When extremely heavy rainfall hit Texas and Oklahoma over the Memorial Day holiday weekend, Amateur Radio Emergency Service (ARES) and SKYWARN volunteers scrambled to assist local emergency operations centers and National Weather Service (NWS) offices.

“This has probably been the most significant weather event to hit Texas,” ARRL South Texas Section Manager Lee Cooper, W5LHC. “We have had major tropical storms and hurricane events, but the widespread combination of heavy rains, tornadoes, and flooding all at same time and covering two-thirds of the state, is pretty much unprecedented for us.”

Oklahoma Section Emergency Coordinator Mark Conklin, N7XYO, said communication systems in his state have, for the most part, remained unaffected by the flooding. “[There have been] no deployments or activations by any ARES-OK groups,” Conklin told ARRL. “All of the American Red Cross shelters are able to communicate via cell phone or normal land lines.”

Conklin said that ARES members in Leflore, Cherokee, Okmulgee, Tulsa, and several other Oklahoma counties have been busy on SKYWARN nets. “Members that also support local emergency management agencies have been busy passing information about storm damage and area flooding,” he added.

The fierce, torrential rainstorms were in stark contrast to the severe drought the region experienced in recent years. The floods they generated over the weekend struck with what Texas Gov Greg Abbott called “tsunami-type power.” The extreme flooding stranded hundreds and has resulted in several deaths. Abbott has declared a state of emergency in Texas and designated some three dozen counties as disaster areas.

The NWS-Houston Office posted a rare “flash flood emergency” warning, as the rainfall inundated highways, washing away or stranding countless vehicles. On May 24, the NWS confirmed than an EF1 tornado had touched down briefly in southwest Houston. At the peak of the rainfall on May 25, Houston was reported to have received nearly 1 foot of rain in less than 24 hours, comparable to the rainfall that might accompany a tropical storm or hurricane. Earlier in the holiday weekend, nearly the entire State of Texas was under a flash flood watch on May 23.

In Wimberly, Texas, a woman called her sister to report the family’s house was “floating down the river.” The home’s occupants are listed as missing. According to media accounts, water levels in Wimberly rose nearly 40 feet in a matter of hours.

The NWS has warned against driving vehicles through flooded areas and to use caution if walking near flooded waterways. “Do not try to wade or swim in flooded rivers and bayous,” the Weather Service added.

Exacerbating the situation were weeks of wet weather across the Southern Plains. The month of May is reported to have been the rainiest in the history of Oklahoma City, Fort Smith, Arkansas, and Wichita Falls, Texas. This month’s heavy rains have been linked to a burgeoning El Niño in the Pacific.