Hermine (2010)

A small tropical cyclone formed in the southern Bay of Campeche and was designated a tropical depression at 1800 UTC on 5 September 2010. It strengthened to Tropical Storm Hermine by 0600 UTC on 6 September and moved generally north to north-northwest across the western Gulf of Mexico. Hermine intensified as it approached the coast, made landfall early on 7 September, then moved northward across Texas into Oklahoma as a weakening system before degenerating to a remnant low and dissipating over southeastern Kansas by 0000 UTC 10 September.

Hermine made landfall on the northeastern coast of Mexico about 25 nautical miles south of Brownsville, Texas, near Matamoros, at 0200 UTC on 7 September. It was at its peak intensity at that time and then crossed into Texas, where it remained a tropical storm for about 16 hours after landfall while moving northward through the state.

The storm’s maximum sustained winds at peak were 60 knots (about 69 mph) with a minimum central pressure of 989 mb, corresponding to a strong tropical storm (below hurricane strength). The best-track record lists 60 kt at 0200 UTC 7 September as the peak intensity.

Storm surge along southeast Texas at landfall ranged roughly from 1.5 to 3.4 feet above normal tide levels, with higher local storm-tide measurements (for example, Port Lavaca recorded a storm surge/storm tide up to about 3.40 ft surge / 4.20 ft tide). Notable coastal observations include about 1.5 ft surge at South Padre Island and 1.61–1.73 ft at Port Isabel; Rockport and Bob Hall Pier saw storm surge values near 1.9–2.8 ft and storm tide up to about 4.13 ft at Bob Hall Pier. Hermine produced very heavy inland rains across central and southern Texas: the highest reported total was 16.37 inches at Georgetown Lake (7–9 September), with other totals including 14.56 in at Florence, 13.77 in at Cedar Park, and widespread double-digit amounts across the Austin area and parts of south-central Texas.

There were six confirmed deaths associated with Hermine: five in Texas and one in Oklahoma. Reported fatalities included one drowning in strong rip currents, two deaths while swimming in a flooded river, and three people washed off roads while driving around barricades. The storm downed trees and power lines in parts of southeastern Texas, produced tornadoes (including one near downtown Dallas causing significant building and warehouse damage and at least one injury), flooded many homes, and resulted in insured losses estimated at about $120 million; a commonly used doubling yields an estimated total damage of about $240 million.

Notable operational details: Hermine developed quickly from a disturbance first mentioned about 30 hours before formation, and the cyclone was relatively short-lived (about 72 hours). Forecast track errors were larger than recent averages, indicating the storm’s track was somewhat difficult to predict, but official intensity forecasts performed well for this system. Observations from buoys, coastal radar (including Alvarado, Mexico), and one reconnaissance flight, plus microwave satellite passes, were important for determining the storm’s position, intensity, and timing of landfall.