Between May and June 2019, an extended sequence of heavy rainfall events over the South Central United States caused historic flooding along the Arkansas River and its tributaries.

Major and record river flooding occurred primarily in northeastern Oklahoma, and the elevated flows continued downstream into Arkansas where they caused additional inundation.

The prolonged combination of high atmospheric moisture and a sustained weather pattern extending across the continental United States led to frequent high-yield rainfall over the Arkansas River watershed.

Most rainfall occurred in connection with a series of repeated thunderstorms between May 19–21, which was then followed by additional rains that kept streams within flood stage.

The initial episode of torrential rainfall prompted the issuance of two flash flood emergencies for several counties in eastern Oklahoma on May 20, with numerous water rescues occurring during the event.

The prolonged release of reservoir water combined with surface runoff to cause near-record to record flooding along the Arkansas River.

Across the continental United States, 12 months preceding May 2019 were the wettest in 124 years of recordkeeping,[2] in line with a longer-term trend of increasing precipitation and heavy rainfall events due to climate change.

[4] This configuration was favorable for frequent rainfalls over the Southern Plains,[4] placing the jet stream in a position to draw the warm and moist air mass atop the Gulf of Mexico northward.

[5]: 23  Most of the rainfall associated with the flood event occurred during a 36-hour period between May 19–21 in a region spanning from northeastern Oklahoma to northwestern Arkansas.

[1]: 4  On May 22, the approach of an upper-level trough allowed moisture levels to quickly rebound in the wake of the previous day's storms.

A surge of warm air and strengthening low-level winds during the nighttime hours instigated additional storm formation over the same areas.

[5]: 30  The dominant trough over the western United States persisted, maintaining a southwesterly wind across the Southern Plains along which storms would travel.

[1]: 1  Within the warning region of the National Weather Service office in Tulsa, Oklahoma, at least one river was at flood stage between the evening of May 20 and the morning of June 13.

Another flash flood emergency was issued 30 minutes later for western Mayes, southeastern Osage, Rogers, northern Wagoner, and Tulsa counties.

[1]: 4  Atop saturated soils, the rainfall became surface runoff which flowed into streams and the United States Army Corps of Engineers's flood control pools.

[5]: 24  The submarine USS Batfish (SS-310) at the Muskogee War Memorial Park briefly took on water due to the swollen Arkansas River.

[17] The water levels in Kaw, Keystone, and Oologah lakes began to exceed their flood control limits after the May 22–23 rainfall.

[15] The Keystone Dam water release was its second largest on record and contributed to the Arkansas River reaching major flood stage in Tulsa during the afternoon of May 23.

[11] Widespread flooding occurred across numerous streams as the May 22–23 rains further exacerbated the elevated river stages from the earlier extreme rainfall event.

The entire stretch of the Arkansas River within the warning region of National Weather Service Tulsa—spanning 396 mi (637 km)–experienced a major flood.

Two unoccupied barges tethered together broke free from their moorings at the Port of Muskogee that evening, haphazardly floating downstream.

They were briefly obstructed by rocks before continuing downstream as the river rose, eventually colliding with the lock and dam system at Webbers Falls Lake and capsizing at around noon on May 23.

U.S. President Donald Trump approved a Major Disaster Declaration for Oklahoma on June 1 with an incident period from May 7–June 9.

[24] On May 22, officials from the Army Corps of Engineers warned of potentially record-breaking flood levels and flow rates in Arkansas, and urged people in floodplains and other flood-prone areas to relocate livestock and other belongings.

[15] Parks, homes, and businesses in Fort Smith were overtaken by the river, leaving parts of the city accessible only by boat.

[26] President Donald Trump approved a Major Disaster Declaration for Kansas on June 8 with an incident period from May 21–June 14.

[21] The United States Department of Housing and Urban Development disbursed $9 million in recovery fund grants to twelve Arkansas counties in December 2019.