September 2014 Climate and Hydrology Summary

Tulsa: September 2014 was the 52nd coldest (73.8°F, tied 1981, 1941; since 1905) and the 44th driest (2.19"; since 1888) September on record.

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

Fort Smith: September 2014 was the 64th warmest (74.5°F, tied 1973; since 1882) and the 13th wettest (6.90"; since 1882) September on record.

Fort Smith: No daily records were set or tied this month.

Fayetteville: September 2014 was the 30th coldest (68.9°F, tied 1997, 1991, 1964; since 1949) and the 23rd driest (3.58"; since 1949) September on record.

Fayetteville: Daily records set or tied this month include a record cold maximum temperature, a record cold mean temperature, and a record rainfall.

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

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for September 2014 ranged from 1” in portions of eastern Oklahoma to around 11” in Choctaw County. The majority of the eastern Oklahoma and northwest Arkansas received 2”-5” of rain this month. A large portion of the area only received 25%-75% of the normal September rainfall this month. However, above normal rainfall occurred across the northern portions of Osage, Washington, Nowata, and Craig Counties in northeast Oklahoma, as well as large portions of Sequoyah, Haskell, Le Flore, and Sebastian Counties. The eastern half of Choctaw County had 150% to near 300% of the normal September rainfall.

While most of eastern OK and northwest AR had another month with below normal rainfall, a few locations received an abundant amount of rain during September 2014.

No mainstream river flooding occurred in September 2014.

According to the Drought Monitor from September 30, 2014, Severe Drought (D2) conditions were occurring across portions of eastern Kay, Osage, Pawnee, Creek, western Tulsa, southern Washington, Counties in eastern Oklahoma. Moderate Drought (D1) conditions were present across portions of Osage, Washington, Nowata, Craig, Rogers, Tulsa, Okfuskee, Okmulgee, Mayes, Adair, and Sequoyah Counties in eastern Oklahoma, and Crawford, Madison, and Washington Counties in northwest Arkansas. Abnormally Dry (D0), but not experiencing drought, conditions existed across the remainder of eastern Oklahoma and northwest Arkansas, except for much of Haskell, Latimer, Le Flore, Pushmataha and Choctaw Counties in southeast Oklahoma and Sebastian and Franklin Counties in west central Arkansas.

According to the Oklahoma Climatological Survey, September 2014 was the 42nd driest for northeast Oklahoma, the 39th driest for east central Oklahoma, and the 35th wettest for southeast Oklahoma. Records go back to 1921.

It was a wet start to September, especially along the Kansas-Oklahoma state line. During the early morning hours of the 1st, a mesoscale convective system (MCS) moved across Kansas and Missouri, clipping far northeast Oklahoma and far northwest Arkansas. These storms brought around 0.25” to around 1” of rain. Showers and thunderstorms then developed again during the evening hours on the 1st in a very moist atmosphere across southeast Kansas near a stationary front. These storms moved south into far northeast Oklahoma, as another band of thunderstorms redeveloped near the front in southern/southeastern Kansas. This second round of storms drifted south and brought additional heavy rain to northeast Oklahoma due to their slow movement and training during the late evening and into the overnight hours. By morning on the 2nd, the storms began to move to the southeast across the remainder of eastern Oklahoma and northwest Arkansas. All but far southeast Oklahoma was affected by this complex of storms, which finally dissipated during the early afternoon. The heaviest rainfall occurred across the northern portions of Osage, Washington, Nowata, and Craig Counties, where 3”-6” of rain fell. Several rivers near the Kansas-Oklahoma border saw sharp rises, with the Verdigris River near Lenapah climbing 18.3’ in only 11.5 hours. The river crested at 21.5’, which is below the 30’ flood stage. Damaging straight-line winds also impacted Bartlesville, causing damage to the hospital, many residences, and the mid-high school. Rainfall totals >3” for 9/02/2014: Childers 2SSE, OK 5.41” Lenapah 3E, OK 5.39” Bartlesville 1NE, OK 4.67” Bartlesville 2W, OK 4.26” Vinita 10NNW, OK 3.84” Foraker 8ESE, OK 3.63” Copan Dam, OK 3.47” Copan 3ENE, OK 3.35” Quapaw, OK 3.11” Tahlequah, OK 3.08” Commerce, OK 3.00”

A cold front stalled across north Texas on the 11th, with warm advection occurring north of the front. This led to showers with isolated thunderstorms starting around midnight on the 12th and continuing for much of the day. Southeast Choctaw County received over 6” of rain, with much of eastern Choctaw County getting 6”-8” of rain from the 10th-12th. The cloudy, rainy day, combined with a secondary surge of colder air, led to chilly temperatures on the 12th. In fact, record low maximum temperatures were set across northeast Oklahoma and northwest Arkansas on the 12th.

Water Year 2014 (October 1, 2013 - September 30, 2014)

Tulsa: Water Year 2014 was the 9th coldest (58.8°F, tied WY1979, tied 1975; since 1906-07) and the 12th driest (27.92"; since 1893-94) Water Year on record.

Fort Smith: Water Year 2014 was the 31st coldest (60.4°F; since 1882-83) and the 65th wettest (41.02"; since 1882-83) Water Year on record.

Fayetteville: Water Year 2014 was the RECORD coldest (54.9°F; since 1949-50) and the 13th driest (38.59"; since 1949-50) Water Year on record. The previous coldest water year was 55.6°F in Water Year 1979.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for Water Year 2014 ranged from around 25” in Pawnee County in northeast Oklahoma to around 60” in Le Flore County in southeast Oklahoma. The majority of the area received 25”-40” of rain during the water year, with a large portion of southeast Oklahoma and west central Arkansas getting 40”-50”. The entire area, except for the far southeast corner of Le Flore County, received below normal rainfall for Water Year 2014. Most of eastern Oklahoma and northwest Arkansas saw only 50%-90% of the normal water year rainfall.

According to the Oklahoma Climatological Survey, Water Year 2014 was the 13th driest for northeast Oklahoma, the 18th driest for east central Oklahoma, and the 42nd driest for southeast Oklahoma. Records go back to 1921.

Outlook

The Climate Prediction Center CPC outlook for October 2014 (issued September 30, 2014) indicates a slightly enhanced chance for above median precipitation for far northeast Oklahoma and northwest Arkansas and equal chances for above, near, and below median precipitation for the remainder of eastern Oklahoma. This outlook also indicates equal chances for above, near, and below normal temperatures across all of eastern Oklahoma and northwest Arkansas. This outlook is based on short-range forecasts of expected weather conditions, primarily for the first half of October, as well as some medium range guidance.

The Climate Prediction Center CPC outlook for the 3-month period October-November-December 2014, CPC is forecasting a slightly enhanced chance for above median precipitation for all of the area except the far northeast corner of Oklahoma and far northwest corner of Arkansas. This outlook also indicates equal chances for above, near, and below normal temperatures across all of eastern Oklahoma and northwest Arkansas (outlook issued September 18, 2014). This outlook is based on both statistical and dynamical forecast tools and considering El Niño conditions.

According to CPC, current atmospheric and oceanic observations continue to indicate ENSO neutral conditions. Forecasts still indicated a weak El Niño event will occur, peaking in late autumn or early winter.