July 2015 Climate and Hydrology Summary

July 2015

Tulsa: July 2015 was the 35th warmest (84.2°F; since 1905) and the 13th wettest (6.72"; since 1888) July on record.

Fort Smith: July 2015 was the 21st warmest (84.5°F; since 1882) and the 6th wettest (8.79"; since 1882) July on record.

Fort Smith: Daily records set or tied this month include a record daily rainfall.

Fayetteville: July 2015 was the 30th warmest (78.6°F; since 1950) and the 4th wettest (8.05"; since 1950) July on record.

Muskogee had it's wettest July on record, with 13.58" of rain falling in July 2015. The previous record was 10.30" in July 1961.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for July 2015 ranged from around 1.5” in southeast OK to around 17” across east central OK. A large portion of eastern OK and northwest AR received 5”-8” of rain again this month. A large area of east central OK, including Okmulgee, McIntosh, Wagoner, Cherokee, and Adair Counties, as well as portions of eastern Creek, southern Tulsa, southeastern Mayes, Delaware, and western Washington (AR) Counties, had 10”-17” of rain in July 2015. This corresponds to at or above average rainfall generally along and north of I-40, and below normal rainfall south of I-40. The area between Interstates 44 and 40, which had the highest rainfall totals, ended the month with 3 to 6 times of the normal July rain, while Le Flore, Latimer, Pushmataha, Choctaw and southern Sebastian Counties only received 25%-90% of the normal rainfall this month.

There were 10 mainstem river floods at 7 river forecast points in July 2015. All of these floods were in the minor flood category.

Several rounds of heavy rain affected eastern Oklahoma and northwest Arkansas during July 2015, with the area between I-44 and I-40 receiving well above average rainfall this month. On the other hand, southeast OK ended the month with below normal July rain.

According to the Drought Monitor from July 28, 2015, drought free conditions continued across eastern Oklahoma and northwest Arkansas.

According to the Oklahoma Climatological Survey, the 30-day period July 2-31, 2015 was the 9th wettest for northeast Oklahoma, the 2nd wettest for east central Oklahoma, and the 39th driest for southeast Oklahoma. Records go back to 1921. For the 60-day period Jun 2-July 31, 2015, northeast Oklahoma ranked as the 15th wettest, east central Oklahoma was the 2nd wettest, and southeast Oklahoma was the 31st driest period. For the Water Year-to-date, October 1, 2014-July 31, 2015, northeast Oklahoma ranked as the 13th wettest, east central Oklahoma was the record wettest, and southeast Oklahoma was the 9th wettest period.

Outlook

The Climate Prediction Center CPC outlook for August 2015 (issued July 31, 2015) indicates a slightly enhanced chance for below normal temperatures across northeast OK and equal chances for above, near, or below normal temperatures elsewhere. The outlook also calls for a slightly enhanced chance for above median rainfall north of I-40 in northeast OK and northwest AR, and an equal chance of above, near, or below normal rainfall south of I-40. This outlook is based largely on dynamical models.

The Climate Prediction Center CPC outlook for the 3-month period August-September-October 2015, CPC is forecasting an enhanced chance for below normal temperatures and above median precipitation across all of eastern OK and northwest AR (outlook issued July 16, 2015). This outlook is based primarily on both statistical and dynamical forecast tools, but does consider El Niño conditions and possible impacts.

According to CPC, El Niño conditions are currently of moderate strength. The oceanic and atmospheric conditions indicate a strong ocean-atmosphere coping associated with El Niño. There is a 90% chance for El Niño to continue through the upcoming winter and an 80% for it to persist into early spring 2016. Forecasting tools indicate El Niño will peak with strong conditions during the late fall or early winter. However, El Niño impacts are generally most significant in the Southern Plains during the cold seasons.