the mid and upper 80s were sufficient to trigger rapid development of thunderstorms in eastern Starr County; these would slide into Hidalgo County during the afternoon and produce a combination of torrential rains, frequent lightning, and hail mainly between pea and dime size with a few nickel and quarter size reports in the Edinburg/Pharr/McAllen area. More than 2 inches of welcome rain fell in Edinburg. By late afternoon, inflow of deep moisture along the Highway 77 corridor filled in thunderstorms between the Cameron/Willacy county line and the south end of the King Ranch. One storm grew very robust and slowly drifted in between Rio Hondo, Harlingen, San Benito, and Los Fresnos. An assumed large hail core centered over rural locations; others observed wind gusts to 55 mph and rainfall as much as 3.7 inches in Rio Hondo.
The outflow associated with the large storm in north central Cameron County outran its updraft support, and much of the action calmed by the time the remnants reached Brownsville between 5 and 545pm. The outflow combined with other boundaries from storms sliding along the Rio Grande River into southwest Cameron County to flare up a small but potent storm just west of Port Isabel just before 6 pm. As the storm raced east onto South Padre Island, a downburst developed which produced winds up to 57 mph at the Port Isabel Coast Guard station (along Laguna Vista Bay) and a half mile swath of estimated 70 to 75 mph winds across the central portion of the resort area of South Padre Island, all occurring roughly between 622 and 628 pm CDT. Reports from residents indicated two small boats sank at a bayside dock, two windows blown out of shuttle buses, a restaurant awning blown down, a utility pole knocked down at  service station, and lawn furniture strewn around one resident's yard.

Hail in HIDALGO, TEXAS
From 16-APR-12 14:53:00 to 16-APR-12 14:55:00 (CST-6)
Location: SAN JUAN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained Skywarn spotter reported quarter size hail in Pharr at the intersection of Hall Acres Road and Cage Boulevard.

Thunderstorm Wind in CAMERON, TEXAS
From 16-APR-12 17:22:00 to 16-APR-12 17:28:00 (CST-6)
Location: PORT ISABEL
Magnitude: 74.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

As the storm raced east onto South Padre Island, a downburst developed which produced winds up to 57 mph at the Port Isabel Coast Guard Station (along Laguna Vista Bay) and a 1/2 mile swath of estimated 70 to 75 mph winds across the central portion of the resort area of South Padre Island, all occurring roughly between 622 and 628 pm CDT. Reports from residents indicated two small boats sunk at a bayside dock, two winds blown out of shuttle buses, a restaurant awning blown down, a utility pole knocked down at a service station, and lawn furniture strewn around one resident's yard. Reports came from trained spotters and law enforcement.

Tornado in KENEDY, TEXAS
From 16-APR-12 07:37:00 to 16-APR-12 07:40:00 (CST-6)
Location: SARITA
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A tornado was reported on the Kenedy Ranch, approximately 3 miles south of Rivera (Kleberg County).  This storm would later produce a damaging tornado near Kingsville.  The National Weather Service Office in Corpus Christi relayed the report to from the general public.

Heavy Rain in CAMERON, TEXAS
From 16-APR-12 16:50:00 to 16-APR-12 16:57:00 (CST-6)
Location: BAYVIEW
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

An off-duty NWS employee reported an estimated 3 to 4 inches of rain along FM 510 near Bayview, with several inches of water flooding nearby roads.