* Price rises 4 pct to 77.86 cents, hits daily high limit
* Cotton above 80 cents could scare away millers -traders

By Barani Krishnan
NEW YORK, Oct 17 (Reuters) - U.S. cotton futures jumped
about 4 percent for a second straight session on Wednesday,
hitting a five-month high, on worries of a near-term supply
squeeze from delivery of poor quality fiber to the market.
Concerns that cotton from the early harvest of fields in the
southeastern United States had high levels of "micronaire", or
coarse fibers that could break during the spinning process at
textile mills, has sparked a rally since the week began.
The most-actively traded cotton contract on ICE Futures
U.S., December, rose the daily limit high of 3 cents a
pound to 77.86 cents. It was the highest level for a front-month
contract in U.S. cotton since May 15.
Traders said December cotton had potential to move up to
May's highs of above 80 cents a pound if the rally persisted,
cautioning that such high prices could scare away millers.
"This is the absolutely worst thing that can happen to
demand as mills will not chase price but use more synthetics in
their fiber mix," said Sharon Johnson, cotton specialist at
Knight Futures in Atlanta, Georgia.
Cumulatively, December cotton has gained 5.52 cents, or 7.6
percent, over the last two sessions. Cotton has outperformed
other commodities in U.S. trading, topping for a second day
winners on the Thomson Reuters-Jefferies CRB index
which tracks 19 raw materials markets.

Trading volumes have also been extraordinary.
Thomson Reuters data showed volumes in ICE cotton at above
21,844 lots by 1:10 pm EDT (1710 GMT), nearly 175 percent higher
than the 30-day average. On Tuesday, volumes crossed 54,000
lots, or 220 percent above the monthly norm.
Just last week, cotton prices appeared doomed after the U.S.
Department of Agriculture (USDA) issued one of its bleakest
reports on the crop in decades.
All that changed with the rising micronaire levels in cotton
delivered to the market.
Data showed that as of Oct 11, some 2.23 million running
bales of cotton had been ginned, or gone through the process
where fibers are separated from seeds.
Of these, just about 46 percent were considered tenderable,
guaranteeing a market for producers.
"The percent of cotton that can be delivered ... is much
lower than I have seen in many years," Johnson, of Knight
Futures, wrote in a market commentary. "It is 'high' mike (fiber
width) that is behind the quality issue."
If the market loses some of its momentum on Thursday,
concerns over the bearish USDA crop report could return, turning
sentiment.
The USDA report marked the third month in a row that the
agency had increased its estimates for worldwide stocks of
cotton since the new marketing season started on Aug. 1.
The latest revision put ending stocks 14 percent higher than
2011/12's 69.56 million bales.