Damage to a gable end of a roof at a home in a colonia in San Carlos, east of Edinburg, TX. Downburst winds 60 to 65 mph took down the roof |
Two looped screen shots of radar base velocity at 0.5° elevation, or about 4000 feet above ground, that indicated winds of 60+ mph moving quickly south from west of Hargill to San Carlos in Hidalgo County, TX, between 535 and 555 PM May 14th, 2016 |
A Week of Hazardous Weather, May 14 to 20, 2016 RGV, Ranchlands Face Big Hail, Big Wind, and some Big Rain |
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Short survey of structure, tree, and power line damage from west of Hargill to San Carlos, TX, from May 14, 2016 downburst. Click to download the data in Google Earth. Need Google Earth? Click here After a quiet start to May, which featured a refreshing front on May 1st that brought drier days and pleasant nights right into the Mother’s Day Weekend, the pattern shifted back to a trough centered over the southwest U.S. (below) that ejected ripples of energy eastward, beginning by mid month. Starting on the second weekend of May and finally taking a break by May 21st, these ripples enhanced southerly flow and pulled tropical moisture into Texas, which was lifted into thunderstorms that produced significant rainfall, hailstorms, and damaging wind across the Rio Grande Valley, South Texas Brush Country, and Coastal Bend. May 14 through 18: Mixed Bag, Favoring Wind and Hail On Sunday, May 15th, leftover boundaries from the Saturday storms acted on plenty of residual heat and humidity to kick off scattered late morning through late afternoon activity, which favored the Lower and Mid Valley and extended through the King Ranch. The additional rain exacerbated nuisance flooding in the colonias that received nearly 3 inches the prior day, and peaked with more than 4 inches that caused urban flooding around Harlingen during the mid afternoon. The biggest rains that afternoon and overnight struck the Coastal Bend, where more than a foot fell and flooding was widespread and property–damaging. 500 millibar (~18,000 feet) steering pattern for May 14 through 21, 2016. Upper level disturbances moving along the purple arrow helped lift a deep feed of moisture from the tropics into strong to severe thunderstorms across much of south Texas. |
May 14 through 18: Mixed Bag, Favoring Wind and Hail (continued) Typically, overnight storms "work over" the atmosphere and bring a quieter day to follow. Because the main system formed in Mexico, remaining boundaries and a oppressively warm, humid day combined with another weak disturbance to create a long track, mini–supercell storm that zipped across the Rio Grande Plains and rural ranchlands from Zapata through Kenedy County during the early and mid afternoon of the 18th. Though no reports of large hail and damaging winds were received, the storm did produce frequent to excessive lightning along its path and may well have produced some hail and wind before fading into the Gulf. May 20: Slow Moving Thunderstorm Floods South Mission Photo from South Mission during evening of Friday, May 20th, showing urban type flooding. Courtesy of KRGV Channel 5 Facebook page, shared with NWS Brownsville/Rio Grande Valley’s Facebook page. Screenshot of Advanced Hydrologic Prediction System bias corrected rainfall estimate for May 20th, 2016, zoomed into Hidalgo County. Six inches was estimated over a rural area near the levee protected Rio Grande.
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