* Weather pattern threatens continued drought
* High heat, persistent drought spread in US South
By Carey Gillam
KANSAS CITY, Mo., Aug 25 (Reuters) - Triple-digit temperatures baking the southern U.S. were amplifying the effects of historic drought in the region, and forecasts offered little hope for relief anytime soon.
Despite scattered rainfall earlier this month, increasingly hot and dry weather over the last week mitigated the benefits of the recent rainfall across the southern Plains, according to a report issued Thursday by a consortium of state and federal climatologists dubbed the U.S. Drought Monitor.
"You look at some of these places in Oklahoma and Texas and they are now approaching or breaking the number of 100-degree days," said Brian Fuchs, climatologist at National Drought Mitigation Center, which is housed at the University of Nebraska.
"Not only are we dealing with dryness ... but the heat is taking the dryness and amplifying the problem," said Fuchs.
And Fuchs said chances were growing, now at 50 percent, that this autumn would see a La Nina weather anomaly. A cooling of the waters in the Equatorial Pacific Ocean, La Nina shifts the weather pattern and signals dryness the next spring from California through the U.S. Southeast.
The short-term forecast was harsh, with drought seen persisting from eastern Arizona across Texas and into Oklahoma, expanding into more of Louisiana and Mississippi and parts of Arkansas, said Fuchs.
Recent rains earlier this month did offer some brief relief to parts of the southern Plains, but the dryness quickly re-established its grip on the region amid high heat, according to the Drought Monitor report.
Drought Monitor map: droughtmonitor.unl.edu/
In Texas, levels of extreme and exceptional drought totaled 94.42 percent of the state, up from 92.78 percent a week ago, the Drought Monitor reported.
Oklahoma saw the worst level of exceptional spread to 66.87 percent of the state from 66.84 percent.
New Mexico's exceptional drought expanded to 42.88 percent of the state from 42.39 percent, and Louisiana saw extreme and exceptional levels of drought spread to 55.97 percent of the state from 55.96 percent.
The deadly drought and triple-digit temperatures have broken numerous records, left the southern Plains and Mississippi Valley struggling to meet demand for power and water, and caused billions of dollars in damage to crops and livestock.
Texas officials have pegged agricultural losses due to the historic drought at more than $5 billion, making it the most destructive drought in the history of the Lone Star State.
The 12 months that ended July 31 were the driest in Texas history, and 2011 is on the verge of becoming the driest calendar year since records were first kept in the late 19th century, State Climatologist John Nielson-Gammon said. (Reporting by Carey Gillam; Editing by John Picinich)