McALLEN, Texas (Border Report) — Tropical Storm Alberto became the first named storm of the 2024 hurricane season on Wednesday as the system, located off the coast of Mexico, was bringing much-needed rain to the South Texas border and prompting some coastal flooding threats.

The core area of Tropical Storm Alberto on Wednesday morning remained over 300 miles southeast of Brownsville, Texas, in the Gulf of Mexico, but bands of welcome rain were already coming through in waves to the Rio Grande Valley, which has been in a drought.

Between 3 and 6 inches of rain are expected on Wednesday in cities from Brownsville to McAllen, with upwards of 7 inches expected by the time the system rolls through the region on Thursday, according to NBC23 Valley Storm Team Meteorologist Jessica Kirk.

Winds of 39 to 57 mph could accompany the storm as it sends moisture throughout the region, Kirk said.

Tropical storm warnings were issued for the Gulf Coast counties of Cameron and Willacy.

By 10:30 a.m. CT, the system was centered over the Gulf of Mexico, and was expected to make landfall Wednesday night or overnight near Tampico, Mexico.

But the system is vast and wide and spread out over hundreds of miles, bringing rain to most of the Texas coast, including Corpus Christi where coastal flooding was already occuring.

The South Texas border city of Laredo, over 200 miles west of Brownsville, was also bracing for heavy rains, which could possibly double its total rainfall this year to date.

Laredo is in Stage 3 water conservation restrictions due to an ongoing drought and the city feared it will run out of drinking water, which it gets 100% from the Rio Grande.

The Rio Grande has been shrinking due to excessive triple-digit heat that has hit the region for weeks, as well as Mexico’s lack of water payments to the United States.

Under a 1944 international water treaty, Mexico is supposed to pay the Rio Grande 1.2 million acre-feet of water during a 5-year cycle. The current cycle ends in October 2025, but Mexico has paid less than 400,000 acre feet of water and there is just a little over a year left in the current cycle, according to the U.S. Section of the International Boundary and Water Commission.

Under the treaty, the United States is entitled to one-third of the flows of the Rio Conchos and other tributaries that run from mountains outside Chihuahua, Mexico, into the Rio Grande. An acre-foot is the water needed to cover 1 acre in 1 foot of water, or about 326,000 gallons.

The two regional water reservoirs were at historic lows on Wednesday. Amistad Reservoir was below 19% and Falcon Reservoir was at 9.4%, according to IBWC data.

If this tropical storm system settles southwest of Laredo, that could really replenish the tributaries that feed into the Rio Grande and the reservoirs, experts say.

Laredo leaders are preparing and studying alternative methods for water supplies in the future. They expect their water supply to run out by 2044 if additional sources are not found.

In Hidalgo County, a drought disaster was declared in April.

This came after the state’s only sugar mill was forced to close down in February in Santa Rosa, Texas, because growers didn’t have enough water to produce the thirsty crops.

In anticipation of the storm, several cities in the Rio Grande Valley were offering free sandbags to residents.

Nearly 3,000 power outages were reported Wednesday in Hidalgo County and Cameron Cameron, on the Gulf coast, according to ValleyCentral.com.

Several school districts were closed on Wednesday, including Brownsville ISD, Donna ISD, Weslaco ISD and McAllen ISD.

Sandra Sanchez can be reached at SSanchez@BorderReport.com.