By Sam Nelson
CHICAGO (Reuters) - Tropical Storm Isaac, poised to hit Cuba on Saturday, will likely bring minimal relief from the worst U.S. drought in more than half a century, with rains expected in a limited area in the U.S. Southeast or possibly further west into Alabama and Mississippi, an agricultural meteorologist said on Friday.
"Computer maps have been all over the place but it looks like the storm will make landfall in Florida Sunday. That would bring the most rain, probably an inch to four inches or more in the southeast," said Andy Karst, meteorologist for World Weather Inc.
Karst said there are some weather guidance systems that peg the storm's path further west into the southern U.S. which could bring rain to the drought-stricken lower Midwest crop region.
"Confidence is low in that forecast; for now it looks like it will make landfall first in the Florida Panhandle," he said.
The southwest portion of the U.S. Midwest, including eastern Kansas, Oklahoma, Missouri and southern Iowa should receive from 0.50 inch to 1.00 inch or more of rain Saturday through Monday, with lighter showers in the balance of the Midwest, Karst said.
"It will provide minimal drought relief since it will turn warmer and drier again next week," he said.
Commodity Weather Group (CWG) on Friday said Isaac appeared most likely to track a bit further west, with landfall as a hurricane by Tuesday or Wednesday along the Gulf Coast, possibly Alabama or Mississippi.
Confidence was still low on the exact track of the storm, but the heaviest rains appear more likely to focus on Alabama, Mississippi and the Tennessee Valley rather than the Southeast based on Friday's forecast, CWG said.
Only minor delays in early corn harvest are expected, according to CWG.
Torrential rainfall and wind, while adding valuable soil moisture for fall wheat seeding, could harm some of the early- maturing corn and soybean crops that have already been weakened by the worst drought over the summer in half a century.
The annual Pro Farmer tour of Midwest crops found signs of severe crop losses in the top two corn- and soybean-producing states of Iowa and Illinois on Wednesday. Specialists on the tour pegged corn yields at the lowest in Illinois since 1995.
A Reuters poll of 11 analysts on Wednesday estimated the 2012 U.S. corn yield per acre at 121.5 bushels, the lowest in 16 years, and production at 10.5 billion bushels, an eight-year low.
In its first survey asking for estimates of the amount of corn to be harvested compared with plantings, the poll showed the percentage of harvested corn area at the lowest in nine years.
Analysts' expectations for corn production this season fell 3 percent below the U.S. government's forecast earlier in August and 6 percent below a similar poll of analysts' taken by Reuters at the end of July.
Soybean yield was pegged at 36.6 bushels per acre, an 8-year low, and production at 2.713 billion bushels, a 4-year low. Harvested soybean acreage was pegged at a near normal 97.5 percent of plantings.
The U.S. Department of Agriculture on Monday said 4 percent of the U.S. corn crop had already been harvested, the fastest start ever. The crop was planted early, then pushed to maturity by relentless heat and drought over the summer.
(Reporting by Sam Nelson; Editing by Bernadette Baum)