Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 167, NWS Norman, OK

April 21, 2017Atoka County, Bryan County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Apr 21, 2017, 6:58 PM CDT for Atoka County, Bryan County, Oklahoma. It was in force for 32 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Apr 21, 2017, 6:58 PM CDT (23:58 UTC)
Expired: Apr 21, 2017, 7:30 PM CDT
In force: 32 min
Issued by: NWS Norman, OK
Area: Storm-based polygon
Tornado: Possible
Hail: 1.75 in
Wind: 60.0 mph

Counties Atoka County, OK, Bryan County, OK

The radar

The Norman radar (KTLX), 166 km from the middle of the area, began a volume at 00:00 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.

The watch it was issued in

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

Issued	Product	Office	Lasted
Apr 21, 4:40 PM CDT	Tornado Watch	SPC	8 hr

The nearest sounding before it

Fort Worth, TX (KFWD), launched 12:00Z, 12.0 hours before the alert went out and 183 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: 106 J/kg
Mixed-layer CIN: -396 J/kg
Mixed-layer LCL: 1056 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 86 m²/s²
0-3 km storm-relative helicity: 85 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

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 Apr 21, 6:29 PM CDT, 29 minutes earlier.

Area forecast discussion, Apr 21, 6:29 PM CDT, 29 minutes before

Area Forecast Discussion
National Weather Service Norman OK
629 PM CDT Fri Apr 21 2017

.DISCUSSION...
The 00Z aviation discussion follows....

&&

.AVIATION...
As a departing upper-level wave sets off more thunderstorms across
south-central and southeast Oklahoma this evening, our TAF sites
will remain west of this action. However, a few showers will still
be possible, particularly northeast of KAVK-KEND-KOKC-KSNL this
evening, and again tomorrow afternoon. These showers may briefly
cause visibilities to drop below 3 miles at times. Otherwise,
expect brisk and gusty north winds across the region as a cooler
airmass advances into Oklahoma and north Texas. The low clouds
that currently cover most of Oklahoma and parts of north Texas
will begin to break up this evening, but most of these breaks will
be quite temporary. There will be a general trend toward more
breaks and gradually increasing ceiling heights as the morning
progresses on Saturday, and this trend will continue into the
afternoon. By late afternoon, most of the region should have
ceilings in the VFR range, or no ceiling at all. Winds will begin
to diminish toward the end of this forecast period (23/0000Z).

CmS
&&

.PREV DISCUSSION... /issued 238 PM CDT Fri Apr 21 2017/

DISCUSSION...
Scattered showers and some storms will continue to develop and
move across portions of the fa the rest of this afternoon and
evening. A few strong to severe storms still remain possible along
with some locally heavy rain with any storms. The rain has ended
for far western portions of the fa and that trend is expected to
slowly continue from west to east through this evening. With
several inches of rain in some areas earlier today and ongoing
flooding issues, any additional heavy rain could cause/exacerbate
flooding conditions in those areas. Also monitoring to see the
response of rivers and creeks as the water runs off so will leave
the Flood Watch as is for now but could cancel part of the watch
over the next hour or so if trends continue in some areas.

Saturday will probably feel chilly for some with gusty north winds
and highs expected to only climb into the 50s and 60s. A cold
night is expected Saturday night with lows in the mid to upper 30s
possible across the NW third or so of the fa. Frost may also be
possible in this area due to these low temperatures combined with
fairly light winds and clear skies.

Southerly winds will return to the area Sunday. Temperatures will
also warm up again early next week. Models show a weak shortwave
moving across the Central U.S. Tuesday which will bring a low
chance for showers and thunderstorms to northern parts of the area
Tuesday night into Wednesday. Models then diverge late next week
as to timing, path, and strength of an upper trough that would
affect the area. The ECMWF shows the bulk of the showers/storms
would affect the area Thursday while the GFS would show the most
widespread/strongest activity not occuring until Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  45  58  40  69 /  20  10   0   0
Hobart OK         43  61  38  70 /  10   0   0   0
Wichita Falls TX  46  64  42  72 /  20  10   0   0
Gage OK           39  60  37  70 /  10   0   0   0
Ponca City OK     44  57  37  70 /  50  10   0   0
Durant OK         51  60  44  71 /  80  10   0   0

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch until midnight CDT tonight for OKZ018>020-024>026-
     030-031.

TX...None.
&&

23/03/23

Hazardous weather outlook, Apr 21, 3:36 PM CDT, 3 hours 22 minutes before

Hazardous Weather Outlook
National Weather Service Norman OK
336 PM CDT Fri Apr 21 2017

OKZ004>048-050>052-TXZ083>090-220700-
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-
336 PM CDT Fri Apr 21 2017

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

.DAY ONE...Through Tonight...

.Thunderstorms...
There is an Enhanced Risk of severe thunderstorms this afternoon
and this evening across parts of southern Oklahoma.

Location...
The Enhanced Risk area is south and east of a line from Centrahoma
to Sulphur and Henrietta...Texas.

A Slight Risk area surrounds the Enhanced Risk area and is
southeast of a line from Holdenville, Wynnewood and Wichita Falls,
Texas.

A Marginal Risk for severe thunderstorms exists to the north of
the Slight Risk and is southeast of a line from Norman, to Lawton
and Vernon, Texas.

Timing...
Now through 10 pm this evening.

Impacts...
Damaging winds up to 70 mph.

Large hail up to golf balls, especially across south central
and southeast Oklahoma this afternoon and early evening.

A low risk for tornadoes exists this afternoon and evening
across parts of south central and southeast Oklahoma.

Discussion...
A warm and moist airmass remains in place across south central
and southeastern Oklahoma. By late afternoon, a nearly stationary
frontal boundary, will begin to push southward across south
central and southeastern Oklahoma. As this occurs, widely
scattered thunderstorms may develop along and ahead of the front.
Instability and deep layer shear will support the risk of large
hail and damaging wind gusts. There is also a low chance of a
tornado or two.

The risk of severe storms is expected to end by 9 pm.

.SPOTTER AND EMERGENCY MANAGEMENT STATEMENT...
Storm spotter groups and emergency management personnel across
risk areas should prepare for severe weather operations today and
this evening.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday...

.Thunderstorms...
Thunderstorm chances are expected to return next Wednesday night
into Thursday, with severe storms possible.

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

In the hours before

Special weather statement, Apr 21, 4:20 PM CDT, 2 hours 38 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
420 PM CDT FRI APR 21 2017

OKZ031-042-212145-
Pontotoc OK-Seminole OK-
420 PM CDT FRI APR 21 2017

...SIGNIFICANT WEATHER ADVISORY FOR northern Pontotoc and south
central Seminole Counties Until 445 PM CDT...

AT 419 PM CDT, a strong thunderstorm was located 5 miles east of
Vanoss, moving northeast at 35 MPH.

HAZARDS INCLUDE...
Hail up to one-half inch diameter...
Wind gusts to 40 MPH...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

&&

LAT...LON 3470 9683 3481 9691 3497 9654 3479 9640
      3478 9641
TIME...MOT...LOC 2119Z 244DEG 32KT 3477 9678

30

Special weather statement, Apr 21, 5:20 PM CDT, 1 hour 38 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
520 PM CDT FRI APR 21 2017

OKZ044-045-TXZ090-212245-
Cotton OK-Jefferson OK-Clay TX-
520 PM CDT FRI APR 21 2017

...SIGNIFICANT WEATHER ADVISORY FOR southeastern Cotton...western
Jefferson and northeastern Clay Counties Until 545 PM CDT...

AT 518 PM CDT, a strong thunderstorm was located near Byers, moving
east at 35 MPH.

HAZARDS INCLUDE...
Hail up to one-half inch diameter...
Wind gusts to 40 MPH...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

&&

LAT...LON 3397 9829 3417 9829 3420 9775 3392 9777
TIME...MOT...LOC 2218Z 271DEG 32KT 3408 9821

30

Local storm report, Apr 21, 6:03 PM CDT, 55 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
603 PM CDT FRI APR 21 2017

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

0603 PM     HAIL             COLEMAN                 34.27N 96.42W
04/21/2017  E1.25 INCH       JOHNSTON           OK   TRAINED SPOTTER

&&

RBARNES

Local storm report, Apr 21, 6:22 PM CDT, 36 minutes before

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Special weather statement, Apr 21, 6:31 PM CDT, 27 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
631 PM CDT FRI APR 21 2017

OKZ041-042-046-047-220000-
Carter OK-Pontotoc OK-Johnston OK-Murray OK-
631 PM CDT FRI APR 21 2017

...SIGNIFICANT WEATHER ADVISORY FOR east central Carter...
southwestern Pontotoc...northwestern Johnston and eastern Murray
Counties Until 700 PM CDT...

AT 631 PM CDT, a strong thunderstorm was located near Davis, moving
east at 35 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts to 40 MPH...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

&&

LAT...LON 3436 9718 3451 9717 3451 9714 3452 9715
      3452 9716 3455 9716 3459 9680 3434 9680
TIME...MOT...LOC 2331Z 273DEG 32KT 3446 9709

30

Special weather statement, Apr 21, 6:57 PM CDT, 1 minute before

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  <meta name="viewport" content="width=device-width, initial-scale=1">
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  <link rel="stylesheet" href="index.css">
</head>
<body>
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    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
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The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 9:53 PM CDT	Severe Thunderstorm Warning	OUN	Harmon, Jackson	52 min
Apr 20, 10:10 PM CDT	Special Weather Statement	OUN	Greer	50 min
Apr 20, 10:37 PM CDT	Severe Thunderstorm Warning	OUN	Jackson, Tillman	38 min
Apr 20, 10:47 PM CDT	Special Weather Statement	OUN	Kiowa	43 min
Apr 20, 11:08 PM CDT	Severe Thunderstorm Warning	OUN	Jackson, Tillman	67 min
Apr 20, 11:23 PM CDT	Severe Thunderstorm Warning	OUN	Jackson, Kiowa	52 min
Apr 20, 11:28 PM CDT	Special Weather Statement	OUN	Custer	47 min
Apr 20, 11:29 PM CDT	Special Weather Statement	OUN	Washita	46 min
Apr 20, 11:46 PM CDT	Severe Thunderstorm Warning	OUN	Custer, Washita	44 min
Apr 20, 11:53 PM CDT	Special Weather Statement	OUN	Canadian	37 min
Apr 21, 12:00 AM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Kiowa	45 min
Apr 21, 12:08 AM CDT	Severe Thunderstorm Warning	OUN	Cotton, Tillman	53 min
Apr 21, 12:10 AM CDT	Severe Thunderstorm Warning	OUN	Grant	34 min
Apr 21, 12:15 AM CDT	Severe Thunderstorm Warning	OUN	Blaine	45 min
Apr 21, 12:17 AM CDT	Special Weather Statement	OUN	Garfield, Noble	43 min
Apr 21, 12:25 AM CDT	Severe Thunderstorm Warning	OUN	Custer	17 min
Apr 21, 12:27 AM CDT	Severe Thunderstorm Warning	OUN	Canadian, Kingfisher	33 min
Apr 21, 12:36 AM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche	39 min
Apr 21, 1:06 AM CDT	Special Weather Statement	OUN	Logan	24 min
Apr 21, 1:09 AM CDT	Severe Thunderstorm Warning	OUN	Garfield, Kingfisher, Logan, Noble, Payne	28 min
Apr 21, 1:12 AM CDT	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Grady	29 min
Apr 21, 1:13 AM CDT	Special Weather Statement	OUN	Canadian	32 min
Apr 21, 2:12 AM CDT	River Flood Warning	OUN	Pottawatomie, Seminole	24 hr
Apr 21, 2:12 AM CDT	Special Weather Statement	OUN	Oklahoma	33 min
Apr 21, 2:22 AM CDT	Special Weather Statement	OUN	Canadian	23 min
Apr 21, 2:36 AM CDT	Severe Thunderstorm Warning	OUN	Lincoln, Logan, Oklahoma	39 min
Apr 21, 2:50 AM CDT	Special Weather Statement	OUN	Oklahoma	25 min
Apr 21, 3:13 AM CDT	Special Weather Statement	OUN	Lincoln	32 min
Apr 21, 3:15 AM CDT	Special Weather Statement	OUN	Pottawatomie	30 min
Apr 21, 3:30 AM CDT	Special Weather Statement	OUN	Beckham	30 min
Apr 21, 3:32 AM CDT	Special Weather Statement	OUN	Roger Mills	28 min
Apr 21, 3:38 AM CDT	Special Weather Statement	OUN	Lincoln	22 min
Apr 21, 3:47 AM CDT	Severe Thunderstorm Warning	OUN	Beckham, Roger Mills	43 min
Apr 21, 3:49 AM CDT	Severe Thunderstorm Warning	OUN	Custer, Washita	41 min
Apr 21, 3:52 AM CDT	Special Weather Statement	OUN	Seminole	8 min
Apr 21, 4:02 AM CDT	Severe Thunderstorm Warning	OUN	Custer, Washita	43 min
Apr 21, 4:23 AM CDT	Severe Thunderstorm Warning	OUN	Dewey	25 min
Apr 21, 4:27 AM CDT	Severe Thunderstorm Warning	OUN	Custer, Dewey, Roger Mills	24 min
Apr 21, 4:33 AM CDT	Special Weather Statement	OUN	Woods	27 min
Apr 21, 4:38 AM CDT	Special Weather Statement	OUN	Blaine, Caddo	37 min
Apr 21, 4:41 AM CDT	Special Weather Statement	OUN	Custer	34 min
Apr 21, 4:54 AM CDT	Special Weather Statement	OUN	Woods	36 min
Apr 21, 5:03 AM CDT	Special Weather Statement	OUN	Harper	27 min
Apr 21, 5:09 AM CDT	Severe Thunderstorm Warning	OUN	Caddo, Canadian, Grady	37 min
Apr 21, 5:11 AM CDT	Severe Thunderstorm Warning	OUN	Ellis, Harper	49 min
Apr 21, 5:12 AM CDT	Special Weather Statement	OUN	Custer	33 min
Apr 21, 5:24 AM CDT	Special Weather Statement	OUN	Grady	36 min
Apr 21, 5:41 AM CDT	Severe Thunderstorm Warning	OUN	Caddo, Grady	27 min
Apr 21, 5:50 AM CDT	Special Weather Statement	OUN	Canadian	25 min
Apr 21, 5:52 AM CDT	Severe Thunderstorm Warning	OUN	Ellis, Harper, Woodward	38 min
Apr 21, 6:32 AM CDT	Special Weather Statement	OUN	Woodward	28 min
Apr 21, 6:43 AM CDT	Special Weather Statement	OUN	Oklahoma	32 min
Apr 21, 6:53 AM CDT	Severe Thunderstorm Warning	OUN	Canadian, Oklahoma	15 min
Apr 21, 7:16 AM CDT	Special Weather Statement	OUN	Kingfisher	29 min
Apr 21, 7:21 AM CDT	Special Weather Statement	OUN	Oklahoma	24 min
Apr 21, 7:29 AM CDT	Areal Flood Advisory	OUN	Canadian, Kingfisher, Logan, Oklahoma	3 hr
Apr 21, 7:45 AM CDT	Special Weather Statement	OUN	Logan	30 min
Apr 21, 7:47 AM CDT	Special Weather Statement	OUN	Beckham, Custer, Washita	28 min
Apr 21, 7:51 AM CDT	Special Weather Statement	OUN	Cleveland	24 min
Apr 21, 8:05 AM CDT	Flash Flood Warning	OUN	Canadian, Logan, Oklahoma	4 hr
Apr 21, 8:14 AM CDT	Special Weather Statement	OUN	Washita	31 min
Apr 21, 8:15 AM CDT	Special Weather Statement	OUN	Cleveland	30 min
Apr 21, 8:19 AM CDT	Severe Thunderstorm Warning	OUN	Cleveland, McClain	26 min
Apr 21, 8:35 AM CDT	Areal Flood Advisory	OUN	Blaine, Caddo	3 hr
Apr 21, 8:35 AM CDT	Special Weather Statement	OUN	Pottawatomie	25 min
Apr 21, 8:42 AM CDT	Flash Flood Warning	OUN	Canadian, Kingfisher	3 hr
Apr 21, 8:42 AM CDT	Special Weather Statement	OUN	Canadian	33 min
Apr 21, 8:49 AM CDT	Severe Thunderstorm Warning	OUN	Caddo, Canadian, Grady, Kingfisher, Logan, Oklahoma	41 min
Apr 21, 8:57 AM CDT	Special Weather Statement	OUN	Caddo, Comanche, Grady	33 min
Apr 21, 9:04 AM CDT	Special Weather Statement	OUN	Pottawatomie	26 min
Apr 21, 9:16 AM CDT	Severe Thunderstorm Warning	OUN	Caddo, Canadian, Cleveland, Grady, Logan, McClain and 1 more	59 min
Apr 21, 9:31 AM CDT	Special Weather Statement	OUN	Comanche, Cotton, Stephens	44 min
Apr 21, 9:32 AM CDT	Flash Flood Warning	OUN	Lincoln, Logan, Oklahoma	2 hr
Apr 21, 9:42 AM CDT	Severe Thunderstorm Warning	OUN	Cleveland, Garvin, Grady, Lincoln, McClain, Pontotoc and 2 more	63 min
Apr 21, 10:17 AM CDT	Areal Flood Advisory	OUN	Lincoln, Pottawatomie, Seminole	118 min
Apr 21, 10:43 AM CDT	Special Weather Statement	OUN	Hughes, Pontotoc, Seminole	47 min
Apr 21, 11:05 AM CDT	Severe Thunderstorm Warning	OUN	Coal, Hughes, Pontotoc, Seminole	40 min
Apr 21, 12:01 PM CDT	Areal Flood Warning	OUN	Lincoln, Logan, Oklahoma	3 hr
Apr 21, 12:49 PM CDT	Areal Flood Warning	OUN	Blaine, Caddo, Canadian, Kingfisher, Oklahoma	116 min
Apr 21, 12:57 PM CDT	Flash Flood Warning	OUN	Payne	3 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.