* Traders monitor drought in exporter Brazil

* Strong demand in US supports CBOT soybeans

* Weekly US soy, corn export sales meet estimates

CHICAGO, Oct 19 (Reuters) - U.S. corn futures rallied above $5 a bushel to their highest level since August on Thursday, while soybean futures touched a four-week high.

The gains came as farmers are in the middle of harvesting their crops, a time when the influx of fresh supplies normally pressures prices.

A severe drought that is disrupting grain shipments and slowing soybean plantings in rival exporter Brazil helped to propel markets higher, analysts said. Gains in crude oil and weakness in the U.S. dollar also set a positive tone for grain futures, they said.

Still, forecasts for hefty U.S. corn supplies may limit further gains. When farmers have finished the harvests and all the grain has been delivered, the corn left in storage should exceed the amount that has sat in U.S. silos for seven years, according to the U.S. government.

"In the face of a 2 billion bushel-plus carryout, that's what makes me wonder how far we can really go," said Tomm Pfitzenmaier, analyst for Summit Commodity Brokerage in Iowa.

Most-active corn futures at the Chicago Board of Trade rose 13 cents to settle at $5.05 a bushel and touched their highest price since Aug. 21 at $5.05-1/2 a bushel.

Technical selling supported gains, traders said.

"Once you went above $5, it triggered a fair number of stops," Pfitzenmaier said.

CBOT soybeans ended up 4-1/2 cents at $13.15-1/2 a bushel after hitting its highest price since Sept. 21 at $13.17-3/4. A rally to July highs in soymeal futures helped support soybeans, traders said.

"Meal's been on a tear here," said Matt Wiegand, commodity broker for FuturesOne.

Weekly U.S. soybean export sales were 1.4 million metric tons for 2023-24, up 92% from the prior four-week average and within analysts' estimates. Corn export sales of 881,300 metric tons for 2023-24 were down 15% from the prior four-week average but also within analysts' estimates.

Difficult logistics in Brazil could create a short-term window of opportunity improved U.S. corn exports, a broker said. (Reporting by Tom Polansek in Chicago. Additional reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris; Editing by Subhranshu Sahu, Will DunhamD, Sherry Jacob-Phillips and Jonathan Oatis)