Slow‑Moving Storms Raise Flash‑Flood Threat Across Central and South Texas
Bands of moisture‑rich, slow‑moving thunderstorms are producing 2–3+ inch‑per‑hour rainfall that could yield localized 2–5+ inch totals, posing a flash‑flood threat to vulnerable urban and low‑lying areas.
Overview
- Forecasters warned late Wednesday that scattered storms in western and central Texas could merge and train over the Hill Country, producing 2 inch‑per‑hour rates that make isolated flash flooding likely in sensitive spots.
- Thunderstorm clusters moving north from Mexico into the Lower Rio Grande Valley produced 2+ inch‑per‑hour rates overnight and were expected to bring localized 2–4 inch totals with isolated 5 inch amounts possible.
- A mature mesoscale convective system along the middle Texas coast produced very efficient rainfall near 3 inches per hour Thursday morning and forecasters said local 5+ inch totals could not be ruled out.
- The Storm Prediction Center noted extremely high instability with pockets of MUCAPE up to about 4,000 J/kg, saying an isolated damaging wind or hail report is possible but a broader severe outbreak or watch is unlikely.
- Forecasters cited strong low‑level moisture transport, slow storm motion, and storm mergers as the main drivers of flood risk and urged local offices and river forecasters to monitor urban centers, Llano, and the Austin area for flash flooding.