Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 336, NWS Tulsa, OK

August 14, 2020LeFlore County, Oklahoma; Sebastian County, Arkansas

NWS Tulsa, OK issued this severe thunderstorm warning at Aug 14, 2020, 4:03 AM CDT for LeFlore County, Oklahoma; Sebastian County, Arkansas. It was in force for 27 min. 1 report 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 14, 2020, 4:03 AM CDT (09:03 UTC)
Expired: Aug 14, 2020, 4:30 AM CDT
In force: 27 min
Issued by: NWS Tulsa, OK
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Sebastian County, AR, LeFlore County, OK

The radar

The Western Arkansas radar (KSRX), 25 km from the middle of the area, began a volume at 09:07 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

Time	Report	Where	Remark
Aug 14, 4:05 AM CDT	TSTM WND DMG	Lavaca, AR	NUMEROUS TREES DOWN ACROSS TOWN RELAYED BY COUNTY EMERGENCY MANAGEMENT.

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

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this severe thunderstorm warning; the first came 2 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Springfield, MO (KSGF), launched 00:00Z, 9.1 hours before the alert went out and 205 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 793 J/kg
Mixed-layer CIN: -38 J/kg
Mixed-layer LCL: 1489 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: -3 m²/s²
0-3 km storm-relative helicity: 52 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.5

Open this sounding in Storm Lab

The text

As transmitted.

322 
WUUS54 KTSA 140903
SVRTSA
ARC131-OKC079-140945-
/O.NEW.KTSA.SV.W.0336.200814T0903Z-200814T0945Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Tulsa OK
403 AM CDT Fri Aug 14 2020

The National Weather Service in Tulsa has issued a

* Severe Thunderstorm Warning for...
  Sebastian County in west central Arkansas...
  East central Le Flore County in southeastern Oklahoma...

* Until 445 AM CDT.

* At 403 AM CDT, severe thunderstorms were located along a line
  extending from near Bloomer to 2 miles northeast of Midland to 2
  miles southwest of Cameron, moving southeast at 35 mph.

  HAZARD...60 mph wind gusts and penny size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations in or near the path include...
  Poteau...                         Greenwood...
  Lavaca...                         Hackett...
  Hartford...                       Huntington...
  Midland...                        Cameron...
  Bloomer...                        Washburn...
  Excelsior...                      Burnville...
  Shady Point...                    Rock Island...
  Patterson...                      Arkola...
  Crossroads...                     Witcherville...
  Dayton...                         Milltown...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Wind damage with these storms will occur before any rain or
lightning. Do not wait for the sound of thunder before taking cover.
SEEK SHELTER IMMEDIATELY inside a sturdy structure and stay away from
windows.

&&

LAT...LON 3514 9403 3514 9414 3510 9414 3506 9425
      3506 9423 3497 9424 3495 9434 3496 9437
      3494 9439 3493 9445 3485 9445 3485 9451
      3515 9467 3520 9437 3537 9414 3530 9408
      3522 9408 3520 9405 3521 9405 3521 9403
TIME...MOT...LOC 0903Z 321DEG 31KT 3532 9414 3513 9433 3510 9455 

HAIL...0.75IN
WIND...60MPH
 
$$

1 follow-up statement

375 
WWUS54 KTSA 140930
SVSTSA

Severe Weather Statement
National Weather Service Tulsa OK
430 AM CDT Fri Aug 14 2020

ARC131-OKC079-140939-
/O.CAN.KTSA.SV.W.0336.000000T0000Z-200814T0945Z/
Sebastian AR-Le Flore OK-
430 AM CDT Fri Aug 14 2020

...THE SEVERE THUNDERSTORM WARNING FOR SEBASTIAN AND EAST CENTRAL LE
FLORE COUNTIES IS CANCELLED...
    
The storms which prompted the warning have moved out of the area.
Therefore the warning has been cancelled.  However gusty winds are
still possible with lingering thunderstorms across eastern Le Flore
and southern Sebastian counties.

LAT...LON 3514 9403 3514 9414 3510 9414 3506 9425
      3506 9423 3497 9424 3495 9434 3496 9437
      3494 9439 3493 9445 3485 9445 3485 9451
      3515 9467 3520 9437 3537 9414 3530 9408
      3522 9408 3520 9405 3521 9405 3521 9403
TIME...MOT...LOC 0928Z 321DEG 31KT 3515 9397 3496 9416 3493 9438 

$$

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at Aug 14, 12:18 AM CDT, 3 hours 45 minutes earlier.

Area forecast discussion, Aug 14, 12:18 AM CDT, 3 hours 45 minutes before

Area Forecast Discussion
National Weather Service Tulsa OK
1218 AM CDT Fri Aug 14 2020

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
VFR conditions at this time, although expect thunderstorms to
develop around 07-08Z across northwest Arkansas with the
activity moving south and southeast through the night. Expect
storms to remain a bit east of the eastern OK sites, with
MVRF cigs/vsbys possible mainly for the northwestern AR sites
in and near storms. Most of the convection should diminish
toward 14-15Z.

&&

.PREV DISCUSSION... /Issued 941 PM CDT Thu Aug 13 2020/

DISCUSSION...
Main update item for this evening is adding a flash flood watch
effective from midnight to 8 am for parts of eastern Oklahoma and
northwest Arkansas. Elevated boundary setting up a little further
east tonight, with a resultant heavy rain axis across far eastern
Oklahoma extending southeast into parts of northwest Arkansas.
The swath of heaviest rainfall is expected to remain fairly
narrow, however localized amounts up to 4 inches will be possible.

Remaining forecast elements look in good shape, sans some very
minor tweaks to overnight QPF.

Updated ZFP/PFM/AFM and new FFA already sent.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   74  93  70  88 /   0   0  10  10
FSM   74  94  72  92 /   0  10  10  10
MLC   74  95  73  89 /   0  10  10  10
BVO   72  91  66  86 /  10  10  10  10
FYV   70  89  67  86 /   0  10  10  10
BYV   69  90  67  88 /   0  10  10  10
MKO   74  93  70  88 /   0  10  10  10
MIO   71  90  65  86 /   0  10  10  10
F10   73  93  70  87 /   0   0  10  10
HHW   75  97  75  95 /   0   0  10  10

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Flash Flood Watch until 8 AM CDT this morning for OKZ062-063-068-
     069-072.

AR...Flash Flood Watch until 8 AM CDT this morning for ARZ010-019-020-
     029.

&&

AVIATION.....18

Hazardous weather outlook, Aug 13, 4:37 PM CDT, 11 hours 26 minutes before

Hazardous Weather Outlook
National Weather Service Tulsa OK
437 PM CDT Thu Aug 13 2020

ARZ001-002-010-011-019-020-029-OKZ049-053>076-141015-
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 PM CDT Thu Aug 13 2020

This Outlook is for Northwest and West Central Arkansas as well as
much of Eastern Oklahoma.

.DAY ONE...Through Tonight.

SEVERE THUNDERSTORM.
	RISK...Limited.
	AREA...Eastern Oklahoma and Northwest Arkansas.
	ONSET...Around Midnight.

FLASH FLOOD.
	RISK...Limited.
	AREA...Northeast Oklahoma and northwest Arkansas.
	ONSET...Around Midnight.

DANGEROUS HEAT.
	RISK...Elevated.
	AREA...Portions of eastern Oklahoma.
	ONSET...Ongoing.

DISCUSSION...

Ongoing hot and humid conditions will result in heat index values
around 105 degrees. Conditions will improve after sunset.

Multiple clusters of strong thunderstorms will likely develop again
tonight across portions of northeast Oklahoma and northwest
Arkansas. A few of these storms could be severe with marginally
severe hail and damaging winds.

In addition, very heavy rainfall is likely in the stronger storms
and localized flash flooding may become the main concern into early
Friday morning given the slow storm motions expected.  A flash flood
watch may be needed for portions of the area later as the axis of
heavier rainfall becomes more certain.

SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT...
Activation of the Regional Spotter Network Possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.
FRIDAY...Thunderstorm and Dangerous Heat Potential.
SATURDAY...Dangerous Heat Potential.
SUNDAY and MONDAY...Thunderstorm Potential.
TUESDAY and WEDNESDAY...No Hazards.

EXTENDED DISCUSSION...

Scattered thunderstorms are likely to be ongoing Friday morning
across portions of eastern Oklahoma and northwest Arkansas with a
continued threat for heavy rainfall. These storms will gradually
weaken during the morning hours with hot and humid conditions
developing both Friday and Saturday afternoons. A slight chance of
thunderstorms will return Sunday and Monday as a weak cold front
gradually pushes through the region. Dry and cooler weather is
expected for the first part of next week.

weather.gov/tulsa contains additional information.

In the hours before

Special weather statement, Aug 14, 1:40 AM CDT, 2 hours 23 minutes before

Special Weather Statement
National Weather Service Tulsa OK
140 AM CDT Fri Aug 14 2020

ARZ010-OKZ068-069-140730-
Washington AR-Adair OK-Cherokee OK-
140 AM CDT Fri Aug 14 2020

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL WASHINGTON...
NORTHERN ADAIR AND EASTERN CHEROKEE COUNTIES UNTIL 230 AM CDT...

At 139 AM CDT, a strong thunderstorm was located 5 miles east of
Scraper, moving southeast at 20 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations in or near the path include...
Westville...                      Proctor...
Christie...                       Scraper...
Cincinnati...                     Baron...
Summers...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3604 9490 3616 9478 3604 9444 3581 9459
TIME...MOT...LOC 0639Z 304DEG 18KT 3608 9476

Special weather statement, Aug 14, 2:07 AM CDT, 1 hour 56 minutes before

Special Weather Statement
National Weather Service Tulsa OK
207 AM CDT Fri Aug 14 2020

ARZ010-OKZ068-069-140745-
Washington AR-Adair OK-Cherokee OK-
207 AM CDT Fri Aug 14 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN WASHINGTON...ADAIR
AND EAST CENTRAL CHEROKEE COUNTIES UNTIL 245 AM CDT...

At 207 AM CDT, a strong thunderstorm was located 3 miles north of
Proctor, moving southeast at 30 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations in or near the path include...
Stilwell...                       Westville...
Eldon...                          Adair State Park...
Proctor...                        Christie...
Strickler...                      Maryetta...
Bunch...                          Baron...
Clyde...                          Canehill...
Morrow...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3597 9492 3611 9478 3585 9427 3565 9477
TIME...MOT...LOC 0707Z 307DEG 28KT 3601 9479

Local storm report, Aug 14, 3:57 AM CDT, 6 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TULSA OK
357 AM CDT FRI AUG 14 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0343 AM     TSTM WND GST     FORT SMITH              35.39N 94.40W
08/14/2020  E70 MPH          SEBASTIAN          AR   TRAINED SPOTTER

            SPOTTER REPORTS AN ESTIMATED WIND GUST OF 65 TO 70MPH IN
            DOWNTOWN FT. SMITH.

&&

SNIDER

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 13, 9:32 PM CDT	Flash Flood Watch	TSA	Adair, Cherokee, Craig, Delaware, Mayes, Ottawa	12 hr
Aug 14, 1:40 AM CDT	Special Weather Statement	TSA	Adair	50 min
Aug 14, 2:07 AM CDT	Special Weather Statement	TSA	Adair	38 min
Aug 14, 2:25 AM CDT	Areal Flood Advisory	TSA	Adair, Cherokee	3 hr
Aug 14, 2:42 AM CDT	Severe Thunderstorm Warning	TSA	Adair, Sequoyah	48 min
Aug 14, 3:06 AM CDT	Severe Thunderstorm Warning	TSA	Adair, Sequoyah	39 min
Aug 14, 3:13 AM CDT	Heat Advisory	TSA	Choctaw, Craig, Creek, Haskell, Latimer, McIntosh and 12 more	17 hr
Aug 14, 3:16 AM CDT	Flash Flood Warning	TSA	Adair, Cherokee	4 hr
Aug 14, 3:35 AM CDT	Severe Thunderstorm Warning	TSA	LeFlore, Sequoyah	40 min
Aug 14, 5:14 AM CDT	Areal Flood Advisory	TSA	Craig, Delaware, Mayes	3 hr
Aug 14, 5:21 AM CDT	Areal Flood Advisory	TSA	Adair, Cherokee	3 hr
Aug 14, 5:39 AM CDT	Special Weather Statement	TSA	Delaware	36 min
Aug 14, 6:16 AM CDT	Special Weather Statement	TSA	Craig, Delaware	44 min
Aug 14, 6:26 AM CDT	Flash Flood Warning	TSA	Adair, Cherokee, Craig, Delaware, Mayes	3 hr
Aug 14, 6:34 AM CDT	Flash Flood Warning	TSA	Adair, LeFlore, Sequoyah	3 hr
Aug 14, 6:56 AM CDT	Special Weather Statement	TSA	Craig, Delaware	34 min
Aug 14, 7:03 AM CDT	Flash Flood Warning	TSA	Craig, Delaware, Mayes, Ottawa	3 hr
Aug 14, 7:31 AM CDT	Special Weather Statement	TSA	Delaware	59 min
Aug 14, 9:08 AM CDT	Areal Flood Warning	TSA	Adair, Cherokee, Delaware	6 hr
Aug 14, 9:14 AM CDT	Areal Flood Warning	TSA	Adair, Sequoyah	6 hr
Aug 14, 9:20 AM CDT	Areal Flood Warning	TSA	Craig, Delaware, Mayes	6 hr
Aug 14, 2:16 PM CDT	Heat Advisory	TSA	Adair, Cherokee, Choctaw, Craig, Creek, Delaware and 16 more	30 hr
Aug 14, 4:18 AM CDT	Special Weather Statement	TSA	Logan	27 min
Aug 14, 4:33 AM CDT	Areal Flood Advisory	TSA	Sebastian	3 hr

Nearby

Severe Thunderstorm Warnings in Oklahoma, 2020 Severe Thunderstorm Warnings in Arkansas, 2020 Every severe thunderstorm warning in 2020

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.