Photos taken from damage survey of Laureles/North Los Fresnos/North Brownsville, April 28th 2013
Rain, Wonderful Rain!
Thunderstorms Soak the Lower Valley; Lightning and Wind Cause Damage and Outages

Much More Needed to Dent Drought
Points where damage to poorly constructed buildings and roofs was surveyed
Map of notable surveyed damage in and near Laureles, Texas, from microburst winds on April 28th, 2013.

Event
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. Hazards and impacts included:

  • Rain. Two to nearly four inches pounded most cities and towns east of Highway 281. Rainfall rates as hjigh as 1.5" in 20 minutes during the primary storm, which occurred in half hour intervals between noon (McAllen/Edinburg) and 2 PM (Port Isabel/South Padre) reduced visibility to near zero, left up to two feet of floodwaters in the usual poor drainage locations, and soaked thirsty fields and pastures.
    • At Harlingen/Valley International Airport, the 2.37 inches destroyed the previous April 28th record of 1.13 inches set in the late 1950s. The single day total was the highest since September 19th, 2010, when 3.04 inches fell!
    • At Brownsville/South Padre Island International Airport, 2.65 inches set a new daily record, besting the 2.43 inches that fell in 1989. This was the highest single day total since August 6th, 2012, when 3.08 inches fell.
    • At McAllen/Miller International Airport, 1.12 inches fell, the largest single day total since October 18th, 2012, when 1.37 inches fell
  • Lightning. Frequent cloud to ground strikes contributed to thousands of power outages across Hidalgo and Cameron County. AEP Texas, which serves much of Cameron and Hidalgo County, reported more than 10 thousand customers without power near the peak of the storm in Hidalgo, and nearly 7 thousand in Cameron. Brownsville Public Utilies Board (PUB) reported 1,200 persons without power, including the University of Texas at Brownsville Campus.
  • Wind. A swath of very strong winds accompanied the squall line through eastern Hidalgo, Cameron, and southern Willacy County. Peak gusts included:
    • 53 mph at Bayview/Cameron County Airport.
    • 51 mph at Harlingen/Valley International Airport.
    • 48 mph at McAllen/Miller International Airport
    • 44 mph at Edinburg International Airport
    • 40 mph at Brownsville/South Padre Island International Airport and at South Padre Island Heliport.
    • 31 mph at Weslaco/Mid Valley Airport.
  • Wind Damage. The microburst powered up when it reached Cameron County, and ultimately caused significant damage to two poorly built mobile trailers in North Los Fresnos (locations shown above). 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. The tale of the tape:
    • Peak Wind Speed (estimated by survey): 60 to 65 mph.
    • Time of Peak Speed: 125 PM, both in Los Fresnos and North Brownsville
    • Damage Details: In North Los Fresnos, two tin roofs were lifted from old, poorly constructed trailers. 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. In North Brownsville, a trampoline was lofted into and over a fence before landing on the other side of a thoroughfare.

 

Meteorology
An upper level disturbance helped induce a weak low pressure system in the lee of the northern Sierra Madre mountains. Strengthening southeast winds combined with the disturbance and old boundaries from thunderstorms overnight on the 27th to produce the first widespread, locally heavy rainfall event for the Rio Grande Valley since January 8th and 9th, a span of more than three months! Rainfall generally ranged from 1 to 3 inches. Higher values, 3 to nearly 4 inches, fell in a swath from near Mercedes (southeast Hidalgo County) through San Benito and Harlingen (Table and map, below). A second swath of an estimated two inches or more covered portions of the Jim Hogg County ranchlands, in two batches; one overnight on the 27th, and a second early on the 28th.

Soon after daybreak on the 28th, the ranchland storms organized into a brief but potent squall line that moved from Zapata through Starr County. The line disintegrated into disorganized and weaker clusters by late morning while moving through eastern Starr and western Hidalgo County, then reloaded into a formidable line of torrential rainfall, frequent cloud to ground lightning, and enhanced downburst winds around noon. The line crossed the vast majority of the populated Rio Grande Valley between noon and 230 PM, and produced urban flooding in all poor drainage locations from Edinburg to Brownsville. As the storms crossed into Cameron County, individual bow–shaped structures (bottom of page) surged toward the coast. Radar indicated cores suggested 60 mph or greater winds just above the surface, some of which translated into an area of minor damage to trees and limbs, and at least two ripped off roofs north of Los Fresnos.

Drought...Out?
One could only dream.

It will take many more events like these to remove the Extreme to Exceptional drought conditions that have built up over more than 2 and ½ years! And, those events would need to be spaced much closer together than ones that have already occurred during the current record drought. Just to refresh the memory, a partial list of wet periods embedded within the drought which began in October 2010:

 

Would this be just another in the series of infrequent, but helpful, rain events in a desert of dry weather? As of this writing, long range models through mid May suggested a return to largely rain free weather with temperatures gradually warning toward the expected swelter that arrives thereafter. The longer term forecast of eventual searing heat, and a "lean" toward lower rainfall totals, remained intact.

Falcon Dam snapshot, afternoon of April 29th, 2013, showing slight increases from rainfall of April 27/28
Falcon International Reservoir conservation level as of 2 PM CDT, April 29th. Slight increase (circled area, right) was due to a combination of releases of water from Amistad International Reservoir, which reached record lows on April 26th, 2013, and heavy rainfall along and west of the Rio Grande near Laredo on April 27th.
Rainfall for the Rio Grande Valley/Deep South Texas, April 27 and 28, 2013
Note: Dashed area in Jim Hogg and extreme northern Starr County is based on bias corrected radar estimates.

Rainfall data from 7 PM April 27th through 7 AM April 29th
City/Town
County
Report Type
Rainfall
San Benito 0.6 miles SSE
Cameron
CoCoRaHS
3.70
Harlingen 4.3 miles WSW
Cameron
CoCoRaHS
3.53
Harlingen 4.7 miles WSW
Cameron
CoCoRaHS
3.52
Brownsville 6.4 miles WNW
Cameron
CoCoRaHS
3.33
Rancho Viejo 3.0 miles SE
Cameron
CoCoRaHS
3.19
Brownsville 1.9 miles ESE
Cameron
CoCoRaHS
3.08
Brownsville 5.0 miles NNW
Cameron
CoCoRaHS
3.07
Harlingen
Cameron
Cooperative
3.01
Los Fresnos 0.3 miles NE
Cameron
CoCoRaHS
2.99
Harlingen 2.6 miles ESE
Cameron
CoCoRaHS
2.95
Brownsville 0.1 miles SSE
Cameron
CoCoRaHS
2.76
Rancho Viejo 0.7 miles E
Cameron
CoCoRaHS
2.73
Brownsville/South Padre Island Int'l Airport
Cameron
ASOS
2.70
Weslaco/Mid Valley Airport
Hidalgo
AWOS
2.70
Brownsville 4.1 miles ENE
Cameron
CoCoRaHS
2.63
Brownsville 4.1 miles E
Cameron
CoCoRaHS
2.61
Brownsville 2.3 miles NW
Cameron
CoCoRaHS
2.60
Falcon Lake
Starr
RAWS
2.60
Raymondville
Willacy
Cooperative
2.59
Brownsville 6.4 miles SE (Sabal Palms)
Cameron
CoCoRaHS
2.54
Harlingen/Valley International Airport
Cameron
ASOS
2.37
Brownsville 4.2 miles NE
Cameron
CoCoRaHS
2.37
San Benito 7.8 miles E
Cameron
CoCoRaHS
2.35
La Feria 1.3 miles ENE
Cameron
CoCoRaHS
2.29
Raymondville 2.0 miles SSW
Willacy
CoCoRaHS
2.26
Lower Rio Grande Valley NWR/Santa Ana
Hidalgo
RAWS
2.22
Brownsville 2.2 miles W
Cameron
CoCoRaHS
2.18
Brownsville 4.4 miles NE
Cameron
CoCoRaHS
2.11
Lower Rio Grande Valley NWR/Linn-San Manuel
Hidalgo
RAWS
1.89
San Manuel
Hidalgo
Cooperative
1.80
Rio Grande City 17.7 miles NE
Starr
CoCoRaHS
1.80
Edinburg 0.8 miles ENE
Hidalgo
CoCoRaHS
1.79
South Padre Island 1.1 miles N
Cameron
CoCoRaHS
1.71
La Joya 11.1 miles N
Hidalgo
CoCoRaHS
1.70
Laredo Int'l Airport
Webb
ASOS
1.69
Hebbronville
Jim Hogg
Cooperative
1.64
Hebbronville
Jim Hogg
RAWS
1.63
Rio Grande City 13.8 miles NNW
Starr
CoCoRaHS
1.60
Zapata/Medina County Airport
Zapata
AWOS
1.53
Edinburg
Hidalgo
Cooperative
1.50
Jim Hogg County Airport
Jim Hogg
AWOS
1.44
Laguna Atascosa NWR
Cameron
RAWS
1.43
Port Isabel
Cameron
Cooperative
1.40
Edinburg International Airport
Hidalgo
AWOS
1.40
Bayview/Cameron County Airport
Cameron
ASOS
1.27
Falfurrias 8.9 miles SSW
Brooks
CoCoRaHS
1.25
Falfurrias 0.5 miles WNW
Brooks
CoCoRaHS
1.23
Falfurrias
Brooks
AWOS
1.20
Port Mansfield
Willacy
Cooperative
1.15
McAllen 2.4 miles NE
Hidalgo
CoCoRaHS
1.14
McAllen/Miller Airport
Hidalgo
ASOS
1.12
Hebbronville 17.6 miles WSW
Jim Hogg
CoCoRaHS
1.11
McAllen
Hidalgo
Cooperative
1.02
Mission 1.9 miles ENE
Hidalgo
CoCoRaHS
0.97
Falcon Dam
Starr
Cooperative
0.96
Sarita 7 miles E
Kenedy
Cooperative
0.90
Rio Grande City 2.8 miles W
Starr
CoCoRaHS
0.87
La Joya
Hidalgo
Cooperative
0.80
Brooks County Airport
Brooks
AWOS
0.74
Alamo 1.5 miles NNE
Hidalgo
CoCoRaHS
0.72

*AWOS = Automated Weather Observing System
*ASOS = Automated Surface Observing System
*CoCoRaHS = Community Collaborative Rain, Hail, and Snow Network
*Cooperative = Cooperative Climate Network
*RAWS = Remote Automated Weather System


Radar loop of base velocity at 0.5° elevation across Cameron County, from 108 to 206 PM CDT, April 28th 2013. Blue splotches surging through Rancho Viejo/North Brownsville, and soon after Los Fresnos/Bayview, indicate 58 to 67 mph winds between 500 and 1000 feet above ground. Click to enlarge.

Radar loop of base reflectivity at 0.5° elevation across Cameron County, from 108 to 206 PM CDT, April 28th, 2013. Click to enlarge.

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