Much of the country will continue to experience higher-than-normal temperatures this autumn, including the drought-stricken central United States, federal forecasters said yesterday.

The National Oceanic and Atmospheric Administration's latest three-month climate outlook calls for a toasty fall from the Southwest to the Northeast, with notable exceptions along the West Coast, Gulf Coast and Southeast.

Northern Alaska is also expected to be warmer than normal -- and wetter than normal -- through the beginning of December, forecasters said.

Meanwhile, a developing El Niño could bring above-average precipitation to the Gulf Coast and Southeast, NOAA's Climate Prediction Center said.

But the weather pattern -- signaled by unusually warm surface waters in the tropical Pacific Ocean -- is developing slowly. And that means this El Niño is likely to be weaker than scientists had first projected, said Huug van den Dool, a NOAA meteorologist.

"We believe there will be an El Niño, but the strength of it is debatable, and it may be a fairly weak one," he said.

Forecast models suggest it is "unlikely that a strong El Niño will develop," the Climate Prediction Center said yesterday in its new outlook.

Drought likely to persist through December

But even a weak El Niño, combined with dry soils in the central United States, will keep conditions warm in much of the country. And that means the drought that has gripped the Great Plains and upper Mississippi Valley since early summer is likely to persist through December, with "prospects for improvement" in the Ohio Valley, middle Mississippi Valley and southern Texas through the end of December, NOAA said.

The agency also says drought is likely to develop in the Pacific Northwest over the next few months.

The latest figures from the U.S. Drought Monitor, released yesterday, show drought expanded slightly last week to cover 64.82 percent of the contiguous United States, up from 64.16 percent the week before.

In the central United States, the area struck by "exceptional" drought, the most severe category, grew from 5.96 percent last week to 6.23 percent this week. The area of "extreme" drought, the second-worst category, expanded from 20.74 percent to 21.09 percent.

One measure of the current drought's strength can be seen in the path of slow-moving Hurricane Isaac, which dumped large amounts of rain as it traveled from the Gulf Coast through parts of the Midwest, said NOAA climatologist Jake Crouch.

Isaac could not erase water deficits

Drought has eased somewhat along Isaac's path through the Midwest and mid-South, but conditions there are still not back to normal.

"The water deficits were so severe that a large, slow-moving tropical system could not end the drought," Crouch said.

The hot, dry summer in much of the United States -- the third-warmest ever recorded in the lower 48 states -- has taken its toll on the country's agricultural output.

Corn production in the United States is predicted to be 4 billion bushels less than expected in May, and soybeans will be 600 million bushels less, said Pete Riley, an economist with the Agriculture Department's Farm Service Agency.

Grain stocks this year are insufficient compared with the aftermath of a similarly devastating drought in 1988, he said. The drought this summer, coupled with erratic rainfall in South America earlier this year, has left the international grain and oilseeds market particularly vulnerable to high prices.

"In 1988, we had huge stocks," Riley said. "The markets could easily handle that drought compared to today."