February 2015 Climate and Hydrology Summary

Tulsa: February 2015 was the 12th coldest (36.0°F; since 1905), the 57th wettest (1.57", tied 1977; since 1888), and the 12th snowiest (5.8"; since 1900) February on record.

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

Fort Smith: February 2015 was the 14th coldest (37.6°F; since 1883), the 60th wettest (2.39"; since 1883), and the 17th snowiest (5.6"; since 1884) February on record.

Fort Smith: Daily records set or tied this month include a record cold maximum temperature, a record cold mean temperature, and a record daily snowfall.

Fayetteville: February 2015 was the 4th coldest (32.9°F; since 1950), the 27th driest (1.95"; since 1950), and the 14th snowiest (5.3"; since 1950) February on record.

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

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

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for February 2015 ranged from around 0.25” to around 2” from west to east across eastern OK and northwest AR. The majority of the area received 0.50”-1.5” of rain this month. The entire area received below normal rainfall this month. The greatest deficits occurred across Okfuskee, southern Okmulgee, McIntosh, and northern Pittsburg Counties, where only 10%-25% of the normal February rainfall was received. The remainder of the area received 25%-75% of the normal rainfall this month, except for portions of Benton, Delaware, and Ottawa Counties, which had slightly lower deficits.

No mainstream river flooding occurred this month.

The first two weeks of February 2015 were mostly mild and dry, with the second half of the month marked by several winter storms and cold temperatures.

Precipitation developed during the afternoon and evening hours of the 15th and expanded in coverage and intensity overnight and into the morning of the 16th as a vigorous upper-level wave approached the region. Initially, it was warm enough that the precipitation fell as rain, but as temperatures cooled, the rain transitioned to a mix of freezing rain and sleet. A transition to sleet, sleet and snow, and then all snow occurred during the nighttime and morning hours. Much of eastern OK and northwest AR saw snow on the 16th, with the highest totals of 3”-6” reported across northeast OK and northwest AR where frontogenetical forcing led to mesoscale banding of the snow and sleet. Thunder-sleet was observed, indicating rapid sleet accumulations. Many areas of northeast OK and northwest AR received 1”-2” of sleet (for reporting purposes, snow and sleet accumulations are combined). Reports of freezing rain indicated only a glaze to around 0.10” of ice accumulation occurred. Rain and snow liquid equivalent totals ranged from around 0.10” to near 1.5”, with the highest totals along the I-44 corridor, across northwest AR, and across far southeast OK.

A ridge of high pressure over the Gulf of Alaska continued to keep the door open for arctic waves to push southward across the Plains. A cold front ushered in more cold air on the 22nd, with light snow developing west of a Nowata to Muskogee line during the morning. Less than 1” of snow accumulation occurred. Additional precipitation developed further south across southeast OK and west central AR during the afternoon. While initially rain, a switch over to sleet and snow occurred as the colder air pushed south. Rain/liquid equivalent totals ranged from around 0.10” near I-40 to near 0.75” near the Red River. 1” to 3” of snow were reported across southeast OK and west central AR.
After a brief break in the precipitation, another round of snow and some sleet affected eastern OK and northwest AR along and south of a Pawnee to Bentonville line on the 23rd. The heaviest snowfall occurred across east central OK and northwest AR, where 1” to 4” was common. Rain/liquid equivalent totals ranged from a few hundredths to near 0.50”.
On the 25th, far southeast OK received some snow as a strong upper-level low pressure system moved across TX. Snowfall totals were generally 0.5” to 2”, with liquid equivalent of less than 0.10."

The last winter storm for the month affected the region on the 27th-28th as moderate to heavy bands of snow affected all of eastern OK and northwest AR. A narrow mesoscale very heavy snow band dumped 5”-7” of snow to the north and northwest of Tulsa during the afternoon and evening hours of the 27th, affecting much of Pawnee and Osage Counties. By the afternoon of the 28th, warm air advection caused the precipitation to slowly transition to a mix of snow, sleet, freezing rain, and rain across southeast OK. By the end of the event, 7”-8” of snow was reported in Barnsdall, Skiatook, and Hominy (Osage County) and 6” in Wister (Le Flore County). Most locations received 2”-4” of snow. Rain/liquid equivalent totals ranged from 0.10”-0.75”.

According to the Drought Monitor from March 3, 2015, Severe Drought (D2) conditions were occurring across portions of Osage, eastern Kay, Pawnee, northern Creek, and far western Tulsa Counties in eastern OK. Moderate Drought (D1) conditions were present across portions of Osage, Tulsa, Creek, Washington, Rogers, southwestern Nowata, and western Wagoner Counties in eastern OK. Abnormally Dry (D0), but not experiencing drought, conditions existed across the remainder of eastern OK and all of northwest AR.

According to the Oklahoma Climatological Survey, January 30-February 28, 2015 was the 32nd driest for northeast Oklahoma, the 29th driest for east central Oklahoma, and the 30th driest for southeast Oklahoma. Records go back to 1921. For the Water Year-to-date, October 1, 2014-February 28, 2015, northeast Oklahoma ranked as the 46th wettest, east central Oklahoma was the 47th wettest, and southeast Oklahoma was the 35th driest period.

Winter (December, January, February) 2014-15

Tulsa: Winter 2014-15 was the 43rd coldest (39.1°F, tied 1905-06, 2002-03; since 1905-06) and the 50th driest (4.29"; since 1888-89) Winter on record.

Fort Smith: Winter 2014-15 was the 41st coldest (40.4°F, tied 1995-96, 1944-45; since 1882-83), the 50th driest (6.92"; since 1882-83) Winter on record.

Fayetteville: Winter 2014-15 was the 17th coldest (36.3°F, tied 2002-03, 1987-88; since 1949-50) and the 12th driest (5.70"; since 1949-50) Winter on record.

According to the Oklahoma Climatological Survey, Winter 2014-15 was the 13th driest for northeast Oklahoma, the 31st driest for east central Oklahoma, and the 34th driest for southeast Oklahoma. Records go back to 1921.

Outlook

The Climate Prediction Center CPC outlook for March 2015 (issued February 28, 2015) indicates a slightly enhanced chance for above normal temperatures and an equal chance for above, near, and below median precipitation across all of eastern OK and northwest AR. This outlook is based on both short-term computer models for the first 2 weeks of March and medium range models for the last 2 weeks. The enhance chance for below normal temperatures is weighted toward the first week of March.

The Climate Prediction Center CPC outlook for the 3-month period March-April-May 2015 calls for a slightly enhanced chance for below normal temperatures across all of eastern OK and northwest AR, except for locations along the Kansas state line, where there is an equal chance for above, near, and below normal temperatures. This outlook also indicates equal chances for above, near, and below median precipitation across eastern OK and northwest AR (outlook issued February 19, 2015). This outlook is based on both statistical and dynamical forecast tools and considering weak El Niño conditions.

According to CPC, current atmospheric and oceanic observations are finally both displaying El Niño conditions, and an El Niño Advisory has been issued. CPC is forecasting a 50-60% chance that El Niño conditions will continue through summer 2015. Due to the expected weak strength, widespread or significant global impacts are not anticipated.