How a confluence of time, geography and extreme timing has created the flood disaster in Texas

Although existing weather models can predict sudden floods in advance, even the best models have trouble representing the structure of internal storms and to predict where, a few kilometers, the most difficult precipitation will have the touch.

In this case, the colors out of the lanes on Friday morning indicated that the southern fork of the Guadalupe river took a direct and prolonged blow.

Then, instead of moving on, the storms stalled.

Texas state climatologist John Nielsen-Gammon said the thunderstorms hovered over the Texas Hill Country river, pouring 10-12 inches of precipitation in about six hours. The series of storms “perfectly aligned in the South Guadalupe river basin,” he said. The area is subject to floods and was filled with campers near the river. If the storm had even been five miles in another direction, that would not have produced so much destruction, he said.

It is difficult to know exactly how much rain has fallen. The pelvis that was flooded has no rain gauge despite an area covered by the Texmesonet surveillance system, which was created after a catastrophe of lightning floods that struck Wimberley, Texas, during the Memorial Day weekend in 2015. But the blind smell on Friday was a record for this place and a storm seen once every 1000 years, said Nielsen-Gammon.

While the forecasters of the National Weather Service had greatly warned sudden floods, meteorologists and forecast experts declared that the best weather models could not predict precisely where the most intense precipitation would fall, or that the deluge would address a basin subject to floods.

“Even the most detailed weather forecast models at this stage are barely capable of solving individual convection storms,” ​​said Nielsen-Gammon, adding that it would be “almost impossible” to predict well in advance if successive storms would train in the region, to take away and produce intense floods in such a confined geography.