May 2016 Climate and Hydrology Summary

Tulsa: May 2016 was the 39th coldest (67.9°F, tied 2015, 1972, 1923; since 1905) and the 45th driest (3.91", tied 1965, 1936; since 1888) May on record.

Tulsa: Daily records set or tied this month include record cold maximum temperatures.

Fort Smith: May 2016 was the 42nd coldest (68.3°F, tied 1966; since 1883) and the 48th driest (3.70", tied 1884; since 1883) May on record.

Fayetteville: May 2016 was the 6th coldest (62.1°F; since 1950) and the 32nd wettest (5.53"; since 1950) May on record.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for May 2016 ranged from around 2” to around 12”. A large portion of the area received 3”-6” of rain this month, with isolated areas receiving 10”-12”. This corresponds to 50%-110% of the normal May rain across most of eastern OK and northwest AR. Portions of Osage, Washington (OK and AR), Creek, Pushmataha, Cherokee, Adair, and Crawford Counties received 150%-200% of the normal May rain, while portions of Pawnee, Osage, McIntosh, Muskogee, Haskell, Latimer, and Le Flore Counties only ended up with 25%-50% of the normal May rain.

Severe thunderstorms developed and moved over portions of both northeast and southeast Oklahoma along and ahead of a dry line during the evening of May 9th. The strongest supercell storm moved across portions of Choctaw County in far southeast OK, producing 3 tornadoes, including an EF-3 near Boswell that was large, damaging, and injured 2 people. Heavy rain also occurred due to the two rounds of rainfall along and south of a McIntosh County to Crawford County line. Rainfall totals in this area generally ranged from 2”-6”, with lesser amounts of around 0.10” to 1” to the north. Information about this event can be found at https://arcg.is/1RNkyDs

A cold front moved into the area on the 11th. A line of scattered showers and thunderstorms developed across eastern OK and northwest AR, along and east of an Okmulgee to Miami line, during the early afternoon hours of the 11th. Thunderstorms then redeveloped over this same area during the late evening hours along and south of the front. Deep gulf moisture was in place, and combined with slow storm motions, heavy rainfall occurred. By midnight on the 12th, heavy rain was falling over the southern portions of Cherokee and Adair Counties, as well as portions of the surrounding counties. As storms increased in coverage across much of eastern OK and northwest AR, training storms continued to bring heavy rain to Cherokee and Adair Counties. Over 5”-7” of rain fell in about a 2.5 hour period, with a total of just over 8”, in this area by the time all of the storm activity had exited the region by mid-morning. The Cookson Mesonet site measured 8.31” in just a few hours, and flash flooding resulted in water rescues. Information about this event can be found at https://arcg.is/1RNkyDs

Severe thunderstorms developed near a dryline over central OK during the late evening hours of the 24th, and moved into eastern OK during the early morning of the 25th. A high-precipitation supercell developed over Noble County in north central OK on the afternoon of the 24th. This storm then moved southeast along a boundary, affecting portions of Pawnee and Payne Counties before moving across Creek County. This storm produced a rain-wrapped tornado northwest of Bristow, OK in Creek County during the evening. Another storm produced a short-lived tornado northeast of Morris, OK in Okmulgee County during the early morning hours of May 25. In addition to the tornadoes, heavy rain also occurred across the area from the evening of the 24th through the morning of the 25th. A slow moving severe thunderstorm produced prolific rainfall over Pushmataha County, with radar estimates of 5"-7" of rainfall in approximately 4 hours. 6.49" was measured 4 miles east northeast of Daisy, OK. Widespread 2"-4" of rain also affected northeast Oklahoma and far northwest Arkansas from the storms. This rain led to flash flooding as well as river flooding along the Polecat Creek near Sapulpa, the Deep Fork River near Beggs, the Caney River near Collinsville, and the Kiamichi River near Antlers.

According to the Drought Monitor from May 31, 2016, there were no drought conditions present in eastern OK and northwest AR. However, abnormally dry conditions were present across portions of Washington, Benton, Carroll, and Madison Counties in Arkansas.

According to the Oklahoma Climatological Survey, the last 30 days ending on May 31, 2016 was the 40th wettest for northeast Oklahoma, the 42nd driest for east central Oklahoma, and the 42nd driest for southeast Oklahoma. Records go back to 1921. For the Year-to-Date period Jan. 1-May 31, 2016, northeast Oklahoma ranked as the 44th driest, east central Oklahoma was the 41st driest, and southeast Oklahoma was the 26th wettest period. For the last 365 days (June 2, 2015-May 31, 2016), northeast Oklahoma was the 12th wettest, east central Oklahoma was the 2nd wettest, and southeast Oklahoma was the 5th wettest.

Spring (March-April-May) 2016

Tulsa: Spring 2016 was the 14th warmest (62.5°F, tied 1982; since 1905) and the 56th wettest (12.66"; since 1888) Spring on record.

Fort Smith: Spring 2016 was the 27th warmest (62.8°F; since 1883) and the 33rd wettest (15.06"; since 1883) Spring on record.

Fayetteville: Spring 2016 was the 29th warmest (57.1°F; since 1950) and the 33rd driest (13.19"; since 1950) Spring on record.

Outlook

The Climate Prediction Center (CPC) outlook for June 2016 (issued May 31, 2016), indicates an enhanced chance of above median precipitation across far southeast OK and equal chances for above, near, or below median across the remainder of eastern OK and northwest AR. This outlook also calls an enhanced chance of below normal temperatures across eastern OK and northwest AR. This outlook is based on both short- and extended-range weather forecasts and climate linkages to current soil moisture conditions. The Madden-Julian Oscillation (MJO) and waning El Niño did not play a major role in the June outlook.

For the 3-month period June-July-August 2016, CPC is forecasting a slightly enhanced chance for above normal temperatures across southeast OK and west central AR, and an equal chance for above, near, and below normal temperatures elsewhere. This outlook also calls for a slightly enhanced chance for above median rainfall over northeast OK and far northwest AR, with equal chances for above, near, or below median rainfall elsewhere (outlook issued May 19, 2016). This outlook is based primarily on both statistical and dynamical forecast tools, soil moisture conditions, and statistical guidance from current tropical and extratropical sea-surface temperatures.

According to CPC, a rapid transition from El Niño conditions to ENSO-neutral conditions is well underway. The latest forecast indicates a 50% probability of La Niña for June-August, increasing to 75% by autumn and winter. A La Niña Watch is in effect.