* Modest showers help stabilize crop declines
* But most corn already gone, soybean crop fading
* Corn prices nearing record high on Thursday
* Dry Delta a mounting worry for soy crop
* Hotly anticipated USDA crop report due Friday (Adds midday weather update, fresh meteorologist quotes, adds updates from weekly drought monitor)
By Sam Nelson
CHICAGO, Aug 9 (Reuters) - Midday weather updates on Thursday show no major let-up from the relentless drought in the U.S. Midwest that has slashed the corn crop and is now eating away at soybean production prospects, an agricultural meteorologist said.
"No significant shift from the pattern short term, there will be a few light showers but no soaking rains," said Kyle Tapley, meteorologist for MDA EarthSat Weather.
Tapley said light showers and cooler temperatures could be expected through the balance of this week which will provide minimal relief to crops that have been struggling against the yield-robbing impact of the worst drought in 56 years.
"The six to 10-day (next week) is for drier weather with highs in the 90s (degrees Fahrenheit/32-37 degrees Celsius) and drier and cooler weather could be expected in the 11-15 day forecast (into mid-August) in Missouri, Illinois, Indiana and Ohio," Tapley said.
Elsewhere in the Midwest, the outlook for two weeks out is for only minimal showers but cooler temperatures as the 2012 heat wave begins to wind down, Tapley and other meteorologists said.
"There will be some improvement, the cooler temperatures certainly will help. But most of the Midwest has not had enough rain for significant improvement," said Andy Karst, meteorologist for World Weather Inc.
"Crops may stabilize or decline a little more the next couple of weeks," he added.
Rainfall this week totaled 0.25 to 1.00 inch (0.6-2.5 cm) and was scattered over about half of the Midwest, but only about 25 percent received the heavier amount.
"There will be better rains today in the eastern Corn Belt, and the good news is that high temperatures the next couple of weeks will be in the 70s to 80s degrees Fahrenheit rather than 100 F," Karst said.
But "certainly no drought busting rains," he stressed.
Another round of modest showers were forecast for next week that will mimic the occasional downpours of the past couple of days, Karst said.
Commodity Weather Group (CWG) said the Midwest should be slightly wetter and cooler for the next two weeks, but soybeans in the U.S. Delta, a lush crop region near the lower Mississippi Valley, would be drier for the next 10 days.
That dryness would add stress to an already struggling soybean crop.
"Shower potential has become more limited in the next 10 days in the Delta. This will pose the greatest threat to double-crop soybeans in areas of Arkansas and bordering sections of Tennessee and Mississippi," said CWG meteorologist Joel Widenor.
Chicago Board of Trade corn futures soared to record highs on Thursday and the soybean market leaped over 3 percent as investors bought, bracing for government and private projections of sharp declines in domestic crop prospects.
USDA on Friday will release its August crop report and traders were getting prepared for another bull run in prices.
Domestic corn inventories could fall to a 17-year low next summer following this year's harvest, and soybean supplies could drop to their lowest in 32 years as drought continues to trim production prospects, according to a Reuters poll of grain analysts.
Soybean conditions began to stabilize last week on improved weather in a broad swath of the Midwest, while corn conditions declined again. Still, the ratings for both remained the worst since 1988.
In the past week, extreme drought doubled its grip on the top corn and soybean producing state of Iowa, according to a report by a consortium of climate experts issued Thursday.
The area under extreme drought in Iowa rose dramatically to 69.14 percent from 30.74 percent a week ago.
Drought expanded in other important farm states over the last week as well, to 94 percent of Missouri and more than 81 percent of Illinois for at least extreme drought.
"Every day we go without significant rain ... is tightening the noose," said Mark Svoboda, a climatologist with the University of Nebraska's National Drought Mitigation Center. (Additional reporting by Carey Gillam in Kansas City; Editing by Marguerita Choy)