August 2013 Climate and Hydrology Summary

August 2013 & Summer 2013

Tulsa: August 2013 was the 36th coldest (80.8°F, tied 2008, 1941, 1910; since 1905) and the 63rd wettest (2.88"; since 1888) August on record.

Fort Smith: August 2013 was the 52nd warmest (82.2°F, tied 1901; since 1882) and the 37th wettest (3.84"; since 1882) August on record.

Fort Smith: Daily records set or tied this month include a record cold maximum temperature.

Fayetteville: August 2013 was the 24th coldest (76.0°F; since 1949) and the 29th driest (2.82"; since 1949) August on record.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for August 2013 ranged from 0.25” in Choctaw County to over 10” in far northeast OK and northwest AR. A large portion of the HSA received 2”-6”. Locations north of a Vinita, OK to Fayetteville, AR line, plus most of Franklin, Madison, southern Creek, Okfuskee, Okmulgee, McIntosh, Haskell, northern Le Flore, and Muskogee Counties ended the month well above normal, receiving 150% to over 300% of the normal August rainfall. The remainder of the area had near normal rainfall up to 50% below normal rainfall, with the exception of Pushmataha and Choctaw Counties, which only received 5%-50% of the normal rainfall for the month.

The first half of August 2013 brought cooler temperatures and flooding rains. The second half of the month was hot and dry.

The Neosho River near Commerce experienced moderate flooding this month, with minor flooding occurring along the Verdigris River near Lenapah, the Illinois River near Watts and Tahlequah, and the Arkansas River near Muskogee.

Several Mesoscale Convective Systems (MCS) affected northeast Oklahoma and northwest Arkansas (as well as portions of Kansas and Missouri) during the first 7 days of the month, resulting in widespread 2" to over 10" of rain near the OK/KS and OK/AR/MO state lines. This lead to damaging flash flooding, as well as river flooding. Many roads and bridges were washed out in the hardest hit areas, but thankfully there was no loss of life.

According to the Drought Monitor from August 27, 2013, Severe (D2) drought crept back into the southwest portion of Choctaw County in southeast OK. Moderate (D1) Drought expanded into Choctaw and Pushmataha Counties in southeast OK. Portions Mayes, eastern Wagoner, Cherokee, Adair, southwest Delaware, Pushmataha, and Choctaw Counties in northeast OK and Washington County in northwest AR were classified as Abnormally Dry (D0), but not experiencing drought conditions.

According to the Oklahoma Climatological Survey, August 1-30, 2013 was the 23rd wettest for northeast Oklahoma, the 28th wettest for east central Oklahoma, and the 19th driest for southeast Oklahoma. Records go back to 1921.

Summer (June, July, August) 2013

Tulsa: Summer 2013 was the 40th coldest (80.4°F, tied 1947; since 1905) and the 52nd driest (9.50"; since 1888) Summer on record.

Fort Smith: Summer 2013 was the 44th warmest (81.3°F, tied 2000, 1957; since 1882) and the 24th wettest (13.89", tied 1950; since 1882) Summer on record.

Fayetteville: Summer 2013 was the 20th coldest (75.4°F; since 1950) and the 9th driest (6.97"; since 1950) Summer on record.

Outlook

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

For the 3-month period September-October-November 2013, CPC is forecasting forecasting an enhanced chance for above median precipitation and an equal chance for above, near, and below normal temperatures across all of eastern OK and northwest AR (outlook issued August 15, 2013). This outlook is primarily based on dynamical computer model output, though also includes some input from recent trends, soil moisture conditions, statistical forecast tools, and long-term trends.

According to CPC, ENSO neutral conditions are expected to continue into Autumn 2013, and likely to continue into Winter 2013-14.