A weak upper level disturbance rotating around high pressure across the Deep South combined with very warm and humid air to produce scattered to numerous late afternoon thunderstorms across the Lower Rio Grande Valley on April 16th, some which produced flooding rains.  Another round of scattered storms developed during the mid afternoon of the 17th near the coast. These storms set off boundaries which collided with other boundaries moving southwest from the Coastal Bend, ultimately feeding a cluster of strong to severe storms in Hidalgo County which produced a combination of flooding, hail, frequent lightning, and gusty winds during the evening.

Flash Flood in CAMERON, TEXAS
From 16-APR-10 17:00:00 to 16-APR-10 18:00:00 (CST-6)
Location: HARLINGEN
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Pendleton Park and City Park in Harlingen was under water. One lane of North Farm to Market Loop 499 was closed. Local newspapers reported water surging through city streets between 6 and 7 PM. Power was knocked out at Valley International Airport from 7 until around 830 PM from unknown causes related to the storm.  A daily record of 2.77 inches of rain fell in a very short time at Valley International Airport; radar estimates suggested 3 to 4 inches fell in areas which flooded.

Thunderstorm Wind in HIDALGO, TEXAS
From 17-APR-10 18:45:00 to 17-APR-10 18:45:00 (CST-6)
Location: MISSION
Magnitude: 52.00 EG
Crop damage: 0.00K
Reported by: Law Enforcement

Wind Gust measured in the City of Mission.

Hail in HIDALGO, TEXAS
From 17-APR-10 18:55:00 to 17-APR-10 19:03:00 (CST-6)
Location: SHAYLAND
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Quarter sized hail was reported in Mission in two locations along or near Griffin Road (FM 495): At the intersection of Griffin and Glasscock, and just north of Griffin on Bryan Road.  Events occurred between 755 PM and 803 PM CDT.

Flash Flood in HIDALGO, TEXAS
From 17-APR-10 18:30:00 to 17-APR-10 19:30:00 (CST-6)
Location: PALMHURST
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Rainfall of more than 4 inches in a little more than an hour produced flash flooding from Mission to McAllen between 730 and 830 PM. Local television news reported one home with water flooding the ground floor, and vehicles submerged, in Mission, from a combination of poor drainage and the blinding rains. Floodwaters covered a driveway, reaching the garage of a home on Highland Park Ave. in Mission. State Road 107 and Farm to Market 495 each were closed with up to 2 feet of water covering them. Flooding on the frontage road of Expressway 83 between 23rd Avenue and Ware Road produced water up to the windshields of dozens of cars in McAllen. Rainfall reached 2.46 inches in McAllen/Miller Airport, 3.40 inches at the nearby cooperative station, 3.74 inches in Mission, and 4.08 inches just northeast of Mission, all falling in a little more than an hour. The aftermath of the frontage road flooding was documented by video posted on YouTube.  View the video at http://www.youtube.com/watch?v=6viYuz8VBW8 .

Heavy Rain in CAMERON, TEXAS
From 17-APR-10 14:45:00 to 17-APR-10 15:15:00 (CST-6)
Location: EVAN
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy rainfall left 1 to 1 1/2 feet of water along Paredes Line Road, between Paseo Plaza near the intersection of Ruben Torres Blvd. (FM 802) and just north of CSR Blvd. and the Emerald Valley subdivision.  Storm estimated rainfall, which was very localized, was 2.5 inches.  Boundaries from these storms would later feed into more significant activity in Hidalgo County during the evening.