GRAINS-Corn hits one-week high on U.S. weather worries

* Wet U.S. weather prompts pre-weekend short covering

* Soy rebounds after Thursday's sell-off; Brazil currency eyed

* Wheat higher rains hit Plains; U.S. dollar sags

(Recasts throughout; updates prices, adds quotes; changes byline, dateline, previous LONDON) CHICAGO, May 19 (Reuters) - U.S. corn futures rose about 1.5 percent on Friday and notched a one-week high as worries about lower temperatures and excessive rains in the Midwest prompted traders to cover short positions ahead of the weekend, analysts said. Soybeans firmed in a light rebound from Thursday's 3 percent sell-off as Brazil's currency stabilized. Wheat climbed on excessive moisture in U.S. winter wheat areas and a weaker dollar. Broad strength in commodities lent support, with the 19-market Thomson Reuters CoreCommodity CRB Index up 1.3 percent. As of 12:34 p.m CDT (1734 GMT), Chicago Board of Trade July corn was up 6-1/2 cents at $3.72-1/2 per bushel after reaching $3.73, its highest since May 11. CBOT July soybeans were up 9-1/2 cents at $9.54-1/4 a bushel and July wheat was up 9 cents at $4.34-3/4 a bushel. "Weather and the wetter forecast is back in focus. I think that means more to the trade going into the weekend," said Mike Zuzolo, president of Global Commodity Analytics. Corn in portions of the Midwest will need reseeding due to flooding and poor crop emergence, but farmers are running out of time. Corn planted after mid-May begins to lose yield potential. "Corn is firmer on the improved money flow and on concerns that rains in the southern Midwest will prevent re-planting in some areas," INTL FCStone chief commodities economist Arlan Suderman said in a note. Grains and soy were also recovering one day after Brazil's currency, the real, slumped as much as 8 percent, the biggest percentage drop since it was devalued in 1999. The currency fell following corruption allegations against the country's president, Michael Temer. The drop in the real sent CBOT soybeans tumbling on Thursday as Brazilian farmers rushed to sell soybeans which had been locked in storage bins. The country just completed the harvest of its largest-ever soy crop. Brazilian stocks and currency rebounded on Friday, slowing farmer offerings, Suderman said. CBOT July wheat touched a one-week high at $4.35-1/4 a bushel on fund short-covering and a weaker dollar, which tends to make U.S. grains more attractive on the world market. The U.S. dollar index was poised for its worst week in more than a year. Export sales of U.S. wheat in a weekly U.S. government report on Thursday topped trade expectations, and Egypt's main state grain buyer purchased U.S. wheat this week.

CBOT prices at 12:40 p.m. CDT (1740 GMT):

Last Net Pct Volume change change CBOT wheat Wc1 434.50 8.75 2.1 38492 CBOT corn Cc1 371.75 5.75 1.6 157762 CBOT soybeans Sc1 953.25 8.50 0.9 81403 CBOT soymeal SMc1 308.00 0.50 0.2 40964 CBOT soyoil BOc1 32.93 0.49 1.5 38288

NOTE: CBOT wheat, corn and soybeans shown in cents per bushel, soymeal in dollars per short ton and soyoil in cents per lb.

(Additional reporting by Nigel Hunt in London and Naveen Thukral in Singapore; editing by Ed Osmond and Jonathan Oatis)