Saturday, January 22, 2011

Drought to persist in southern US

NOAA: While wet and snowy weather has dominated the western U.S., persistent drought conditions are likely to linger in the Southern Plains and Southeast through mid to late spring, according to NOAA’s National Weather Service. La Niña has kept storms and most of their precipitation in the north, leaving the South drier than normal.

“The speed with which the drought developed across the southern United States is rather unusual considering that just last year El Niño dominated the region with abundant precipitation,” said Bill Proenza, director of NOAA’s National Weather Service southern region.“ Then it was as if a switch was flipped during the summer, changing to La Niña conditions.”

One of the major aspects of the emergence of La Niña was a very busy Atlantic hurricane season, which spawned 19 tropical storms, making it the third most active on record. Despite the large number of storms, only Hurricane Alex and Tropical Storm Hermine produced any appreciable rainfall in the southern United States. Those storms only affected Texas; no significant rainfall from an organized tropical system fell along the Gulf Coast from Louisiana to Florida.

Sparse tropical rainfall and the dry conditions associated with La Niña combined to create severe to extreme drought conditions for nearly a third of the South and Southeast by late fall and early winter.

While the drought touches all of the Gulf Coast states, Texas and Florida are the most affected. From October through December, Texas received only five to 50 percent of normal precipitation, with portions of the lower Rio Grande averaging less than five percent of normal. During that period, for example, Brownsville received only 0.14 inches (normal is 6.55 inches) and Del Rio received 0.04 inch (normal is 3.89 inches). To the north in Austin, only 1.55 inches of rainfall was observed, compared to the normal of 8.34 inches….

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