Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 923, NWS Norman, OK

October 21, 2017Garvin County, Pontotoc County, Seminole County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Oct 21, 2017, 9:55 PM CDT for Garvin County, Pontotoc County, Seminole County, Oklahoma. It was in force for 50 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Oct 21, 2017, 9:55 PM CDT (02:55 UTC)
Expired: Oct 21, 2017, 10:45 PM CDT
In force: 50 min
Issued by: NWS Norman, OK
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Garvin County, OK, Pontotoc County, OK, Seminole County, OK

The radar

The Norman radar (KTLX), 82 km from the middle of the area, began a volume at 03:00 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Oct 21, 3:06 PM CDT	Tornado Watch	SPC	7 hr
Oct 21, 7:24 PM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 2.9 hours before the alert went out and 81 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: 1764 J/kg
Mixed-layer CIN: -20 J/kg
Mixed-layer LCL: 974 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 207 m²/s²
0-3 km storm-relative helicity: 226 m²/s²
Significant tornado parameter: 1.9
Supercell composite: 10.8

Open this sounding in Storm Lab

The text

As transmitted.

835 
WUUS54 KOUN 220255
SVROUN
OKC049-123-133-220345-
/O.NEW.KOUN.SV.W.0923.171022T0255Z-171022T0345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Norman OK
955 PM CDT SAT OCT 21 2017

The National Weather Service in Norman has issued a

* Severe Thunderstorm Warning for...
  Northeastern Garvin County in southern Oklahoma...
  Southern Seminole County in east central Oklahoma...
  Pontotoc County in east central Oklahoma...

* Until 1045 PM CDT

* At 955 PM CDT, severe thunderstorms were located along a line
  extending from 6 miles southwest of Konawa to 7 miles west of Roff,
  moving east at 40 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

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

* Locations impacted include...
  Ada, Stratford, Byng, Allen, Roff, Stonewall, Francis, Fitzhugh,
  Sasakwa, Fittstown, Vanoss and Jesse.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms.

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3468 9651 3450 9651 3450 9660 3457 9683
      3459 9683 3460 9693 3464 9693 3464 9708
      3486 9697 3486 9693 3494 9692 3494 9681
      3490 9678 3494 9677 3495 9649 3491 9649
      3490 9643 3492 9641 3468 9641
TIME...MOT...LOC 0255Z 275DEG 33KT 3489 9684 3463 9698 

TORNADO...POSSIBLE
HAIL...<.75IN
WIND...60MPH
 
$$

..speg.

1 follow-up statement

715 
WWUS54 KOUN 220342
SVSOUN

Severe Weather Statement
National Weather Service Norman OK
1042 PM CDT SAT OCT 21 2017

OKC049-123-133-220351-
/O.EXP.KOUN.SV.W.0923.000000T0000Z-171022T0345Z/
Garvin OK-Seminole OK-Pontotoc OK-
1042 PM CDT SAT OCT 21 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN GARVIN...SOUTHERN
SEMINOLE AND PONTOTOC COUNTIES WILL EXPIRE AT 1045 PM CDT...
            
The storms which prompted the warning have weakened below severe 
limits, therefore the warning will be allowed to expire.  However 
gusty winds are still possible with these thunderstorms.

LAT...LON 3468 9651 3450 9651 3450 9660 3457 9683
      3459 9683 3460 9693 3464 9693 3464 9708
      3486 9697 3486 9693 3494 9692 3494 9681
      3490 9678 3494 9677 3495 9649 3491 9649
      3490 9643 3492 9641 3468 9641
TIME...MOT...LOC 0341Z 275DEG 33KT 3485 9634 3459 9648 

$$

..speg.

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 Norman, OK wrote its last area forecast discussion before this severe thunderstorm warning went out at Oct 21, 6:51 PM CDT, 3 hours 4 minutes earlier.

Area forecast discussion, Oct 21, 6:51 PM CDT, 3 hours 4 minutes before

Area Forecast Discussion
National Weather Service Norman OK
651 PM CDT Sat Oct 21 2017

.DISCUSSION...

&&

.AVIATION...
Thunderstorms will move east beyond central, southwest, and north
central Oklahoma before 11 PM. Until then very large hail and
strong wind gusts are likely in some areas. Ceilings will lift
quickly into VFR category when the cold front passes shortly after
thunderstorms. Gusty north winds will subside by mid-day Sunday.

&&

.PREV DISCUSSION... /issued 210 PM CDT Sat Oct 21 2017/

DISCUSSION...
The cold front continues to progress southward this afternoon
across northwestern OK, with a few elevated showers quickly
lifting northeast ahead of it. Stratus is finally starting to mix
out over portions of western and central OK so expect
destabilization through late this afternoon. Initial storm
development should occur sometime around 5 PM along the front in
western and northwestern OK. A few discrete cells will be possible
over southwestern OK and western north TX, with the greatest
potential for a tornado or two near the Red River early this
evening. Otherwise, expect rapid linear merge into a squall line
extending from northern OK into southern and southwestern OK
around 9-10 PM. Wind damage will become a concern during that time
frame. The storms should exit our FA around 1-2 AM.

Tomorrow will be quiet with much cooler and drier air moving into
the Southern Plains. Skies will also clear. A brief warmup is
expected Monday, but another cold front will arrive Tue.
Precipitation is not expected with this front. Again, temperatures
will climb back to a few degrees above normal for Wed and Thu
before a strong cold front arrives overnight Thursday thru Fri.
Some snow will even be possible over northwestern OK Sat AM as a
deep trough sweeps across the central and northern CONUS. Highs on
Friday and Sat are expected to be 10 to 15 degrees below average.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  76  50  68  48 /  50 100   0   0
Hobart OK         79  46  70  47 /  70  90   0   0
Wichita Falls TX  83  50  71  48 /  30  90   0   0
Gage OK           76  40  71  46 /  20  10   0   0
Ponca City OK     77  47  69  46 /  80 100   0   0
Durant OK         80  56  71  48 /  20 100  10   0

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&

09/09/09

Hazardous weather outlook, Oct 21, 9:50 PM CDT, 5 minutes before

Hazardous Weather Outlook...update
National Weather Service Norman OK
950 PM CDT Sat Oct 21 2017

OKZ004>048-050>052-TXZ083>090-221100-
Harper-Woods-Alfalfa-Grant-Kay-Ellis-Woodward-Major-Garfield-
Noble-Roger Mills-Dewey-Custer-Blaine-Kingfisher-Logan-Payne-
Beckham-Washita-Caddo-Canadian-Oklahoma-Lincoln-Grady-McClain-
Cleveland-Pottawatomie-Seminole-Hughes-Harmon-Greer-Kiowa-Jackson-
Tillman-Comanche-Stephens-Garvin-Murray-Pontotoc-Coal-Cotton-
Jefferson-Carter-Johnston-Atoka-Love-Marshall-Bryan-Hardeman-
Foard-Wilbarger-Wichita-Knox-Baylor-Archer-Clay-
950 PM CDT Sat Oct 21 2017

This hazardous weather outlook is for portions of northern...
western...central...and southern Oklahoma...and western north
Texas.

.DAY ONE...Tonight...

.Thunderstorms...
There is an enhanced risk of severe thunderstorms across parts of
central and southern Oklahoma, and adjacent parts of northern Texas.
Slight and marginal risk areas extend slightly to the west of the
enhanced risk area.

Location... The enhanced risk is east of a line from Chandler to
Duncan to Wichita Falls.

Impacts... Damaging wind gusts to around 70 mph and large hail up to
the size of golf balls are the primary hazards. There is a low
potential for tornadoes across parts of southeast Oklahoma.

Timing...
Severe thunderstorms will continue until 2 am.
The most likely time for tornadoes is until midnight.

Discussion... Thunderstorms continue moving east with a cold front
moving through the southeastern half of Oklahoma.

.SPOTTER AND EMERGENCY MANAGEMENT STATEMENT...

Storm spotter groups and emergency management personnel across the
risk areas should prepare for severe weather operations until 2 AM
Sunday.

.DAYS TWO THROUGH SEVEN...Sunday through Friday...

.Thunderstorms...
A few thunderstorms may linger in parts of southeast Oklahoma
Sunday morning before exiting the area.

.Cold/Frost...
Patchy frost and near freezing temperatures may be possible across
portions of Oklahoma late next week.

Get graphics and more details at weather.gov/norman...and follow
our weather forecast office on Twitter and Facebook.

In the hours before

Local storm report, Oct 21, 9:15 PM CDT, 40 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
915 PM CDT SAT OCT 21 2017

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

0844 PM     FLASH FLOOD      STILLWATER              36.12N 97.06W
10/21/2017                   PAYNE              OK   EMERGENCY MNGR

            REPORT OF STREET FLOODING WITH STALLED
            VEHICLES.

&&

MAD

Local storm report, Oct 21, 9:33 PM CDT, 22 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
933 PM CDT SAT OCT 21 2017

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

0850 PM     HAIL             2 S MOORE               35.31N 97.49W
10/21/2017  E1.00 INCH       CLEVELAND          OK   PUBLIC

            SOCIAL MEDIA.

&&

MAD

Local storm report, Oct 21, 9:34 PM CDT, 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
934 PM CDT SAT OCT 21 2017

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

0928 PM     HAIL             5 NE HOLLIDAY           33.87N 98.63W
10/21/2017  E0.75 INCH       WICHITA            TX   TRAINED SPOTTER

&&

MAD

Special weather statement, Oct 21, 9:34 PM CDT, 21 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
934 PM CDT SAT OCT 21 2017

OKZ044-045-TXZ089-090-220300-
Cotton OK-Jefferson OK-Clay TX-Archer TX-
934 PM CDT SAT OCT 21 2017

...SIGNIFICANT WEATHER ADVISORY FOR southeastern Cotton...
Jefferson...Clay and southeastern Archer Counties Until 1000 PM
CDT...

AT 933 PM CDT, strong thunderstorms were along a line extending from
near Byers to 4 miles northeast of Lake Arrowhead to 12 miles east of
Olney, moving northeast at 55 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts to 50 MPH...

LAT...LON 3340 9891 3375 9841 3412 9842 3430 9814
      3429 9814 3429 9757 3395 9771 3393 9773
      3394 9776 3392 9776 3391 9777 3392 9778
      3391 9778 3385 9787 3389 9798 3347 9798
      3347 9842 3340 9842
TIME...MOT...LOC 0233Z 215DEG 49KT 3406 9821 3375 9831 3341 9854

..speg.

Local storm report, Oct 21, 9:44 PM CDT, 11 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
944 PM CDT SAT OCT 21 2017

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

0837 PM     TORNADO          3 NNW GOLDSBY           35.18N 97.50W
10/21/2017                   MCCLAIN            OK   BROADCAST MEDIA

            TORNADO REPORTED NEAR RIVERWIND. DAMAGE
            INCLUDES DOWNED POWERLINES, A SHED
            DESTROYED, A DAMAGED SEMI-TRUCK, AND SEVERAL
            DOWNED TREES.

&&

MAD

Local storm report, Oct 21, 9:49 PM CDT, 6 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
949 PM CDT SAT OCT 21 2017

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

0709 PM     TORNADO          4 E APACHE              34.90N 98.29W
10/21/2017                   CADDO              OK   TRAINED SPOTTER

&&

MAD

The office that day

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

Issued	Product	Office	Counties	Lasted
Oct 21, 7:09 PM CDT	Severe Thunderstorm Warning	OUN	Jackson, Tillman	36 min
Oct 21, 7:10 PM CDT	Tornado Warning	OUN	Caddo	35 min
Oct 21, 7:13 PM CDT	Severe Thunderstorm Warning	OUN	Comanche, Tillman	47 min
Oct 21, 7:22 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Canadian, Grady	38 min
Oct 21, 7:24 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Grady	51 min
Oct 21, 7:27 PM CDT	Tornado Warning	OUN	Caddo, Grady	33 min
Oct 21, 7:34 PM CDT	Flash Flood Warning	OUN	Caddo	116 min
Oct 21, 7:39 PM CDT	Areal Flood Advisory	OUN	Caddo, Comanche	2 hr
Oct 21, 7:40 PM CDT	Special Weather Statement	OUN	Kay, Kingfisher, Logan, Noble	35 min
Oct 21, 7:53 PM CDT	Areal Flood Advisory	OUN	Caddo, Canadian, Grady, Kingfisher, Logan, Oklahoma and 1 more	3 hr
Oct 21, 7:55 PM CDT	Tornado Warning	OUN	Grady, McClain	35 min
Oct 21, 7:56 PM CDT	Severe Thunderstorm Warning	OUN	Canadian, Cleveland, Grady, Oklahoma	49 min
Oct 21, 7:59 PM CDT	Severe Thunderstorm Warning	OUN	Comanche, Cotton, Tillman	46 min
Oct 21, 8:07 PM CDT	Special Weather Statement	OUN	Payne	23 min
Oct 21, 8:10 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, Grady, McClain	50 min
Oct 21, 8:17 PM CDT	Areal Flood Warning	OUN	Caddo, Canadian, Grady	118 min
Oct 21, 8:20 PM CDT	Areal Flood Warning	OUN	Caddo, Canadian, Grady	115 min
Oct 21, 8:33 PM CDT	Special Weather Statement	OUN	Lincoln, Oklahoma, Payne	27 min
Oct 21, 8:33 PM CDT	Severe Thunderstorm Warning	OUN	Grady, Jefferson, Stephens	42 min
Oct 21, 8:36 PM CDT	Areal Flood Advisory	OUN	Lincoln, Logan, Noble, Payne	114 min
Oct 21, 8:37 PM CDT	Tornado Warning	OUN	Cleveland, McClain	23 min
Oct 21, 8:47 PM CDT	Areal Flood Warning	OUN	Canadian, Cleveland, Grady, McClain, Oklahoma	3 hr
Oct 21, 8:48 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, McClain, Oklahoma	42 min
Oct 21, 8:49 PM CDT	Flash Flood Warning	OUN	Canadian, Cleveland, Grady, McClain, Oklahoma	116 min
Oct 21, 8:57 PM CDT	Severe Thunderstorm Warning	OUN	Cotton, Tillman	48 min
Oct 21, 9:02 PM CDT	Flash Flood Warning	OUN	Cleveland, Lincoln, Logan, Oklahoma	118 min
Oct 21, 9:04 PM CDT	Special Weather Statement	OUN	Lincoln, Payne	41 min
Oct 21, 9:10 PM CDT	Severe Thunderstorm Warning	OUN	Carter, Garvin, Grady, Stephens	50 min
Oct 21, 9:17 PM CDT	Areal Flood Advisory	OUN	Carter, Cleveland, Comanche, Cotton, Garvin, Grady and 10 more	118 min
Oct 21, 9:19 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, Lincoln, Oklahoma, Pottawatomie, Seminole	41 min
Oct 21, 9:34 PM CDT	Special Weather Statement	OUN	Jefferson	26 min
Oct 21, 9:38 PM CDT	Tornado Warning	OUN	Pottawatomie, Seminole	37 min
Oct 21, 9:52 PM CDT	Severe Thunderstorm Warning	OUN	Hughes, Lincoln, Pottawatomie, Seminole	38 min
Oct 21, 10:10 PM CDT	Tornado Warning	OUN	Pontotoc	22 min
Oct 21, 10:39 PM CDT	Special Weather Statement	OUN	Carter, Johnston, Love, Marshall, Murray	36 min
Oct 21, 10:47 PM CDT	Special Weather Statement	OUN	Coal, Hughes	28 min
Oct 21, 10:52 PM CDT	Areal Flood Advisory	OUN	Coal, Garvin, Hughes, Murray, Pontotoc, Seminole	53 min
Oct 21, 11:47 PM CDT	Special Weather Statement	OUN	Bryan	28 min
Oct 21, 11:48 PM CDT	Special Weather Statement	OUN	Atoka	27 min
Oct 22, 9:53 AM CDT	River Flood Warning	OUN	Comanche, Cotton	56 hr

Nearby

Severe Thunderstorm Warnings in Oklahoma, 2017 Every severe thunderstorm warning in 2017

Sources

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