Thunderstorms increased in coverage and intensity across eastern Oklahoma on the 27th, as an upper level disturbance moved slowly through the region. The storms moved slowly, and some moved over the same areas repeatedly, which resulted in locally heavy rainfall and localized flash flooding.
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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 increased in coverage and intensity across eastern Oklahoma on the 27th, as an upper level disturbance moved slowly through the region. The storms moved slowly, and some moved over the same areas repeatedly, which resulted in locally heavy rainfall and localized 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 May 27, 5:14 AM CST, 2 hours 46 minutes earlier.
Area Forecast Discussion National Weather Service Tulsa OK 614 AM CDT Wed May 27 2020 .DISCUSSION... The 12Z TAF forecast discussion follows... && .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. For the most part, VFR conditions prevail across the area with enough mid cloud cover to prevent fog/low cloud from forming. However, there are periodic holes in the cloud deck, which have allowed pockets or areas of IFR/LIFR cigs/vsbys to develop here and there. Thus, have elected to do a morning TEMPO to cover at all sites which may be overkill, but this will prevent obs chasing. VFR conditions should return by midday, and the potential for storms thru the afternoon increases. Better and earlier chances are at the W AR sites where TEMPO groups were used, with slightly lower and later chances at the E OK sites where PROB30 groups were used. Storms should die off after 00Z. There is some suggestion of fog development by Thursday morning across portions of SE OK and NW AR. Will start off conservative with MVFR conditions toward the end of the forecast in those areas. Lacy && .PREV DISCUSSION... /Issued 355 AM CDT Wed May 27 2020/ DISCUSSION... Cut off upper level low continued to hold across the Southern Plains with the center positioned over Central/Eastern Oklahoma early this morning. The bulk of the ongoing precip was on the eastern side of the low with only a few isolated showers wrapping around the low across Eastern Oklahoma and Northwest Arkansas. Through this evening...the cut off low is expected to continue to slowly drift eastward with the low center over the eastern half of the CWA by tonight. In response...additional scattered rain showers and isolated to scattered thunderstorms are forecast for the CWA again as precip continues to wrap around the low. The greater precip potential looks to be across far Eastern Oklahoma into Northwest Arkansas into this evening before the eastern side of the low shifts east of the CWA. With the low directly over the CWA today and tonight...weak shear/flow and marginal instability should limit severe potentials today. However...if any updraft can sustain itself...500-mb temps of -13 to -16C...could aid in a couple pulse type strong storms this afternoon with hail/gusty winds. Organized severe potentials are not currently anticipated. Locally heavy rainfall could also be possible if caught underneath one of these storms. From the conditions mentioned above...afternoon temps look to only warm into the 70s again today. Tonight into Thursday...shower and isolated thunderstorm chances will remain possible for the CWA before the upper low finally begins to weaken Thursday evening. By Thursday night...an upper level trof axis dropping southeast through the Plains will help to push the weakening upper low out of the region with rain chances tapering off and finally exiting the CWA Thursday night. In the wake of the departing low...clearing skies and northerly flow will spread over the region as the upper trof axis moves through. With the return of the sun...temps Friday look to warm close to seasonal average. Extended model solutions continue to indicate a ridge of high pressure setting up over the Southern Plains during the weekend and holding over the region through much of next week. This will result in a more summer time pattern with temperatures warming back above seasonal average and drier conditions for the CWA. Highs by the latter part of next could maybe approach 90 degrees for parts of the CWA depending on the model of choice. && .PRELIMINARY POINT TEMPS/POPS... TUL 76 61 77 60 / 50 30 50 20 FSM 77 62 78 62 / 60 40 50 20 MLC 74 60 77 61 / 50 20 40 20 BVO 76 59 76 59 / 40 40 50 20 FYV 74 58 74 59 / 60 40 60 30 BYV 75 58 74 59 / 60 40 60 30 MKO 74 60 76 60 / 60 30 50 20 MIO 75 59 75 59 / 50 40 70 30 F10 74 59 76 60 / 50 20 50 20 HHW 76 60 79 62 / 50 40 40 20 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && AVIATION.....30
Hazardous Weather Outlook National Weather Service Tulsa OK 507 AM CDT Wed May 27 2020 ARZ001-002-010-011-019-020-029-OKZ049-053>076-281015- 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- 507 AM CDT Wed May 27 2020 This Outlook is for Northwest and West Central Arkansas as well as much of Eastern Oklahoma. .DAY ONE...Today and Tonight. HEAVY RAIN. RISK...Limited. AREA...Eastern Oklahoma and Northwest Arkansas. ONSET...Ongoing. THUNDERSTORMS WITH DANGEROUS LIGHTNING. RISK...Elevated. AREA...Eastern Oklahoma and Northwest Arkansas. ONSET...This Afternoon. DISCUSSION... Scattered rain showers and isolated thunderstorms this morning will continue to wrap around an upper level low pressure system slowly moving through the region. Additional scattered showers and thunderstorms will also be possible this afternoon across the region. A few of these afternoon storms could become strong with gusty winds...small hail and locally heavy rainfall being the main threats. Organized severe weather is not currently anticipated today. SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT... Spotter Activation Not Expected. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday. THURSDAY...Thunderstorm Potential. FRIDAY THROUGH TUESDAY...No Hazards. EXTENDED DISCUSSION... Rain showers and isolated thunderstorms will remain possible into Thursday night before the upper level low pressure system weakens and finally exits Friday. In the wake of the departing low pressure system...a ridge of high pressure is forecast to develop over the Southern Plains this weekend into much of next week. This will allow for dry conditions and temperatures warming back above seasonal average next week. weather.gov/tulsa contains additional information.
The Tulsa radar (KINX), 29 km away, was scanning. The volume nearest the first event began at 14:00 UTC.
5 flash flood. Local standard time, as filed.
Portions of several roads were flooded and closed in Wagoner.
Portions of several roads were flooded and closed between the Verdigris River and Fort Gibson Lake, south of Highway 51.
Portions of Highway 80 southwest of Hulbert were flooded and closed.
Portions of several roads were flooded in and around Hartshorne.
Portions of several roads were flooded in and around Chouteau, including Highway 69, which was closed. Several swift water rescues were conducted in the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oklahoma in 2020Every state in 2020This day in weather historyWarnings in Oklahoma, May 2020
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: 894880, 894881, 894890, 894892, 894895.