Credit: San Antonio Express-News
On the weekend of October 17 to 18, 1998, a pair of hurricanes over the Eastern Pacific and a near stationary cold front led to disastrous flash flooding along the Guadalupe River and over the San Antonio metro area. When heavy rains began on the morning of October 17, mid to high level moisture from the weakened remnants of Hurricane Madeline was crossing the Sierra Madre Occidental into central Texas. Meanwhile, low-level and mid-level moisture on the outer periphery of Hurricane Lester in South of Acapulco was moving across the Isthmus of Tehuantepec and up the western coast of the Gulf of Mexico toward south Texas.
A cold front was expected to provide the focusing mechanism for the heavy rains, but torrential rains began to develop along the Balcones Escarpment in the early morning hours on Saturday, October 17--well ahead of the cold front. Convection developed into a nearly stationary Mesoscale Convective System (MCS) which impacted communities along the Balcones Escarpment from San Antonio to Austin with almost continuous rainfall for up to 36 hours. By Saturday afternoon, homes along the Guadalupe River from Canyon Lake to Seguin were being washed off their foundations. Over 30 inches of rain was estimated over a small area south of San Marcos in 36-hours. As the storm complex inched slowly east and south, heavy rains of 5 to 15 inches covered downstream portions of southeast Texas and the Coastal Bend Saturday night into Sunday, right as the upstream flood waves were beginning to move into those areas. Especially hard hit among the downstream communities was the town of Cuero, which saw its downtown area inundated by diverted floodwaters that were over 2.5 miles away from the main Guadalupe River channel.
The most rain recorded on any calendar day in San Antonio occurred Saturday, Oct. 17, 1998 when 11.26 inches of rain fell at the San Antonio International Airport. At that time this broke the record of 6.83 inches on September 9th, 1921. It also shattered the previous record for October 17, which was 2.13 inches in 1948. The most rainfall in a 24 hour period of 13.35 inches occurred in 1998 from October 17-18.
1998 was the wettest month of any month and wettest October of record, with 18.07 inches of rain. At that time the previous record wettest month of any month was 15.78 inches in Sep. 1946. At that time the previous wettest October was 9.74 inches in 1994.
For October 1998 Austin received 12.39 inches of rain making October 1998. This is the 3rd wettest October on record for the Austin City climate location. On October 17th, 6.24 inches of rain fell at the Robert Mueller Airport in Austin. This broke the old record for October 17th of 2.48 inches set back in 1937.
Austin Bergstrom International Airport received 6.89 inches of rain on October 17th 1998. For the Austin Bergstrom location, the 12.73 inches in October 1998 was at that time the 2nd wettest October.
The Guadalupe-Blanco River Authority (GBRA) posted some overhead video of rivers after the damage on their website.
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