Drought Worries Grow For U.S. South, Midwest...05/24/00

CHICAGO, (Reuters) - Drought worries are growing in the Midwestern and Southern United States as summer heat approaches, meteorologists said on Tuesday.

"If conditions are dry at the end of May as we go into June, by the time we get to July, we're unlikely to get relief," said Kevin Trenberth, head of climate analysis at the National Centre for Atmospheric Research in Boulder, Colorado.

Dry weather promotes more dry weather, since there is little moisture to pick up from the ground to feed storms, Trenberth said. Summer heat will dry things out further.

Drought has hit hardest in the southwest, especially southern Texas and New Mexico; the central plains, primarily in western Nebraska and Iowa; and a swath along the Gulf of Mexico.

Less severe drought has gripped the nation's midsection, particularly Illinois and Indiana, and the Southeast, from Alabama through Florida up to Virginia.

The drought has inflicted damage on cotton crops in the South and grain crops in the Midwest, sapped needed moisture from the soil, and set the stage for wildfires in the tinder-dry forests of New Mexico and Minnesota and the parched grasslands of Florida.

"Rain is desperately needed," the Florida Agricultural Statistics Service said in a report this week. "Ponds, canals and water reservoirs are drying up."

The drought's grip loosened in Florida this week as scattered rains fell, while the upper Midwest has received nearly daily rainfall for almost two weeks.

A combination of meteorological factors appears to be at work in creating the drought. Most perplexing to meteorologists has been the on-again, off-again La Nina, a fickle phenomenon marked by cooler-than-normal surface waters in the eastern and central Pacific.

La Nina, along with its opposing, warmer-than-normal twin, El Nino, each have somewhat predictable effects on global weather patterns. La Nina has been known to divert storm tracks into Canada and away from the Midwest and South, exacerbating drought. El Nino frequently dumps rain on the West Coast, as happened in a brief flurry two weeks ago.

For now, La Nina has returned after a brief respite, though it appears to be waning after a two-year stay, meteorologists said. If it remains in force, storms may get pushed further North and will not draw moisture from the Gulf of Mexico to provide badly needed soaking rains.

Though the mid-Atlantic states suffered through a hot, dry summer last year, the last serious drought to afflict much of the United States was in 1988, and this year bears some resemblance. Long-term government forecasts have warned of a drought in parts of the nation.

Just this week, the National Oceanic and Atmospheric Administration (NOAA) reported its finding that the first four months of the year in the United States were the warmest in more than a century of record-keeping.

"We've been in a warm regime principally in the winter-spring season for several years," said Peter Leavitt, a private meteorologist. But Leavitt said the warmer average was largely due to temperatures failing to dip as low at night, not to scorching daytime temperatures.

"The doomsayers have been saying global warming would create more droughts, more fierce heat. Well, there hasn't been," Leavitt said.