July 2013 Climate and Hydrology Summary

July 2013

Tulsa: July 2013 was the 28th coldest (81.2°F, tied 1975, 1973, 1928, 1926; since 1905) and the 26th wettest (4.93"; since 1888) July on record.

Fort Smith: July 2013 was the 62nd coldest (81.9°F, tied 1958, 1990; since 1882) and the 36th wettest (3.95"; since 1882) July on record.

Fayetteville: July 2013 was the 11th coldest (76.1°F, tied 1994, 1975; since 1950) and the 30th wettest (2.78"; since 1950) July on record.

Fayetteville: Daily records set or tied this month include record cold minimum temperatures.

McAlester: Daily records set or tied this month include record cold minimum temperatures and record cold mean temperatures.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for July 2013 ranged from 2” to 11”, with a large portion of eastern Oklahoma and northwest Arkansas receiving 3”-6”. However, a few locations in Crawford and Washington Counties in northwest Arkansas and Choctaw and Pushmataha Counties in southeast Oklahoma only received 1”-2” this month. Locations north of Hwy 412 in eastern Oklahoma, as well as Le Flore, Benton, and Carroll Counties ended the month well above normal, receiving 150% to 300% of the normal July rainfall. The remainder of the area had near normal rainfall, with the exception of Washington (AR), Crawford, Pushmataha, and Choctaw Counties, which only received 25%-75% of the normal rainfall for the month.

The first half of July 2013 was hot and dry, with the second half bringing periods of heavy rain and cooler temperatures.

The Tulsa International Airport recorded a 76 mph wind gust as a derecho moved across northeast Oklahoma, the highest known gust ever recorded at the site. Several Oklahoma mesonet sites recorded wind gusts in excess of 65mph in Osage and Tulsa Counties as well. Read more about this event at /tsa/weather-event_2013July23.

According to the Drought Monitor from July 30, 2013, only Washington and Madison Counties in northwest Arkansas were in Moderate (D1) Drought in eastern Oklahoma and northwest Arkansas. Portions of Mayes, Wagoner, Cherokee, Adair, Delaware, Sequoyah, Pushmataha, and Choctaw Counties in northeast Oklahoma and Benton, Carroll, Crawford, and Franklin Counties in northwest Arkansas were classified as abnormally dry (D0), but not experiencing drought conditions.

According to the Oklahoma Climatological Survey, July 2-31, 2013 was the 9th wettest for northeast Oklahoma, the 18th wettest for east central Oklahoma, and the 16th wettest for southeast Oklahoma. Records go back to 1921.

Outlook

The Climate Prediction Center CPC outlook for August 2013 (issued July 31, 2013) indicates equal chances for above, near, and below normal temperatures and precipitation across all of northeast Oklahoma and northwest Arkansas. This outlook is based primarily on dynamical computer models.

For the 3-month period August-September-October 2013, CPC is forecasting a slightly enhanced chance for above normal temperatures and an equal chance for above, near, and below median precipitation across all of eastern Oklahoma and northwest Arkansas (outlook issued July 18, 2013). This outlook is primarily based on recent trends, soil moisture conditions, and dynamic computer model output, with some input from statistical forecast tools and long-term trends.

According to CPC, ENSO neutral conditions remained through July. ENSO neutral conditions are expected to continue into Autumn 2013, followed by greater uncertainty in the ENSO state from late 2013 onwards.