La Nina Expected to Fade by Late April, U.S. Forecasters Say
The phenomenon, which also enhances hurricane formation in the Atlantic, weakened in February, the center said in a monthly report today. The impact of La Nina may linger through May because the atmosphere needs time to adjust.
“A majority of models predict neutral conditions to return during March-May 2012 and to continue through the Northern Hemisphere summer,” the center said.
La Nina has been blamed for drought that has hit Texas and Georgia particularly hard, according to the National Drought Mitigation Center at the University of Nebraska, Lincoln. Rain has eased drought conditions in eastern Texas, including Dallas, in recent months.
The weather pattern occurs on average every three to five years and usually lasts from nine to 12 months. It sometimes occurs in back-to-back years, as happened this year and last.
The current La Nina has parched crops in Argentina and Brazil and flooded plantations in Thailand and Malaysia. It also contributed to Australia’s wettest two-year period on record, the nation’s Bureau of Meteorology said Feb. 7.
The Pacific is expected to return to neutral conditions between La Nina and the warming phenomenon known as El Nino, in June, July and August, said the climate center, which is based in Camp Springs, Maryland.
La Nina cuts down on wind shear in the Atlantic, which can inhibit hurricane formation there, according to the National Oceanic and Atmospheric Administration.
Neutral conditions usually won’t inhibit hurricane growth. Only an El Nino, which increases wind shear across the Atlantic, has been shown to lower the number of hurricanes.
Last year’s Atlantic hurricane season spawned 19 storms with winds of at least 39 mph, tying it as the third-most active season in records that go back to 1851. Three other years, 2010, 1995 and 1887, also had 19 storms.
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