August 2011 Climate and Hydrology Summary

Unseasonably hot temperatures continued during the month of August across all of eastern Oklahoma and northwest Arkansas, but most of the area, except for far southeast Oklahoma, saw near to above normal precipitation for the month. Despite increased precipitation, drought conditions persisted and even worsened some during the month, largely due to antecedent conditions and extreme heat.

Tulsa: August 2011 was the 5th warmest (87.6°F, since 1905) and tied for the 14th wettest (5.76"; since 1888) August on record.

Tulsa: Daily records set or tied this month include a record warm max temperature on 8/1/11 (tied), 8/2/11, 8/3/11, 8/5/11, 8/6/11 (tied), and 8/24/11; record warm min temperatures on 8/1/11 (tied), 8/2/11, 8/5/11, 8/23/11, and 8/24/11; and record warm mean temperatures on 8/1/11, 8/2/11, 8/3/11, 8/5/11, 8/24/11, and 8/31/11. The low temperature of 87°F on 8/2/11 also tied the all-time record warm min temperature that was previously set on 7/26/1980. The mean temperature of 100°F on 8/2/11 set the all-time record warm mean temperature.

Tulsa: Daily precipitation records set this month include a record rainfall amount on 8/10/11.

Tulsa: The low temperature of 87°F on 8/2/11 also tied the all-time record warm min temperature that was previously set on 7/26/1980. The mean temperature of 100°F on 8/2/11 set the all-time record warm mean temperature.

Tulsa: Tulsa saw its 2nd hottest meteorological summer on record. The average June through August temperature of 87.6°F fell just short of the record 88.0°F set in 1980.

Fort Smith: August 2011 was the 2nd warmest (88.2°F) and the 33rd wettest (4.13") August since records began in 1883.

Fort Smith: Daily records set or tied this month include record warm max temperatures on 8/1/11, 8/2/11, 8/3/11, 8/5/11, 8/6/11, 8/8/11, and 8/19/11; record warm min temperatures on 8/3/11, 8/4/11, 8/5/11, 8/6/11 (tied), 8/18/11, 8/23/11, 8/24/11 (tied), and 8/31/11 (tied); and record warm mean temperatures on 8/1/11, 8/2/11, 8/3/11, 8/4/11 (tied), 8/5/11, 8/6/11, and 8/31/11. The high temperature of 115°F on 8/3/11 set the all-time record warm max temperature. The mean temperature of 100°F on 8/3/11 set the all-time record warm mean temperature.

Fort Smith: The high temperature of 115°F on 8/3/11 set the all-time record warm max temperature. The mean temperature of 100°F on 8/3/11 set the all-time record warm mean temperature.

Fort Smith: Fort Smith ended its record streak of days reaching or exceeding 100 degrees, only warming to 98°F on 8/9/11. The now record number of 35 straight 100 degree days more than doubled the previous record of 17 that ended 7/26/1934.

Fort Smith: Fort Smith saw its hottest meteorological summer on record. The average temperature of 88.2°F for the June through August period crushed the previous record of 85.7°F set during the summer of 1936.

McAlester: Daily records set or tied this month include a record warm max temperature on 8/1/11, 8/2/11, 8/3/11, 8/4/11, 8/5/11, 8/19/11, 8/23/11 (tied), and 8/24/11; record warm min temperatures on 8/4/11, 8/5/11, 8/6/11, 8/7/11 (tied), 8/23/11, and 8/31/11; and record warm mean temperatures on 8/1/11, 8/2/11 (tied), 8/3/11, 8/4/11, 8/5/11, 8/6/11, 8/19/11 (tied), 8/23/11, 8/24/11, and 8/31/11. The mean temperature of 97°F on 8/3/11 and 8/5/11 set the all-time record warm mean temperature.

McAlester: The mean temperature of 97°F on 8/3/11 and 8/5/11 set the all-time record warm mean temperature.

McAlester: McAlester saw its hottest meteorological summer on record. The average temperature of 87.6°F for the June through August period beat the previous record of 86.2°F set during the summer of 1934.

Fayetteville: Daily records set or tied this month include a record warm max temperature on 8/1/11 (tied), 8/2/11, 8/3/11, 8/5/11, 8/6/11, and 8/8/11 (tied); and record warm min temperatures on 8/2/11, 8/3/11 (tied), 8/4/11, 8/5/11, 8/6/11, 8/19/11 (tied), 8/23/11, 8/24/11, and 8/31/11 (tied). The low temperature of 83°F on 8/5/11 set the all-time record warm min temperature.

Fayetteville: The low temperature of 83°F on 8/5/11 set the all-time record warm min temperature.

Fayetteville: Fayetteville saw its hottest meteorological summer on record. The average temperature of 81.9°F for the June through August period just beat the previous record of 81.4°F set during the summer of 1980.

Rainfall totals for August 2011 ranged from less than 0.25” to isolated areas of at least 10”. A large portion of eastern Oklahoma and northwest Arkansas received greater than normal precipitation during the month, with parts of southeast Oklahoma seeing significantly less than normal rainfall for August. Most of eastern Oklahoma and northwest Arkansas to the northeast of a Bristow to Clayton line received 100 to 200% of the normal August rainfall, though some areas received as little as 25 to 50% of normal in this region. Across the remainder of southeast Oklahoma, less than 25% of normal August rainfall was received, with some areas of Choctaw County seeing less than 5%.

According to the Drought Monitor from August 30, 2011, exceptional drought (D4) conditions expanded into eastern Oklahoma, encompassing most of Pawnee, Creek, Okfuskee, Choctaw, and far southwest Pushmataha counties. Extreme drought (D3) conditions were found across southern portions of Osage, western Tulsa, Okmulgee, western McIntosh, Pittsburg, Pushmataha, LeFlore, Latimer, western Sequoyah, western Cherokee, northeast Muskogee, and eastern Wagoner counties. Severe drought (D2) conditions stretched across northern and eastern parts of Osage, eastern Tulsa, Washington, eastern Okmulgee, eastern McIntosh, western and southern Muskogee, Haskell, eastern Sequoyah, eastern Cherokee, Adair, Ottawa, Mayes, Rogers, southwestern Nowata, and northeastern Craig counties. Moderate drought (D1) conditions were found across most of Nowata, Craig, and Delaware counties, as well as northeastern Rogers, northeastern Mayes, and northeastern Adair counties. Severe drought (D2) conditions also spread into parts of northwest Arkansas, including western Sebastian, western Crawford, far southwestern Washington, and Carroll counties, with moderate drought (D1) conditions across the rest of northwest Arkansas.

According to the Oklahoma Climatological Survey (OCS) for August 2011, northeast Oklahoma ranked as the 27th wettest, east central Oklahoma ranked as the 27th wettest, and southeast Oklahoma ranked as the 34th driest August since records began in 1921. For the water year so far (October 1, 2010 - August 31, 2011), northeast Oklahoma ranked as the 11th driest, east central Oklahoma ranked as the 12th driest, and southeast Oklahoma ranked as the 6th driest water year on record.

Outlook

The Climate Prediction Center (CPC) outlook for September 2011 (issued August 31, 2011) indicates an an equal chance for below, near, or above normal temperatures across all of eastern Oklahoma and northwest Arkansas and an equal chance of below, near, or above normal precipitation.

For the 3-month period Sep-Oct-Nov 2011, CPC is forecasting an enhanced chance for above average temperatures. The precipitation outlook includes an enhanced chance for below normal precipitation across most of eastern Oklahoma and west central Arkansas, with equal chances for above, near, and below median precipitation across far northeastern Oklahoma and most of northwest Arkansas (outlook issued August 18, 2011).

According to CPC, ENSO neutral conditions continued into August and are expected to continue into Fall 2011. Negative sea surface temperature anomalies are beginning to develop in the eastern Pacific, making a continuation of ENSO neutral conditions or the development of La Niña conditions equally likely after Fall 2011.