Flash Flooding in Texas, October 17 to 19, 1998

The Great October FloodIn advance of a very slow-moving upper level trough of low pressure over West Texas, a cold front drifted slowly southeastward into West Central Texas during the evening of Friday, October 16th. Deep moisture was in place across South Central Texas as the two systems approached, being fed at the mid and upper levels by two nearly stationary hurricanes, Madeline near the tip of Baja Mexico, and Lester, anchored just off Acapulco, Mexico, and in the low levels by a strong flow from the Gulf of Mexico. A very moisture-rich environment was in place across South Central Texas as the event developed. Near 3 am CST, with the cold front still west of San Angelo, scattered showers and thunderstorms began to break out over Bexar County beneath the mid and upper level moisture plume. They quickly became widespread as a low level rain-cooled boundary formed along the south and east edge of the county. It was upon this boundary that subsequent showers and thunderstorms continued to form. By 6 am CST, rainfall of up to 4 inches had been reported in Western Bexar County, with amounts approaching 4 inches in Western Comal County. By 8 am CST that morning, heavy rain continued over Bexar County, and had spread northward across Comal County into Hays, Travis and Williamson Counties. Amounts at this time were approaching 8 inches in Bexar and Comal Counties and 4 inches in Hays and Travis Counties. The heavy rain continued through the morning period. Shortly before noon on Saturday, heavy rain began to spread eastward into Guadalupe, Caldwell, Bastrop and Lee Counties. Through the mid afternoon, moderate to heavy rain continued between San Antonio and Austin, with widespread heavy rain over Comal, Hays, Caldwell, Guadalupe and Gonzales Counties. By 5 pm CST, the strongest low level flow had also shifted eastward, focusing the heaviest rainfall through the evening period over the area from LaGrange to Gonzales to Karnes City to Cuero and Hallettsville. By midnight, heavy rain had exited the Cuero-Hallettsville area, and moderate rain had again broken out over Bexar and Comal Counties. The activity spread westward through the early morning hours on Sunday to Hondo and Uvalde and northwestward into the Hill Country. At the same time, moderate to heavy rain also redeveloped along and north of a line from San Antonio to Gonzales to LaGrange. By late Sunday morning, the cold front moved through South Central Texas, and had slowed and stalled as it approached the Lower Texas Coast. Spotty heavy rainfall continued in the wake of the front between San Antonio, Burnet and Bastrop as another weak upper level disturbance in the southwesterly flow aloft approached. Heavy rain also developed along the front, just north of Laredo and along the coastal plains from Corpus Christi to Victoria. Even though rainfall amounts in the San Antonio to New Braunfels to San Marcos to Austin corridor were generally below 2 inches on Sunday, soils remained saturated from the previous day's deluge and periods of flash flooding were reported through the mid morning.By Sunday afternoon, rain had diminished in the San Antonio to Austin corridor, while clouds, rain and frequent showers continued east of the area. Thereafter, rainfall was generally along and east of a LaGrange-Gonzales-Karnes City line, where an additional 3 to 5 inches of rain fell on Sunday and 2 to 4 inches fell on Monday. Only scattered light rain was reported on Tuesday and Wednesday, the 20th and 21st of October.All rivers, creeks and streams along and east of a San Antonio to Austin line remained at or above flood stage from Saturday, October 17th through Sunday, October 18th, with a majority continuing to flood through Monday, October 19th. On Tuesday, October 20th and Wednesday, October 21st,flooding was confined to rivers, streams and creeks along and east of a LaGrange-Gonzales-Karnes City line. This event broke rainfall records across South Central Texas, producing 18 floods of record in South Central Texas streams. October became the wettest of any month in climate records for San Antonio since 1885. October 17th became the wettest day and wettest 24-hour period in San Antonio climatic records, nearly doubling both previous records. Rivers across the area reached or exceeded record stage heights, resulting in widespread flooding in the flood plains of streams, creeks and rivers. Rainfall amounts on October 17 and 18th from northern Bexar County to southeast Kendall County, most of Comal County and southern Hays County ranged from 15 to 22 inches. Damage and destruction to livestock and agriculture, roads and bridges and both public and property and buildings significantly exceeded that of previous flooding. Thousands to tens of thousands of livestock were killed, as nearly 3000 homes were destroyed and another 8000 or so homes were damaged. Nearly 1000 mobile homes were destroyed and another 3000 were damaged.Twenty-five people drowned as a direct result of the flooding in October in South Central Texas. All nine deaths in Bexar County on Saturday, as well as the two on Sunday, were associated with driving vehicles into flooded waters. Four of the six Caldwell County deaths, two of the three Guadalupe County deaths, and all of the four deaths in Comal, Travis and Uvalde County were associated with vehicles as well. Two deaths in Caldwell County and one in Guadalupe County occurred as residents were swept by flood waters from their homes. In addition, one man in Comal County suffered a heart attack and died waiting to be rescued and another died of a heart attack while being rescued. A third man in Guadalupe County accidently touched a live wire while in his boat. He was severely shocked and died from drowning as a result of the shock.