Alert archive / Oklahoma / Flash Flood Warnings in 2021

Flash Flood Warning 60, NWS Tulsa, OK

August 17, 2021Sequoyah County, Oklahoma

NWS Tulsa, OK issued this flash flood warning at Aug 17, 2021, 9:39 AM CDT for Sequoyah County, Oklahoma. It was in force for 3 hr. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 17, 2021, 9:39 AM CDT (14:39 UTC)
Expired
Aug 17, 2021, 12:45 PM CDT
In force
3 hr
Issued by
NWS Tulsa, OK
Area
Storm-based polygon
Flood severity
None

County Sequoyah County, OK

The radar

The Western Arkansas radar (KSRX), 60 km from the middle of the area, began a volume at 14:42 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 17, 9:45 AM CDTFLASH FLOOD3 Nw Vian, OKSPOTTER REPORTS ROADS CLOSE TO BEING IMPASSABLE NORTH OF CARLISLE VERIFIED BY VIDEO. SEVERAL FIELDS ARE ALSO UNDERWATER IN NUMEROUS VIDEOS SENT IN BY THE SPOTTER. SOME OF THIS WATER IS SPILLING ONTO VARIOUS ROADWAYS.
Aug 17, 10:16 AM CDTFLASH FLOOD4 Ne Vian, OKSPOTTER HAS VIDEO OF WATER RUSHING OVER E 1020 ROAD WHERE LITTLE VIAN CREEK INTERSECTS IT. ROAD IS IMPASSABLE. ANOTHER COUNTY ROAD NEARBY OR S 4550 HAS SEEN HALF THE ROADWAY WASH AWAY.
Aug 17, 10:41 AM CDTHEAVY RAIN 4.51 N Sallisaw, OKEM REPORTS HE RECEIVED 4.5 INCHES OF RAINFALL. SEVERAL ROADS WERE ALSO FLOODED ACROSS THE COUNTY INCLUDING 12 INCHES OF WATER OVER HIGHWAY 17 NORTH OF SALLISAW.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Springfield, MO (KSGF), launched 12:00Z, 2.7 hours before the alert went out and 188 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Springfield, MO at 12:00Z on 2021-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 430 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Springfield, MO at 12:00Z on 2021-08-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 33 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
430 J/kg
Mixed-layer CIN
-58 J/kg
Mixed-layer LCL
1276 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
33 m²/s²
0-3 km storm-relative helicity
34 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

854 
WGUS54 KTSA 171439
FFWTSA
OKC135-171745-
/O.NEW.KTSA.FF.W.0060.210817T1439Z-210817T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tulsa OK
939 AM CDT Tue Aug 17 2021

The National Weather Service in Tulsa has issued a

* Flash Flood Warning for...
  Northwestern Sequoyah County in east central Oklahoma...

* Until 1245 PM CDT.

* At 939 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 5 inches of rain 
  have fallen. Additional rainfall amounts of 0.5 to 1.5 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Sallisaw...                        Vian...
  Marble City...                     Brushy Lake State Park...
  Brushy...                          Mc Key...
  Box...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3559 9496 3557 9472 3541 9477 3544 9502
      3545 9502 3545 9503 3546 9503 3546 9504
      3550 9509 3560 9505

FLASH FLOOD...RADAR INDICATED

$$
1 follow-up statement
821 
WGUS74 KTSA 171740
FFSTSA

Flash Flood Statement
National Weather Service Tulsa OK
1240 PM CDT Tue Aug 17 2021

OKC135-171750-
/O.EXP.KTSA.FF.W.0060.000000T0000Z-210817T1745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sequoyah OK-
1240 PM CDT Tue Aug 17 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1245 PM CDT THIS AFTERNOON FOR 
NORTHWESTERN SEQUOYAH COUNTY...

Flood waters have receded. The heavy rain has ended. Flooding is no 
longer expected to pose a threat. Please continue to heed remaining 
road closures.

LAT...LON 3559 9496 3557 9472 3541 9477 3544 9502
      3545 9502 3545 9503 3546 9503 3546 9504
      3550 9509 3560 9505

$$

The office that day

Everything else NWS Tulsa, OK issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 16, 7:14 PM CDTSpecial Weather StatementTSAPawnee46 min
Aug 17, 4:53 AM CDTAreal Flood AdvisoryTSALeFlore3 hr
Aug 17, 6:53 AM CDTAreal Flood AdvisoryTSAAdair, Cherokee, Muskogee, Sequoyah3 hr
Aug 17, 8:27 AM CDTAreal Flood AdvisoryTSAPushmataha3 hr
Aug 17, 9:22 AM CDTAreal Flood AdvisoryTSAChoctaw3 hr

Nearby

Flash Flood Warnings in Oklahoma, 2021Every flash flood warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.