Watch this post for updates related to the severe weather outbreak.

Update: 3 p.m. 05/21: At 2:45 p.m. this afternoon, the National Weather Service doppler radar continues to detect showers and thunderstorms moving across eastern Oklahoma and northwest Arkansas, including Delaware County.

A line of stronger storms was approaching extreme southeast Oklahoma, with very heavy rainfall falling in parts of southeast Oklahoma, with approximately four inches in some areas.

Precipitation was moving towards the east at 30 mph.

Through 4:30 p.m. showers and thunderstorms will continue to spread eastward across the forecast area. The stronger storms will continue to produce very heavy rainfall, up to an inch per hour, along with strong damaging winds and hail.

Most affected areas will be south of I-40 and east of Highway 69.

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Update: 8 p.m. 05/20: The National Weather Service has issued a Hazardous Weather Outlook statement, for multiple counties in northeast Oklahoma including Craig, Delaware, Mayes and Ottawa.

This outlook outlook is for northwest and west central Arkansas as much of eastern Oklahoma.

Day one – Monday evening

Tornado – risk: critical
Area: eastern Oklahoma, west central and northwest Arkansas.
Onset – ongoing, with the area at greatest risk – northwest Arkansas. Severe Thunderstorms – risk: critical.
Area: eastern Oklahoma, west central and northwest Arkansas.
Onset – ongoing, with the area at greatest risk – southeast Oklahoma, west central and northwest Arkansas.
  Flash Flood – risk: elevated.
Area: locations north of I-40.
Onset – tonight.
  Heavy Rain – risk: significant.
Area: eastern Oklahoma and northwest Arkansas.
Onset – ongoing, with the area at greatest risk – locations north of I-40.

Short-term severe weather risks have shifted east, impacting northwest Arkansas and southeast Oklahoma. All modes of severe remain ongoing, even though some storms have begun a transition towards accelerating bow segments. A high risk of long track tornadoes, baseball size hail and wind gusts to 80 mph will continue.

Additionally, high moisture content will pose a heavy rain and flash flooding risk with storms that continue through the overnight period. The greatest threat tonight appears to be north of I-40. Two to four inches of rain in these areas may be common. Potential for localized seven inch amounts will quickly heighten the risk of life threatening flash flooding.

Spotter and emergency management action statement: Activation of the regional spotter network expected.

Days two through seven (Tuesday through Sunday)

Tuesday: Severe thunderstorm potential, heavy rain potential. Wednesday: No hazards. Thursday through Saturday: Thunderstorm potential. Sunday: No Hazards.

The severe weather risk Tuesday and Tuesday night is expected mainly across southeast Oklahoma and west central Arkansas and will again include the threat for flooding. After a brief break on Wednesday, low thunderstorm chances return Thursday through Saturday.

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Update: 7 p.m. - 05/20 - Robert Real, director of the Delaware County Emergency Management, reports that all the severe weather has passed through the Grove area at this time. 

There continues to be a tornado warning in Ottawa County, near Fairland, out of the immediate coverage area. There is also a tornado warning in the southern end of the county, near the Delaware/Adair county line, going into Siloam Springs, Ark.

Real said the Bernice sirens were activated when the storm, moving towards Fairland, went over the area. However the Grove sirens were not activated because the storm was out of the coverage area range.

He anticipates the storm will pass through DelCo within the next two hours.

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Update: 6:30 p.m. - 05/20 - The National Weather Service has issued a tornado warning until 7 p.m. for Ottawa County.

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Update: 6:17 p.m. - 05/20 - The National Weather Service has issued a severe thunderstorm warning remaining in effect until 7 p.m. for northeastern Rogers, Ottawa, southeastern Nowata, northern Mayes and northwestern Delaware and Craig Counties.

At 6:12 p.m. severe thunderstorms were located along a line extending from Cardin to Vinita to Bushyhead, moving east at 40 mph. These storms have a history of producing damaging winds to 66 mph in Centralia. Storm hazards include quarter sized hail, damaging wind gusts to 70 mph.

Miami, Afton, Ottawa, Fairland, Bernice State Park, Langley, Cherokee State Park, Disney Little Blue State Park, Disney, Ketchem, Cleora are in the path of this storm.

A Tornado Watch is in effect for the warned area. People outdoors should move inside a sturdy building. Stay away from windows and doors until the storm has passed.

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Update: 5:30 p.m. - 05/20 - Grove Police Chief Mark Morris recommends local residents continue to monitor television and other weather warning apps to be prepared for the upcoming severe weather.

"Be ready to take shelter in the event of a tornado warning," Morris said. 

He said residents should go over plans and know how to get to their safe areas in the event of we are under a tornado warning.

"Emergency management storm spotters have been activated and on the watch for severe weather and possible tornados," Morris said.

Delaware County Sheriff Harlan Moore said because the sheer size and strength of "this monster line" of storms, even if there is not a tornado warning, mobile homes may not withstand the winds.

Moore said people living in mobile homes should seek alternative shelter - preferably on the ground level.

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Update: 5:08 p.m. - 05/20 - The National Weather Service has issued a tornado watch until 10 p.m. CDT for northwest Oklahoma and northwest Arkansas, including, Delaware County.

A flash flood watch continues now thorough Tuesday evening for Delaware County.