Harvey gained hurricane strength and is expected to become a major hurricane by the time it nears the Texas coast. Strong U.S. weekly export sales lent support.

Cotton futures settled strongly ahead Thursday, extending a string of higher closes to a rare six in a row as a major hurricane headed for the Texas coast.

December settled up 94 points to 69.83 cents, just off the high of its 133-point range from down 34 points at 68.55 to up 99 points at 69.88 cents. It posted a new high close since Aug. 9, the day before USDAΆs surprise crop and supply-demand reports when it had closed at 71.11 cents.

March gained 96 points to close at 69.22 cents, also just off the high of its 117-point range from 68.08 to 69.25 cents. October finished up 57 points at 70.17 cents.

Volume slipped to an estimated 17,341 lots from 25,446 lots the prior session when spreads accounted for 6,133 lots or 24%, EFS 750 lots and EFP 50 lots. Options volume dipped to 6,089 lots (4,185 calls and 1,904 puts) from 11,208 lots (6,036 calls and 5,172 puts).

Former Tropical Storm Harvey intensified into a hurricane Thursday and is expected to become a major hurricane by the time it nears the middle Texas coastline late Friday. Another round of U.S. weekly export sales topping expectations lent support.

Forecasters say more than 20 inches of rain could fall from Corpus Christi to Houston in the next seven days, with more than a foot falling in a large area to the Louisiana coast and up to 100 miles inland. Up to 10 inches or more could be recorded as far north in Texas as Austin.

A sizable portion of the high-yielding, high-quality South Texas cotton crop now is off the stalk, including seed cotton stored in modules in fields and on gin yards. The South Texas crop, though relatively small, is needed to begin replenishing depleted supply pipelines.

Gov. Greg Abbott has preemptively declared a state of disaster in 30 Texas counties. As of Sunday, the Texas cotton crop was 9% harvested and open bolls totaled 14%.

Concerns have been voiced about the potential impact of additional rains in the South Delta where producers have been hoping for an extended period of clear, warm weather following wet, cloudy conditions. Producers already had been scouting for target spot, bacterial blight and boll rot. No damage had been reported coming into the week, however.

The path of the storm after it makes landfall is uncertain, forecasters say, warning that it could dump several days of heavy rain in South Texas as it hangs over the state into next week. Depending on the eventual path, weather in the Texas High Plains also could be affected.

On the demand front, net U.S. all-cotton export sales for shipment this season came in at 284,500 running bales for the week ended Aug. 17, up from 190,400 RB the previous week.

This boosted 2017-18 commitments to 6.609 million RB, 48% of the USDA estimate and 2.456 million RB ahead of bookings a year ago. All-cotton shipments of 222,800 RB, up from 204,400 RB the week before, brought the total for the season to 546,500 RB, about 4% of the 2017-18 projection.

Net sales for next season of 50,800 RB raised the total for both crop years to a healthy 335,300 RB. Commitments for 2018-19 of 583,800 RB were 251,000 RB ahead of forward bookings a year ago.

Futures open interest grew 1,284 lots to 227,385 on Thursday, with DecemberΆs down 212 lots to 147,901 and MarchΆs up 1,487 lots to 55,729. Certified stocks declined 1,224 bales to 11,279.