Technical Reports Document Library

2004 marked the third year of operations for the Edwards Aquifer Authority (EAA) by the STWMA. As was the case in 2002 and 2003, one plane, N57AA, was stationed at Stinson Field (SSF) in south San Antonio. Two of our pilots, Ron Merks and Mickey Chadwell, were stationed there. They worked along with Jim Transue and Tim Pickens, stationed at Pleasanton, and Larry Dement, stationed at Kenedy. Occasionally the other pilots helped out with seeding in the EAA target area, henceforth referred to as the target area.

2004 turned out to be a good year for seeding in the target area, with 20 days of seeding. This compares with 22 days of seeding in 2003, and only 8 in 2002. May turned out to have a few convective events, none of which were seeded due either to storms occurring at night or the location of the storms over the city of San Antonio. The first seeding mission of the year took place on June 7th, when a surge of tropical moisture brought waves of showers and thunderstorms northward across the area. June ended up being a very wet month, so wet in fact, that a temporary suspension was put in place for the last few days of June due to excessive rainfall and numerous Flash Flood Warnings being issued. The remainder of the year saw some good activity with October 27th being the final day of seeding within the target area. A brief discussion on the meteorological perspective of the seeding events will be presented later in the report.

Once the season concluded, Archie Ruiz, who works for Active Influence performing radar evaluations for the Texas weather modification projects, completed the radar evaluation of the program. Once again, it appears that seeding produced favorable increases in rainfall, with apparent lifetime extensions in the seeded clouds along with other positive results. These numbers are presented and discussed towards the end of the report.

As was mentioned in the 2003 annual report, the weather modification projects in Texas now have a contract with Weather Decision Technologies, Inc., based out of Norman, Oklahoma. The company provides the projects with live NEXRAD feeds from the various National Weather Service offices nearest to their respective target areas. For the target area, a feed from the WSR-88D radar at New Braunfels (KEWX) is used. The WSR-74C radar at the Pleasanton Municipal Airport is still used in conjunction with the NEXRAD data, and this secondary radar data may be analyzed in the near future to determine any possible differences.