Precipitation Enhancement Kicks Off 13th Year at PGCD

Panhandle Groundwater Conservation District (PGCD) will kick off its’ thirteenth year of precipitation enhancement this month as we move into the spring across the Texas Panhandle. This year has started off slightly better than the spring of 2011, with the La Niña in place not as strong as last year. La Niña was the primary reason for the severe drought that the Texas Panhandle experienced last year. According to the Climate Prediction Center, La Niña is expected to transition to more neutral conditions by the end of April and continue through the Northern Hemisphere summer of 2012.

Models that predict La Niña, which are when temperatures are cooler than normal across the eastern Pacific Ocean, and El Niño, which are when temperatures are warmer than normal across the eastern Pacific Ocean, are trending towards a neutral condition for the Summer. Neutral conditions would benefit the Panhandle by bringing more average rainfall chances for the summer. Where as when El Niño is in place we see increased rainfall chances in the Panhandle, and when La Niña is in place we see less rainfall chances which is what occurred during 2011.

However, because we often see a slow demise of a La Niña events, impacts are expected to persist into the upcoming season. One of those impacts includes increased chances of above-average temperatures across the south-central United States. Here in the Texas Panhandle we are already seeing this with records highs during March. Amarillo broke three record high temperatures in March which occurred on March 15, 16 and 25.

The 2011 Precipitation Enhancement season concluded on September 3. The season began on April 25; however, last year was a hard year in the Texas Panhandle since rainfall was very limited due to the extreme drought most of Texas experienced along with other states in the United States. Table 1 shows the number of days flown, seeding flights, reconnaissance flights and hours flown per month through the 2011 season. There were not a lot of favorable conditions for seeding until the neutral conditions allowed for some dynamics across the Texas Panhandle to provide some seeding opportunities in July and August.

Table 1 shows the number of days flown, seeding flights, reconnaissance flights, and hours flown per month through the 2011 season.

The rainfall amounts in 2011 were in most cases below anything the Texas Panhandle has ever seen. During 2009 and 2010, most counties were above the district normal of 16.43 inches, and there were significant increases in rainfall from 2009 to 2010. However, when comparing the 2011 rainfall to those years it is evident that this year’s rainfall was severely hindered by La Niña with most counties seeing less than five inches of rainfall from April through September. Table 2 shows the rainfall values for the District counties for 2009-2011 and their differences.

Table 2 shows the comparison of rainfall from 2009-2011 during April-September in PGCD.

Last year’s seeding season was still considered very successful, providing on average a 20 percent rainfall increase per county according to Active Influence and Scientific Management. This increase was calculated using real-time rain gauge measurement collected throughout the District, and by comparing the radar data of the seeded clouds to the non-seeded clouds. This increase calculated out to an average of 0.89 inches of additional rainfall per county within the PGCD target area. Active Influence and Scientific Management analyzed a total of 38 clouds in 24 operational days. The results were evaluated as excellent with timing of seeding at 93 percent and no seeding opportunities missed. The cost of the program per acre was calculated at $0.037.