* U.S. Plains wheat at risk
* Drought continues in Plains States
* Midwest rains raise water levels of Mississippi River
By Sam Nelson
CHICAGO, Jan 11 (Reuters) - A cold snap expected early next week in the U.S. Plains' hard red winter wheat region may harm some of the crop that's already struggling amid the worst drought in more than 50 years, an agricultural meteorologist said on Friday.
"There will be a lack of snow cover in eastern Colorado and western Kansas, so there could be some damage there. Temperatures will fall to zero Sunday morning in western Kansas," said Andy Karst, meteorologist for World Weather Inc.
The U.S. Plains remained tightly gripped by a severe drought, according to a report issued Thursday, and fears mounted that another hot and dry year could lie ahead for key crop-growing and cattle-grazing regions.
The government declared much of the central and southern U.S. Wheat Belt a natural disaster area on Wednesday due to a persistent drought that imperils this year's winter wheat harvest.
In its first disaster declaration of the new year, the Agriculture Department made growers in large portions of four major wheat-growing states - Kansas, Colorado, Oklahoma and Texas - eligible for low-interest emergency loans.
The drought also trimmed U.S. corn and soybean production, leading to expectations for the government to again show tightening U.S. grain stocks in its January crop report to be released at 11:00 a.m. CST (1700 GMT) on Friday.
BRIGHTER OUTLOOK FOR RIVER SHIPPING
The drought had reduced water levels on the main U.S. water transportation route, the Mississippi River, to levels that mandated reduced barge loadings and had threatened to halt river traffic altogether.
Heavy rainfall this week in the U.S. Delta caused flooding and additional heavy rains are expected Saturday through Monday, according to Karst.
However, "the rains extended as far north as St. Louis and this helped bring up water levels on the Mississippi River," Karst said. "The rains and snow melt increased the water levels but this is temporary and the water levels will go back down in a week."
Shipping groups had warned as recently as last week of an effective closure of the river along that busy stretch, through which billions of dollars of grain, coal, fertilizer and other commodities flow every year.
"The forecasts are looking good," said Lt. Colin Fogarty, public affairs officer for the Coast Guard's upper Mississippi River sector that covers the Cairo area and northward.
Shippers are watching river gauges along the waterway to make sure they can transit low water areas.