July 2011 Climate and Hydrology Summary

Unseasonably hot temperatures and dry conditions continued during the month of July across all of eastern Oklahoma and northwest Arkansas. Drought conditions worsened dramatically during the month due to the prolonged heat and lack of precipitation.

Tulsa: July 2011 was the 2nd warmest (90.9°F, since 1905) and tied for the 14th driest (0.36"; since 1888) July on record.

Tulsa: Daily records set or tied this month include a record warm max temperature on 7/10/11 and 7/27/11; record warm min temperatures on 7/11/11, 7/20/11 (tied), 7/24/11, 7/26/11 (tied), 7/27/11, and 7/31/11 (tied); and record warm mean temperatures on 7/10/11, 7/11/11, 7/24/11, 7/26/11 (tied), 7/27/11, and 7/31/11.

Tulsa: Tulsa reached or exceeded 100 degrees on 26 out of 31 days in July 2011, which ties for 2nd most 100 degree days in the month of July, falling 1 day short of the record of 27 days set in July 1936. Twenty-six 100 degree days were also seen in July 1980.

Fort Smith: July 2011 was the warmest (91.2°F) and the 7th driest (0.22") July since records began in 1883. July 2011 finished as the warmest month ever on record in Fort Smith.

Fort Smith: Daily records set or tied this month include record warm max temperatures on 7/5/11, 7/6/11, 7/7/11, 7/9/11 (tied), 7/10/11, 7/11/11, 7/12/11, 7/21/11, 7/22/11 (tied), 7/23/11, 7/24/11 (tied), and 7/27/11; record warm min temperatures on 7/7/11, 7/8/11, 7/10/11 (tied), 7/17/11, 7/22/11, 7/23/11, 7/24/11, 7/25/11 (tied), 7/28/11, and 7/31/11; and record warm mean temperatures on 7/6/11 (tied), 7/7/11, 7/8/11, 7/9/11, 7/10/11, 7/11/11, 7/12/11, 7/21/11, 7/22/11, 7/23/11, 7/24/11, 7/26/11 (tied), 7/27/11, 7/28/11, and 7/31/11.

Fort Smith: Fort Smith reached or exceeded 100 degrees on 30 out of 31 days in July 2011, which sets the record for the total number of 100 degree days in the month of July. Fort Smith ended July having reached or exceeded 100 degrees for 27 straight days, smashing the previous consecutive 100 degrees record of 17 that ended 7/26/1934.

McAlester: Daily records set or tied this month include a record warm max temperature on 7/4/11 and 7/9/11; record warm min temperatures on 7/17/11, 7/18/11 (tied), 7/21/11 (tied), 7/23/11, 7/27/11, and 7/28/11; and record warm mean temperatures on 7/7/11 (tied), 7/9/11, 7/10/11 (tied), 7/21/11 (tied), 7/23/11 (tied), 7/24/11, 7/27/11 (tied), and 7/28/11 (tied).

Fayetteville: Daily records set or tied this month include a record warm max temperature on 7/10/11, 7/24/11 (tied), 7/26/11, 7/27/11 (tied), and 7/28/11; and record warm min temperatures on 7/22/11 (tied), 7/23/11 (tied), 7/24/11 (tied), 7/25/11 (tied), and 7/28/11 (tied).

Rainfall totals for July 2011 ranged from less than 0.10” to isolated areas of 5”-6”. This was significantly less than the normal rainfall for July. Most of eastern Oklahoma and northwest Arkansas only received 10% to 50% of the normal July rainfall, though some areas received less than 5%. The NWS COOP observers near Bengal, Oklahoma and Okemah, Oklahoma only measured 0.10” and 0.05” for the month, respectively. The Oklahoma Mesonet sites in Wister and Sallisaw measured a meager 0.04” this month.

According to the Drought Monitor from July 26, 2011, extreme drought (D3) conditions expanded eastward across Pawnee, far southwestern Osage, Creek, Okfuskee, far western Tulsa, western Okmulgee, far western McIntosh, and western Pittsburg counties. Severe drought (D2) conditions encompassed the remainder of eastern Oklahoma, except Craig, Ottawa, and northeastern Delaware counties which are currently experiencing moderate drought (D1) conditions. Severe drought (D2) conditions also spread into parts of northwest Arkansas, including Sebastian, Crawford, far southwestern Washington, and far southwestern Franklin counties, with moderate drought (D1) conditions across the rest of northwest Arkansas.

According to the Oklahoma Climatological Survey (OCS) for July 2011, northeast Oklahoma ranked as the 19th driest, east central Oklahoma ranked as the 9th driest, and southeast Oklahoma ranked as the 6th driest July since records began in 1921. For the water year so far (October 1, 2010 - July 31, 2011), northeast Oklahoma ranked as the 9th driest, east central Oklahoma ranked as the 11th driest, and southeast Oklahoma ranked as the 7th driest water year on record.

Outlook

The Climate Prediction Center (CPC) outlook for August 2011 (issued July 31, 2011) indicates an enhanced chance for above normal temperatures across all of eastern Oklahoma and northwest Arkansas, an enhanced chance of below normal precipitation to the south of Interstate 40, and equal chances for above, near, or below average precipitation for areas north of Interstate 40.

For the 3-month period Aug-Sep-Oct 2011, CPC is forecasting an enhanced chance for above average temperatures and equal chances for above, near, and below median precipitation across eastern Oklahoma and northwest Arkansas (outlook issued July 21, 2011).

According to CPC, ENSO neutral conditions continued into early and mid July and are expected to continue into at least Fall 2011. Some recent computer model data are indicating that La Niña may redevelop during Fall 2011, but CPC indicates that ENSO neutral conditions are most likely to continue into early 2012.