A strong upper level low pressure system moved from the desert southwest into the Southern Plains in late December. Unseasonably moist air was in place across the region ahead of this approaching system as Pacific moisture in the mid and upper levels combined with very moist air in the low levels from the Gulf of Mexico. Strong atmospheric lift from the approaching upper level low and a warm front moving across the area, combined with this moisture, resulted in widespread locally heavy rainfall.
Eight to ten inches of rain fell across much of eastern Oklahoma. This excessive rainfall caused record flooding of the Illinois River near Watts and Tahlequah; major flooding of the Baron Fork near Eldon, the Flint Creek near Kansas, the Arkansas River near Muskogee, and the Poteau River near Poteau and Panama.

Flood in LE FLORE, OKLAHOMA
From 27-DEC-15 12:15:00 to 31-DEC-15 23:59:00 (CST-6)
Location: SHADY PT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Poteau River near Panama rose above its flood stage of 29 feet at 12:15 am CST on December 27th. The river crested at 44.97 feet at 12:15 am CST on the 29th, resulting in major flooding. Devastating flooding occurred with numerous county roads inundated by flood waters and extensive flooding of agricultural land. The river remained in flood through the end of the month, finally falling below flood stage at 11:00 pm CST on January 4th.

Flood in CHEROKEE, OKLAHOMA
From 27-DEC-15 06:15:00 to 28-DEC-15 09:45:00 (CST-6)
Location: ELDON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Baron Fork River near Eldon rose above its flood stage of 18 feet at 6:15 am CST on December 27th. The river crested at 25.44 feet at 9:30 pm CST on the 27th, resulting in major flooding. Campgrounds and cabins were severely flooded. The river fell below flood stage at 9:45 am on the 28th.

Flood in DELAWARE, OKLAHOMA
From 27-DEC-15 22:45:00 to 28-DEC-15 09:30:00 (CST-6)
Location: FLINT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Flint Creek near Kansas rose above its flood stage of 11 feet at 10:45 pm CST on December 27th. The river crested at 14.13 feet at 4:00 am CST on the 27th, resulting in moderate flooding. The river began to fall but after another round of heavy rainfall, the river crested a second time at 16.04 feet at 10:30 pm CST on the 27th, resulting in major flooding (3rd highest crest on record). Farmland and permanent campgrounds were flooded. The river fell below its flood stage at 9:30 am CST on the 28th.

Flood in MUSKOGEE, OKLAHOMA
From 27-DEC-15 09:00:00 to 31-DEC-15 23:00:00 (CST-6)
Location: CHASE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Arkansas River near Muskogee rose above its flood stage of 28 feet at 9:00 am CST on December 27th. The river crested at 35.41 feet at 5:45 pm CST on the 29th, resulting in major flooding. Agricultural land was inundated by flood waters and portions of the OG&E power plant grounds were flooded. The river fell below its flood stage at 11:00 pm CST on the 31st.

Flood in ADAIR, OKLAHOMA
From 27-DEC-15 00:15:00 to 29-DEC-15 10:30:00 (CST-6)
Location: WATTS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Illinois River near Watts rose above its flood stage of 13 feet at 12:15 am CST on December 27th. The river crested at 28.64 feet at 2:00 am CST on the 28th, resulting in record flooding. Disastrous flooding occurred from the Arkansas border to the Chewey Bridge, with many permanent campgrounds and cabins overtopped. Monetary damage estimates were not available. The river fell below flood stage at 10:30 am CST on the 29th.

Flood in CHEROKEE, OKLAHOMA
From 27-DEC-15 00:00:00 to 30-DEC-15 15:00:00 (CST-6)
Location: TAHLEQUAH
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Illinois River near Tahlequah rose above its flood stage of 11 feet at midnight CST on December 27th. The river crested at 30.69 feet at 1:00 pm CST on the 28th, resulting in record flooding. Devastating flooding occurred along the Illinois River from the Chewey Bridge to the headwaters of Lake Tenkiller. Highway 10 was closed northeast of its intersection with Highway 51, and many cabin parks were severely flooded. Monetary damage estimates were not available. The river fell below its flood stage at 3:00 pm CST on the 30th.

Flood in LE FLORE, OKLAHOMA
From 27-DEC-15 13:00:00 to 31-DEC-15 23:59:00 (CST-6)
Location: POTEAU KERR ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Poteau River near Poteau rose above its flood stage of 24 feet at 1:00 pm CST on December 27th. The river crested at 31.44 feet at 6:15 am CST on the 28th, resulting in major flooding. Extensive flooding of cropland occurred. Many county roads were inundated by flood water. The river remained in flood through the end of the month, finally falling below flood stage at 12:45 pm CST on January 3rd.