Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 903, NWS Norman, OK

October 21, 2017Caddo County, Comanche County, Grady County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Oct 21, 2017, 6:41 PM CDT for Caddo County, Comanche County, Grady County, Oklahoma. It was in force for 49 min. 2 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: Oct 21, 2017, 6:41 PM CDT (23:41 UTC)
Expired: Oct 21, 2017, 7:30 PM CDT
In force: 49 min
Issued by: NWS Norman, OK
Area: Storm-based polygon
Tornado: Possible
Hail: 2.75 in
Wind: 70.0 mph

Counties Caddo County, OK, Comanche County, OK, Grady County, OK

The radar

The Altus AFB radar (KFDR), 82 km from the middle of the area, began a volume at 23:43 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
Oct 21, 7:09 PM CDT	TORNADO	4 E Apache, OK
Oct 21, 7:15 PM CDT	TSTM WND GST 61	3 Sse Stecker, OK

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 34 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 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

The nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 11.7 hours before the alert went out and 94 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: 725 J/kg
Mixed-layer CIN: -149 J/kg
Mixed-layer LCL: 642 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 231 m²/s²
0-3 km storm-relative helicity: 252 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

As transmitted.

770 
WUUS54 KOUN 212341
SVROUN
OKC015-031-051-220030-
/O.NEW.KOUN.SV.W.0903.171021T2341Z-171022T0030Z/

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

The National Weather Service in Norman has issued a

* Severe Thunderstorm Warning for...
  North central Comanche County in southwestern Oklahoma...
  West central Grady County in central Oklahoma...
  Southern Caddo County in southwestern Oklahoma...

* Until 730 PM CDT

* At 641 PM CDT, a severe thunderstorm was located near Boone, moving
  northeast at 35 mph.

  This is a very dangerous storm. 

  HAZARD...Baseball size hail and 70 mph wind gusts. 

  SOURCE...Radar indicated. 

  IMPACT...People and animals outdoors will be severely injured. 
           Expect shattered windows, extensive damage to roofs, 
           siding, and vehicles. 

* Locations impacted include...
  Anadarko, Elgin, Apache, Fletcher, Cyril, Verden, Cement, Medicine
  Park, Meers, Lake Lawtonka, Boone, Lake Ellsworth, Ninnekah,
  Stecker, Laverty and eastern Wichita Mountains Wildlife Refuge.

This includes Interstate 44 between mile markers 54 and 74.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This is a dangerous storm. Prepare immediately for large destructive
hail capable of producing significant damage. People outside should
move to shelter inside a strong building,  and stay away from
windows.

&&

LAT...LON 3471 9849 3479 9861 3492 9860 3518 9828
      3509 9808 3491 9796
TIME...MOT...LOC 2341Z 232DEG 29KT 3484 9846 

TORNADO...POSSIBLE
HAIL...2.75IN
WIND...70MPH
 
$$

KURTZ

1 follow-up statement

419 
WWUS54 KOUN 212351
SVSOUN

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

OKC015-031-051-220030-
/O.CON.KOUN.SV.W.0903.000000T0000Z-171022T0030Z/
Comanche OK-Grady OK-Caddo OK-
651 PM CDT SAT OCT 21 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 730 PM CDT
FOR NORTH CENTRAL COMANCHE...WEST CENTRAL GRADY AND SOUTHERN CADDO
COUNTIES...

At 651 PM CDT, a severe thunderstorm was located near Apache, moving
northeast at 30 mph.

This is a very dangerous storm.

HAZARD...Baseball size hail and 70 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...People and animals outdoors will be severely injured. 
         Expect shattered windows, extensive damage to roofs, 
         siding, and vehicles. 

Locations impacted include...
Anadarko, Apache, Fletcher, Cyril, Verden, Cement, Lake Ellsworth,
Boone, Lake Lawtonka, Ninnekah, Stecker and Laverty.

This includes Interstate 44 between mile markers 55 and 74.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

A tornado watch remains in effect for the warned area. Tornadoes can
develop quickly from severe thunderstorms.

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

This is a dangerous storm. Prepare immediately for large destructive
hail capable of producing significant damage. People outside should
move to a shelter, inside a strong building and away from windows.

&&

LAT...LON 3474 9844 3479 9857 3486 9859 3496 9854
      3518 9828 3509 9808 3491 9796
TIME...MOT...LOC 2351Z 227DEG 26KT 3490 9839 

HAIL...2.75IN
WIND...70MPH
 
$$

KURTZ

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, 2:10 PM CDT, 4 hours 31 minutes earlier.

Area forecast discussion, Oct 21, 2:10 PM CDT, 4 hours 31 minutes before

Area Forecast Discussion
National Weather Service Norman OK
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  50  68  48  77 / 100   0   0   0
Hobart OK         46  70  47  78 /  90   0   0   0
Wichita Falls TX  50  71  48  80 /  90   0   0   0
Gage OK           40  71  46  75 /  10   0   0   0
Ponca City OK     47  69  46  75 / 100   0   0   0
Durant OK         56  71  48  80 / 100  10   0   0

&&

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

04/03

Hazardous weather outlook, Oct 21, 6:00 PM CDT, 41 minutes before

Hazardous Weather Outlook
National Weather Service Norman OK
600 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-
600 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
north central, central, and southern Oklahoma, and adjacent parts of
northern Texas. A slight and marginal risk cover much of the rest of
the area.

Location...
The enhanced risk is near and southeast of a line from
Enid to Clinton, Altus, and Seymour Texas. This includes places like
Ponca City, Enid, Lawton, Oklahoma City metro, Ada, Ardmore, and
Wichita Falls.

Impacts...
Damaging wind gusts to around 80 mph and large hail up to the size
of tennis balls are the primary hazards. There is a low potential
for tornadoes across parts of central and southern Oklahoma, and
adjacent parts of northern Texas.

Timing...
Severe thunderstorms will continue until 2 am.
The most likely time for tornadoes is until 9 PM.

Discussion...
Thunderstorms continue forming along a cold front moving southeast
across Oklahoma. Large hail is the main hazard until mid-evening
after which damaging winds will become the main hazard. Isolated
wind gusts up to 80 mph are possible.

The tornado potential, particularly in southwest Oklahoma, will
decrease late this evening.

.SPOTTER AND EMERGENCY MANAGEMENT STATEMENT...

Storm spotter groups and emergency management personnel across the
risk areas should prepare for severe weather operations late this
afternoon and tonight.

.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, 6:20 PM CDT, 21 minutes before

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

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

0600 PM     HAIL             2 WNW INDIAHOMA         34.63N 98.79W
10/21/2017  E3.00 INCH       COMANCHE           OK   STORM CHASER

            LOCATION APPROXIMATE.

&&

MAD

Local storm report, Oct 21, 6:27 PM CDT, 14 minutes before

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

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

0619 PM     TSTM WND DMG     2 W CACHE               34.62N 98.67W
10/21/2017                   COMANCHE           OK   AMATEUR RADIO

            POWERPOLES PARTIALLY DOWN.

&&

MAD

Local storm report, Oct 21, 6:30 PM CDT, 11 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE NORMAN OK
630 PM CDT SAT OCT 21 2017

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

0610 PM     TSTM WND DMG     2 W CACHE               34.62N 98.67W
10/21/2017                   COMANCHE           OK   AMATEUR RADIO

            POWERPOLES PARTIALLY DOWN. TIME ESTIMATED BY
            RADAR.

&&

MAD

Local storm report, Oct 21, 6:32 PM CDT, 9 minutes before

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

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

0620 PM     HAIL             LAKE LAWTONKA           34.76N 98.51W
10/21/2017  E0.88 INCH       COMANCHE           OK   AMATEUR RADIO

&&

MAD

Special weather statement, Oct 21, 6:33 PM CDT, 8 minutes before

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

OKZ016-017-022-023-220000-
Washita OK-Caddo OK-Custer OK-Blaine OK-
633 PM CDT SAT OCT 21 2017

...SIGNIFICANT WEATHER ADVISORY FOR northeastern Washita...
northwestern Caddo...southeastern Custer and southern Blaine Counties
Until 700 PM CDT...

AT 632 PM CDT, strong thunderstorms were along a line extending from
6 miles southeast of Fay to 6 miles northeast of Colony, moving east
at 45 MPH. Another strong storm was located near Corn.

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

LAT...LON 3576 9871 3594 9821 3573 9821 3572 9831
      3539 9831 3526 9899
TIME...MOT...LOC 2332Z 251DEG 39KT 3573 9859 3544 9862

..speg.

Special weather statement, Oct 21, 6:41 PM CDT, 0 minutes before

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

OKZ007-008-012-013-220015-
Garfield OK-Kay OK-Grant OK-Noble OK-
641 PM CDT SAT OCT 21 2017

...SIGNIFICANT WEATHER ADVISORY FOR eastern Garfield...Kay...eastern
Grant and Noble Counties Until 715 PM CDT...

AT 640 PM CDT, strong thunderstorms were along a line extending from
3 miles north of Lamont to near Covington, moving northeast at 35
MPH.

HAZARDS INCLUDE...
Wind gusts over 50 MPH...
Minor flooding in areas of poor drainage...

LAT...LON 3678 9675 3677 9682 3674 9683 3675 9689
      3668 9693 3670 9704 3668 9706 3660 9704
      3659 9706 3658 9700 3660 9691 3658 9689
      3655 9690 3653 9699 3651 9703 3635 9703
      3619 9774 3700 9766 3700 9675
TIME...MOT...LOC 2340Z 234DEG 32KT 3674 9757 3627 9760

..speg.

The office that day

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

Issued	Product	Office	Counties	Lasted
Oct 21, 3:28 PM CDT	Special Weather Statement	OUN	Tillman	32 min
Oct 21, 3:37 PM CDT	Severe Thunderstorm Warning	OUN	Comanche, Jackson, Kiowa, Tillman	53 min
Oct 21, 4:04 PM CDT	Special Weather Statement	OUN	Roger Mills	26 min
Oct 21, 4:05 PM CDT	Special Weather Statement	OUN	Custer	40 min
Oct 21, 4:06 PM CDT	Severe Thunderstorm Warning	OUN	Jackson, Tillman	39 min
Oct 21, 4:08 PM CDT	Severe Thunderstorm Warning	OUN	Kiowa, Washita	52 min
Oct 21, 4:21 PM CDT	Special Weather Statement	OUN	Beckham	24 min
Oct 21, 4:25 PM CDT	Severe Thunderstorm Warning	OUN	Blaine, Dewey	50 min
Oct 21, 4:29 PM CDT	Severe Thunderstorm Warning	OUN	Beckham, Roger Mills	46 min
Oct 21, 4:31 PM CDT	Severe Thunderstorm Warning	OUN	Dewey, Ellis, Roger Mills	44 min
Oct 21, 4:42 PM CDT	Severe Thunderstorm Warning	OUN	Comanche, Jackson, Kiowa, Tillman	48 min
Oct 21, 4:45 PM CDT	Severe Thunderstorm Warning	OUN	Blaine, Caddo, Canadian, Custer, Kiowa, Washita	45 min
Oct 21, 4:48 PM CDT	Special Weather Statement	OUN	Roger Mills	27 min
Oct 21, 5:09 PM CDT	Severe Thunderstorm Warning	OUN	Beckham, Roger Mills	37 min
Oct 21, 5:13 PM CDT	Severe Thunderstorm Warning	OUN	Alfalfa, Garfield, Grant, Major	47 min
Oct 21, 5:18 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Jackson, Kiowa, Washita	42 min
Oct 21, 5:24 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Kiowa, Tillman	51 min
Oct 21, 5:27 PM CDT	Severe Thunderstorm Warning	OUN	Jackson, Tillman	48 min
Oct 21, 5:28 PM CDT	Severe Thunderstorm Warning	OUN	Blaine, Custer, Dewey	47 min
Oct 21, 5:30 PM CDT	Severe Thunderstorm Warning	OUN	Custer, Washita	45 min
Oct 21, 5:37 PM CDT	Special Weather Statement	OUN	Major	38 min
Oct 21, 5:44 PM CDT	Tornado Warning	OUN	Comanche, Tillman	31 min
Oct 21, 5:49 PM CDT	Severe Thunderstorm Warning	OUN	Jackson, Tillman	41 min
Oct 21, 5:54 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Kiowa, Washita	51 min
Oct 21, 6:09 PM CDT	Special Weather Statement	OUN	Garfield, Grant	36 min
Oct 21, 6:09 PM CDT	Tornado Warning Tornado observed	OUN	Caddo, Comanche	36 min
Oct 21, 6:25 PM CDT	Severe Thunderstorm Warning	OUN	Comanche, Kiowa, Tillman	50 min
Oct 21, 6:29 PM CDT	Areal Flood Advisory	OUN	Caddo, Comanche, Kiowa, Tillman	3 hr
Oct 21, 6:33 PM CDT	Special Weather Statement	OUN	Blaine	27 min
Oct 21, 6:41 PM CDT	Special Weather Statement	OUN	Kay, Noble	34 min
Oct 21, 6:43 PM CDT	Areal Flood Advisory	OUN	Garfield, Grant, Kay, Noble	3 hr
Oct 21, 6:50 PM CDT	Flash Flood Warning	OUN	Comanche	3 hr
Oct 21, 6:55 PM CDT	Special Weather Statement	OUN	Kingfisher	35 min
Oct 21, 6:57 PM CDT	Severe Thunderstorm Warning	OUN	Kay, Noble	48 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.