Drier weather to close out month; reservoirs still very low in South Texas

The recent showers have done little to relieve current drought conditions

A shell sits on the dry shore at Falcon Lake on July 28, 2022, in Zapata County. (Delcia Lopez | [email protected])

Recent rains over the last month have removed drought conditions throughout the Rio Grande Valley and the deep South Texas Ranch and Brush Country, according to the National Weather Service in Brownsville.

In an email, Barry S. Goldsmith, NWS warning coordination meteorologist, said that despite the improvements, the Valley can expect some drier-than-average weather for the latter half of the month.

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“The latest three-month outlook for October-December has been issued by the Climate Prediction Center; we’ll have our local interpretation of this outlook next week with additional updates to both rainfall and reservoir information,” Goldsmith said in the email.

“Bottom Lines? While reservoir levels have responded to the rains of the past month, they are still on the low to very low side of the historical record,” he continued. “And, drought improvement is likely to be fleeting for at least some of the area as we move deeper into autumn – including December and beyond.”

In the email, Goldsmith said that Amistad Reservoir and Falcon International Reservoir both benefited from the August and mid-September rain.

“Reservoirs/lakes along the Rio Conchos rose sharply from very low levels to over 100% capacity in just a few weeks (attached), prompting releases of significant water downstream and into the Rio Grande across the Texas Big Bend,” the email read. “Lake Luis Leon surged from 12 percent on August 15th to 163 percent of capacity on September 15th. Additional flow from upstream (including the Devils and the Rio Grande from El Paso eastward) are combining with the Rio Conchos flows to create a steady rise at Amistad.”

Goldsmith said that water levels are expected to continue to rise into the month of October, with the total percentage of water from the United States and Mexico exceeding 40% before leveling off.

A small island rises above the water at Falcon Lake on July 28, 2022, in Zapata County. (Delcia Lopez | [email protected])

Despite the higher water levels, he said that they will still be well below the historical average.

“Falcon also benefited from a combination of multiple mini ‘flood waves’ moving down the Rio Grande between Del Rio and the northern entrance of the lake from mid August into early September,” the email read. “Unlike Amistad, however, tributary inflows from Mexico have stopped since early this week, and conservation storage values have leveled off, close to 19 percent (up from 10.75% on August 13-15).”

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With the forecast through December suggesting limited additional rainfall, Falcon Reservoir will most likely see a resumption of slow declines in water storage levels beginning as early as October.

“The combined Amistad minus Falcon water storage rose from 20.7% at its mid-August minimum to 26.2% this week,” the email read. “Additional gradual rises are expected over the next few weeks, largely due to inflows arriving into Amistad from the Conchos and Rio Grande upstream. Expect the rises to level off later this autumn.”

The next eight to 14-day forecast shows hotter and drier than average conditions for the Valley and the Rio Grande Basin — a sharp contrast from the previous week of Sep. 11 through Sep. 17, which was among the wettest on average with regional rainfall averaging 1.2 and 2.5 inches throughout the Valley.

“Rainfall activity that we saw Wednesday and Thursday (14th and 15th) is quite “normal” for this time of year,” the email read. “Only modest rainfall is expected for the next week (September 17-23), and likely to be below that week’s climatological average.”

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