June 2018 Climate and Hydrology Summary

Tulsa: June 2018 was the 14th warmest (81.8°F, tied 1936; since 1905) and the 26th driest (2.09", tied 1888; since 1888) June on record.

Tulsa: Daily records set or tied this month include record warm minimum temperatures and a record warm mean temperature.

Fort Smith: June 2018 was the 10th warmest (82.3°F; since 1882) and the 44th wettest (4.74"; since 1882) June on record.

Fort Smith: Daily records set or tied this month include a record warm minimum temperature, record warm mean temperatures, and a record daily rainfall.

Fayetteville: June 2018 was the 10th warmest (76.5°F; since 1950) and the 10th driest (2.08", tied 1971; since 1950) June on record.

Fayetteville: Daily records set or tied this month include a record warm mean temperature.

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

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for June 2018 ranged from around 1” to isolated amounts around 10” across eastern OK and northwest AR. The lowest rainfall totals were across northeast OK and northwest AR and Choctaw County in southeast OK. This corresponds to 10-75% of the normal June rainfall for most of northeast OK, northwest AR, and far southeast OK, and 110% to around 200% of the June normal for portions of east central OK into southeast OK, Pawnee County, and Osage County.

June 2018 was another hot month, with the monthly average temperatures 3°F-5°F above normal. Rainfall varied greatly across eastern OK and northwest AR this month.

A mesoscale convective system (MCS) moved south out of KS and into eastern OK and northwestern AR during the early morning hours of the 12th, dissipating by late morning as it reached southeast OK and west central AR. 60-70 mph winds associated with the leading edge of the complex occurred across portions of northeast OK and northwest, resulting in tree and power line damage. Rainfall totals were generally around 0.50” to around 1.5”, with isolated areas of 1.5”-4”.

Scattered showers and thunderstorms from southeast OK into northwest AR on the 20th as tropical moisture streamed into the region combined with an upper-level wave. Additional storm development occurred near I-44 during the afternoon along an outflow boundary (from earlier convection in KS). These storms propagated southeast through the evening hours. Rainfall totals ranged from 0.25” to around 3” along and south of I-44 and east of a Tulsa to Ada line.

An MCS moved into northeast OK during the late evening hours of the 22nd and moved quickly across eastern OK and western AR during the early morning hours of the 23rd. Some rain lingered into the mid-morning hours. Showers and thunderstorms then reignited late on the 23rd along a surface boundary that stretched from west central OK east southeast into southeast OK. A strengthening low level jet during the overnight hours sustained the convection over east central OK, leading to heavy rainfall. Meanwhile, another MCS moved southeast out of KS and into eastern OK, bringing damaging winds and rainfall to eastern OK and northwest AR through the mid-morning hours. A second MCS moved across northwest OK and into eastern OK during the afternoon of the 24th, again with damaging winds. These storms affected all but far northeast OK and far northwest AR through the afternoon and evening. The 24-hour rainfall ending at 7am CDT on the 24th was 0.50” to 6” across the affected areas of eastern OK and west central AR. Most of Okfuskee, McIntosh, and southern Okmulgee received 3”-6” of rain. The 24-hour rainfall ending at 7am CDT on the 25th was around 0.50” to around 3” across much of the region, with the exception of the area of northeast OK and northwest AR south of I-44 and north of I-40 where rainfall totals were only a few hundredths to around 0.50”. Over the 2-day period a large portion of eastern OK and western AR west and south of a Nowata to Tulsa to Fort Smith line received 1”-3” of rain, with 4”-7” across Okfuskee, southern Okmulgee, McIntosh, and northern Le Flore Counties.

According to the Drought Monitor from June 26, 2018, Severe (D2) Drought conditions were impacting western Osage, far northwest Pawnee, southern Pushmataha, and Choctaw Counties in eastern OK. Moderate (D1) drought conditions were present across portions of Osage, Pawnee, eastern Kay, Washington, Tulsa, Nowata, Craig, Ottawa, Rogers, Mayes, Delaware, Pushmataha, Choctaw, and Le Flore Counties in eastern OK, and Benton County in northwest Arkansas. Abnormally Dry (D0) but not in drought conditions encompassed portions of Pawnee, Creek, Tulsa, Mayes, Wagoner, Cherokee, Adair, Sequoyah, Haskell, Pittsburg, Latimer, Le Flore, Pushmataha, and Choctaw Counties in eastern Oklahoma and Carroll, Washington, Crawford, Madison, Franklin, and Sebastian County in west central Arkansas.

According to the Oklahoma Climatological Survey, June 2018 was the 34th driest for northeast Oklahoma, the 46th driest for east central Oklahoma, and the 48th wettest for southeast Oklahoma. Records go back to 1921. For the Year-to-Date period Jan. 1-June 30, 2018, northeast Oklahoma ranked as the 20th driest, east central Oklahoma was the 22nd wettest, and southeast Oklahoma was the 27th wettest period. For the last 365 days (July 1, 2017-June 30, 2018), northeast Oklahoma was the 37th driest, east central Oklahoma was the 38th wettest, and southeast Oklahoma was the 31st wettest.