Thunderstorms developed across east central Oklahoma during the early morning hours of the 17th. A very moist air mass across the region and weak wind flow aloft resulted in slow-moving thunderstorms that produced very heavy rainfall.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS TSA wrote it up.
Thunderstorms developed across east central Oklahoma during the early morning hours of the 17th. A very moist air mass across the region and weak wind flow aloft resulted in slow-moving thunderstorms that produced very heavy rainfall. More than four inches of rain fell across western portions of Sequoyah County in just a few hours, which resulted in flash flooding.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Tulsa, OK wrote its last area forecast discussion before the first event at Aug 17, 5:33 AM CST, 3 hours 12 minutes earlier.
Area Forecast Discussion National Weather Service Tulsa OK 633 AM CDT Tue Aug 17 2021 .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Multiple thunderstorm clusters have develop across portions of eastern Oklahoma this morning. Looking at some of the latest HRRR guidance/radar trends, storms may stall before moving into northwest Arkansas with only light rain in the short term. Still appears KMLC/KFSM will likely see the highest chance for storms into the afternoon hours, but all TAF sites will again have the potential for brief IFR conditions as additional storms develop with diurnal heating. && .PREV DISCUSSION... /Issued 253 AM CDT Tue Aug 17 2021/ DISCUSSION... Scattered showers and storms will possible across eastern Oklahoma and western Arkansas today as an upper level trough persists across the area. While the bulk of the showers and storms will occur this afternoon, isolated to scattered showers and storms are possible this morning with isentropic lift producing activity across southeast Oklahoma and the upper level trough possibly kicking off some convection across northeast Oklahoma. Some of the storms could become strong with gusty winds and locally heavy rains possible. Temperatures today are expected to remain below normal with increased cloud cover across the region. The chances of showers and thunderstorms remains for Wednesday even as the upper level trough weakens. Another upper level shortwave in the southwesterly flow aloft will pick up the slack and provide the lift for the Wednesday activity. Once again, the strongest storms will be capable of gusty winds and locally heavy rains. The weather pattern remains unsettled Thursday into Friday as the southwesterly flow aloft persists across the region. A cold front will make a run at the area on Saturday as a mid-level shortwave moves out of the Rockies and across the northern Plains. However, it is looking more likely that the front will stall before making it into the area. However, the frontal boundary will be close enough to possibly produce scattered showers and storms across the northern portions of the area Friday night into Saturday. As we move into Sunday and into early next week, an upper level ridge builds across the region and puts a damper on the rain chances. This will also result in the return of above normal temperatures to the area. && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && AVIATION.....12
Hazardous Weather Outlook National Weather Service Tulsa OK 437 AM CDT Tue Aug 17 2021 ARZ001-002-010-011-019-020-029-OKZ049-053>076-180945- Adair OK-Benton AR-Carroll AR-Cherokee OK-Choctaw OK-Craig OK- Crawford AR-Creek OK-Delaware OK-Franklin AR-Haskell OK-Latimer OK- Le Flore OK-Madison AR-Mayes OK-McIntosh OK-Muskogee OK-Nowata OK- Okfuskee OK-Okmulgee OK-Osage OK-Ottawa OK-Pawnee OK-Pittsburg OK- Pushmataha OK-Rogers OK-Sebastian AR-Sequoyah OK-Tulsa OK-Wagoner OK- Washington OK-Washington AR- 437 AM CDT Tue Aug 17 2021 This Outlook is for Northwest and West Central Arkansas as well as much of Eastern Oklahoma. .DAY ONE...Today and Tonight. SEVERE THUNDERSTORM. RISK...Limited. AREA...Eastern Oklahoma and western Arkansas. ONSET...Ongoing. DISCUSSION... Scattered showers and thunderstorms are expected across eastern Oklahoma and western Arkansas into tonight as an upper level disturbance lingers over the area. Some of the storms could become briefly strong to marginally severe with gusty winds and heavy rains the main concern. SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT... Local Spotter Activation May Be Needed. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. WEDNESDAY THROUGH FRIDAY...Thunderstorm Potential. SATURDAY AND SUNDAY...Thunderstorm Potential...Dangerous Heat Potential. MONDAY...Dangerous Heat Potential. EXTENDED DISCUSSION... The potential for showers and thunderstorms will continue into Saturday as the weather pattern remains unsettled. Hot and humid conditions are set to return late in the weekend and into next week as an upper level ridge builds over the area. weather.gov/tulsa contains additional information.
The Western Arkansas radar (KSRX), 65 km away, was scanning. The volume nearest the first event began at 14:42 UTC.
2 flash flood. Local standard time, as filed.
Portions of several roads were reported flooded and closed, after locally heavy rain fell in the area.
Portions of the E 1020 Road, where it crosses Little Vian Creek, were flooded and impassable. Flood water washed away portions of the S 4550 Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oklahoma in 2021Every state in 2021This day in weather historyWarnings in Oklahoma, August 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 973224, 979375.