February 2018 Climate and Hydrology Summary

Tulsa: February 2018 was the 54th warmest (42.0°F; since 1905) and the 5th wettest (4.82"; since 1888) February on record. A trace of snow fell, tying 17 other years (since 1900).

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

Fort Smith: February 2018 was the 40th warmest (45.7°F; since 1883) and the 6th wettest (7.03"; since 1883) February on record. A trace of snow fell, tying with 21 other years (since 1884).

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

Fayetteville: February 2018 was the 22nd warmest (42.3°F, tied 1974; since 1950) and the 3rd wettest (7.91"; since 1950) February on record. A trace of snow fell, tying 13 other years (since 1950).

Fayetteville: Records set or tied this month include a record warm minimum temperature, record warm mean temperatures, and a record daily rainfall.

McAlester: Daily records set or tied this month include record daily rainfall.

McAlester: February 2018 set a new monthly rainfall record for the month of February with 7.83". The previous record was 7.29" from February 2001.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for February 2018 ranged from around 1.5” in eastern Kay/northwest Osage Counties to around 12” in southeast OK. This corresponds to near normal to 25% below the normal February rainfall in eastern Kay and northwest Osage Counties, and 150% to around 400% of the normal February rainfall for the remainder of the area. There was a large rainfall gradient from northwest to southeast across eastern OK and northwest AR this month, primarily due to the heavy rainfall the last 2 weeks of February.

After an extended period of dryness, most of eastern Oklahoma and northwest Arkansas received heavy rain at the end of February 2018, with major flooding occurring along the Illinois River basin.

Heavy rain at the end of the month resulted in mainstem river flooding. Moderate to Major flooding occurred along the Illinois River, with Minor to Moderate flooding along the Spring River, Poteau River, lower Arkansas River, Lee Creek, and the Kiamichi River.

A band of post-frontal snow dropped southeast across southeast KS, far northeast OK, and southwest MO, bringing minor accumulation to far northeast OK. 0.3” was measured 5 miles west northwest of Vinita, OK, with estimates of a trace to around ¾” in locations that saw the snow. The liquid equivalent for this snow was less than 0.10”.

After a long stretch of little to no rain across the area, the upper-level pattern changed, bringing active weather to the region starting on the 16th. Several days of more significant rainfall occurred a few days later as a deep plume of moisture with sub-tropical origins surged north into the region on the 19th and remained over the area. Precipitable water values were nearly 1.5”, very high for this time of year. Showers and thunderstorms expanded across eastern OK and northwest AR on the 19th, bringing a few hundredths to around 1.5 inches of rain. Temperatures were very warm on the 19th, but that quickly came to an end as a strong cold front pushed south on the 20th. Temperatures dropped precipitously as the front moved through. Temperatures dropped over 20° in one hour, with a 20°-35° drop in temperature over a 3-hour period. Ahead of the front, widespread showers and thunderstorms developed in the warm, moist airmass on the 20th, and continued for much of the day and through the night. 2”-5” of rain fell across southeast through east central OK and northwest AR southeast of a McIntosh County to Delaware County line. This resulted in minor to moderate river flooding along the portions of the Illinois and Poteau Rivers. Elsewhere, rainfall totals were around 0.50” to near 2”. On the afternoon of the 21st, a 53-year old man drove across a flooded low water crossing three miles west of Stilwell and drowned. Temperatures continued to fall to below freezing behind the front, resulting in freezing rain/freezing drizzle across northeast OK and northwest AR starting on the afternoon of the 20th and continuing through the night. Ice accumulations ranged from a glaze to around 0.25”.

The active southwesterly flow continued, bringing additional periods of showers and thunderstorms from the 21st through the 25th. A shortwave lifted northeast across TX and into eastern OK on the 23rd, interacting with an area of warm air advection of the region. This resulted in widespread showers and thunderstorms over eastern OK and northwest AR during the day and again overnight into the 24th. By 6am CST on the 24th, most of eastern OK and northwest AR south of I-44 had received 0.75” to 2” of rain, with a heavier rain axis of 2” to around 4” of rain from McIntosh northeast into far northwest AR. The rain continued until the afternoon of the 24th, bringing an additional 0.50”-2” of rain to much of the area.

The 7-day rainfall total ending 2/26/18 ranged from 4” to around 10” from I-44 southeast. Most of area received 5”-8”, while locations northwest of I-44 had 1”-4”. The rain on the 23rd-24th, on top of wetted soils, resulted in both flash flooding and mainstem river flooding. Major flooding occurred along the Illinois River, with Minor to Moderate flooding along the Spring River, Poteau River, lower Arkansas River, Lee Creek, and Kiamichi River. Wister Lake (along the Poteau River in southeast OK) utilized up to around 88% of its flood control pool during the event.

With deep layer moisture overhead, widespread showers and thunderstorms again affected the area on the 27th, before tapering off from west to east during the evening hours. Rainfall totals ranged from 0.10” to around 2.5”, with the heaviest amounts of 1”-2.5” once again affecting southeast and east central OK. However, no additional flooding occurred. The final round of rain affected southeast OK through northwest AR on the 28th as a cold front moved through the region. Southeast OK through northwest AR received another 0.25” to near 3” of rain.

According to the Drought Monitor from from February 27, 2018, Severe (D2) Drought conditions were impacting northwest Osage County and eastern Kay County in eastern OK. Moderate (D1) drought conditions were present across portions of Osage, Washington, Nowata, Craig, Rogers, Pawnee, and Creek Counties in eastern OK. Abnormally Dry (D0) but not in drought conditions encompassed the remainder of eastern Oklahoma and northwest Arkansas, with the exception of Choctaw, Pushmataha, and southern Le Flore Counties where no dry conditions remain.

According to the Oklahoma Climatological Survey, the 30-day period January 31-March 1, 2018 was the 3rd wettest for northeast Oklahoma, the 2nd wettest for east central Oklahoma, and the Record wettest for southeast Oklahoma. Records go back to 1921. For the Year-to-Date period Jan. 1-March 1, 2018, northeast Oklahoma ranked as the 15th wettest, east central Oklahoma was the 4th wettest, and southeast Oklahoma was the 3rd wettest period.

Winter (Dec-Jan-Feb) 2017-18

Tulsa: Winter 2017-18 was the 46th warmest (40.3°F, tied 1986-87, 1942-43; since 1905-06) and the 36th wettest (6.51"; since 1888-89) Winter on record.

Fort Smith: Winter 2017-18 was the 58th warmest (42.1°F, tied 1982-83; since 1882-83) and the 17th wettest (11.54", tied 1927-28; since 1882-83) Winter on record.

Fayetteville: Winter 2017-18 was the 28th coldest (37.9°F, tied 2006-07, 1995-96, 1993-94; since 1949-50) and the 11th wettest (11.53"; since 1949-50) Winter on record.

Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for Winter 2017-18 ranged from around 1” in eastern Kay/far western Osage County to near 25” in southeast OK. This corresponds to around 40% to around 200% of the normal Winter rainfall from northwest to southeast across eastern OK and northwest AR. There was a significant rainfall gradient from northwest to southeast across eastern OK and northwest AR for Winter 2017-18, primarily due to the heavy rainfall at the end of February.

According to the Oklahoma Climatological Survey, Winter 2017-18 (December 1, 2017-March 1, 2018) was the 31st wettest in northeast Oklahoma, east central Oklahoma ranked as the 9th wettest, and southeast Oklahoma was the 2nd wettest period. Records go back to 1921.