While producers in California and the Pacific Northwest struggled with too much precipitation on both ends of the growing season, their counterparts in the Southeastern and Mid-Atlantic regions dealt with a devastating dry spell from the middle of summer onward. In between, growers in a big chunk of the western Corn Belt and Upper Midwest found it difficult to find a string of four or five consecutive days for drying hay during most of the summer.

As 2011 unfolds, most weather observers are focusing on the effects of a weather phenomenon known as La Niña to see what lies ahead. A La Niña is characterized by lower-than-normal surface-water temperatures in the central Pacific Ocean at the equator.

Climatologists started to get an inkling that the shift from an El Niño pattern, which had dominated the weather during the previous year, to a La Niña was taking place in late July. By late August, the La Niña was firmly locked in place. Areas of the country that had been enjoying abundant moisture early in the growing season – the Mississippi and Ohio River valleys, many parts of Texas and a large chunk of the Southeast – experienced a transformation to much drier- and hotter-than-normal weather conditions.

The effects were dramatic for forage producers in many areas. With late-summer hay growth choked off, many growers reported that they were unable to get the cutting that had seemed such a sure thing earlier in the season. Livestock producers saw pastures dry up quickly, forcing many to begin feeding hay several months earlier than normal and/or cull their herds.

Purdue University forage specialist Keith Johnson reports that livestock producers in southeastern Indiana had already begun feeding hay in mid-September to supplement their pastures. Two months later, reports were coming in that some were also hauling water because stock ponds had dried up.

“When you start feeding hay in September and hauling water in November, it’s not a good thing,” says Johnson.

Determining how long a La Niña might last is always a challenge for weather forecasters, says Brian Fuchs, climatologist for the National Drought Mitigation Center at the University of Nebraska-Lincoln.

“A La Niña will typically peak around the first of January and then subside in early spring,” he explains. “But if we look at a dozen different forecast models, this one looks like it could come off more slowly. We could be into summer before it’s done.”

At the very least, Fuchs says, an area of the country stretching from eastern Arizona through New Mexico and Texas, along the Gulf Coast into Florida and up into Georgia and the Carolinas will likely have drier and warmer weather through the winter months.

On the other hand, if the La Niña remains true to form, relief could come relatively quickly to areas of the Ohio River Valley – Indiana, Ohio, Tennessee and Kentucky – that experienced drought this past fall.

“If this La Niña plays out like a La Niña typically does, the winter in those areas should be on the wet side,” says Fuchs. “We’ll probably see some improvement in soil moisture and pasture conditions as we get into spring.”

The La Niña was also influencing weather patterns along a line running northward from Arizona into southern Minnesota this past fall, notes Iowa State University Extension climatologist Elwynn Taylor.

“In the Upper Midwest, we were coming off a period where we had three of the wettest Octobers in consecutive years (2007, 2008 and 2009) ever,” he says. “But this past October, we were very dry.”

Taylor believes the current version of La Niña is acting exactly the same as one that dominated the national weather picture in the fall of 1973.

“In 1974, the Corn Belt had its worst drought since 1955,” he says.

As of late November, Taylor put one-in-three odds on La Niña staying in place well into the summer. This would increase the prospects for a Corn Belt drought in 2011 to around 35%.

“When people hear that, they think it’s only one in three. So it doesn’t sound too bad. But that’s really still pretty high,” he says.

Taylor also notes that the Corn Belt hasn’t experienced a major drought since 1988. That fact alone increases the probability that there will be a drought somewhere in the region during the coming growing season.

USDA meteorologist Brad Rippey agrees that a strong La Niña could increase the probability of a Midwestern drought this coming summer.

“But it’s by no means a certainty,” he says. “If it were to wane during the spring, as many people expect, it would likely have very little effect on the Midwestern summer.”

In the meantime, pasture and rangeland in the Southern Plains states – Texas, eastern Colorado, Kansas and Nebraska – will likely see, as the winter progresses, a continuation of the dry weather that began in the fall.

“It’s usually pretty dry during this time of year anyway,” says Rippey. “But with the fairly windy conditions and rapid temperature fluctuations that result from La Niña, pastures and winter wheat are going to be under stress.”

La Niña could also exert a cold and stormy influence this winter from Wisconsin and Minnesota into the Northern Plains states and all the way to the West Coast.

“A lot of snow and cold would be a double-edged sword,” says Rippey. “The moisture and snow cover would be good news for winter grains and pastures. But it would make for difficult rural travel and create problems for livestock producers in the Northern Plains and the feedlots in the interior regions of the Northwest.”

If that pattern persists well into spring, hay growers in the Pacific Northwest could be in for another unusually wet growing season.

“It would definitely be very lush and green in that part of the country,” says Rippey. “But we could also see another slow hay season. It’s pretty safe to say that, by spring of 2011, a lot of people in the Northwest would like to see La Niña end.”