Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 496, NWS Norman, OK

August 7, 2018Lincoln County, Pottawatomie County, Seminole County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Aug 7, 2018, 5:23 PM CDT for Lincoln County, Pottawatomie County, Seminole County, Oklahoma. It was in force for 40 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
Aug 7, 2018, 5:23 PM CDT (22:23 UTC)
Expired
Aug 7, 2018, 6:03 PM CDT
In force
40 min
Issued by
NWS Norman, OK
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Lincoln County, OK, Pottawatomie County, OK, Seminole County, OK

The radar

The Norman radar (KTLX), 42 km from the middle of the area, began a volume at 22:26 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 nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 10.4 hours before the alert went out and 55 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, Norman, OK at 12:00Z on 2018-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1027 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Norman, OK at 12:00Z on 2018-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 24 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
1027 J/kg
Mixed-layer CIN
-107 J/kg
Mixed-layer LCL
1442 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
24 m²/s²
0-3 km storm-relative helicity
168 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.1

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 Aug 7, 3:06 PM CDT, 2 hours 17 minutes earlier.

Area forecast discussion, Aug 7, 3:06 PM CDT, 2 hours 17 minutes before
Area Forecast Discussion
National Weather Service Norman OK
306 PM CDT Tue Aug 7 2018

.DISCUSSION...
Latest surface observations show a quasi-stationary front Cheyenne
to near Guthrie to near Cushing. The environment near this
boundary has become moderately unstable with MLCAPE 1,500-2,000
J/kg, due to diabatic heating of a comparatively more moist
boundary layer than has been seen the last few days. Isolated to
scattered convection has formed near this boundary. Effective
shear is marginally supportive of sustained updrafts and perhaps a
marginally severe wind/hail threat with the strongest storms into
early evening, especially given DCAPE up to 1,200 J/kg suggesting
brief strong/severe microbursts are possible with the most intense
storms.

Later tonight, modest strengthening of low-level jet orthogonal
to aforementioned boundary should support an increase in
convection. Furthermore, remnant MCS may move along and north of
the synoptic surface boundary as well. The greatest coverage
should be after midnight across northwest/north-central Oklahoma
spreading into portions of central Oklahoma late tonight and
eventually southeast portions of our area tomorrow morning.
Convection could linger into the afternoon across southern
portions of the area, and by evening/overnight will increase in
coverage again as another shortwave trough approaches. Some of
this is conditional on placement of synoptic boundary which will
likely be augmented by convective outflow. Additionally, there is
concern for locally heavy rainfall amounts given the anomalous
moisture (PWAT on average around ~1.75" in models) and weak
850-300 hPa flow. Any flooding/flash flooding concerns should be
localized as it appears now across mainly southern Oklahoma.

Showers and storms should decrease Thur-Fri but could linger near
the Red River, but most of the area will be dry and cooler than
has been seen the last several days. A closed low and return of
deeper moisture could bring an increase in convective coverage
late this weekend into early next week. Little/no change was made
to this portion of the forecast.

BRB

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  71  83  69  88 /  80  70  50  10
Hobart OK         75  87  70  90 /  50  40  60  20
Wichita Falls TX  78  92  72  90 /  40  30  70  30
Gage OK           70  86  65  90 /  80  30  30  10
Ponca City OK     73  88  68  91 /  50  50  20  10
Durant OK         75  90  72  88 /  40  60  70  40

&&

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

09/12
Hazardous weather outlook, Aug 7, 3:18 PM CDT, 2 hours 5 minutes before
Hazardous Weather Outlook...UPDATED
National Weather Service Norman OK
318 PM CDT Tue Aug 7 2018

OKZ004>048-050>052-TXZ083>090-082030-
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-
318 PM CDT Tue Aug 7 2018

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

.DAY ONE...Through Tonight...

.Thunderstorms...
This afternoon and evening, thunderstorms will be possible, mainly
across central and eastern Oklahoma, including the Oklahoma City
area. Additional thunderstorms are possible across much of the
area late tonight. A few storms could be strong to severe with the
primary hazard being damaging wind gusts to 60 mph.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday...

.Thunderstorms...
Thunderstorms will be possible across most of the area Wednesday
and Thursday. The highest chances for thunderstorms are expected
early Wednesday morning, and late Wednesday night into early
Thursday morning. A few strong to severe storms will be possible
Wednesday across southwest Oklahoma and portions of western north
Texas, with a threat of damaging wind gusts.

At least a low chance for thunderstorms will continue through
Sunday, especially across the southern half of Oklahoma and
adjacent parts of north Texas.

.Heavy Rainfall...
Heavy rainfall will be possible across the northern two-thirds of
Oklahoma Wednesday morning, and then again Wednesday night into
early Thursday morning across the southern two thirds of
Oklahoma. Excessive rainfall may lead to localized flooding.

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, Aug 7, 3:58 PM CDT, 1 hour 25 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
358 PM CDT TUE AUG 7 2018

OKZ024-025-072130-
Oklahoma OK-Canadian OK-
358 PM CDT TUE AUG 7 2018

...SIGNIFICANT WEATHER ADVISORY FOR southwestern Oklahoma and east
central Canadian Counties Until 430 PM CDT....

AT 357 PM CDT, a strong thunderstorm was located over western
Oklahoma City, moving east at 15 MPH.

HAZARDS INCLUDE...
Wind gusts to 40 MPH...

Locations impacted include...
West Oklahoma City, Yukon, Mustang, Wiley Post Airport, and Will
Rogers Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3557 9746 3538 9755 3538 9770 3545 9783
      3562 9775
TIME...MOT...LOC 2057Z 290DEG 11KT 3551 9770

BRB
Special weather statement, Aug 7, 4:14 PM CDT, 1 hour 9 minutes before
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Local storm report, Aug 7, 4:28 PM CDT, 55 minutes before
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Special weather statement, Aug 7, 4:28 PM CDT, 55 minutes before
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Special weather statement, Aug 7, 4:44 PM CDT, 39 minutes before
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Special weather statement, Aug 7, 5:12 PM CDT, 11 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 7, 2:42 PM CDTSpecial Weather StatementOUNLincoln, Oklahoma48 min
Aug 7, 3:28 PM CDTSevere Thunderstorm WarningOUNLincoln47 min
Aug 7, 3:31 PM CDTSpecial Weather StatementOUNCanadian, Oklahoma29 min
Aug 7, 3:58 PM CDTSpecial Weather StatementOUNOklahoma32 min
Aug 7, 4:14 PM CDTSpecial Weather StatementOUNLincoln31 min
Aug 7, 4:28 PM CDTSpecial Weather StatementOUNPottawatomie32 min
Aug 7, 4:44 PM CDTSpecial Weather StatementOUNLincoln31 min
Aug 7, 5:12 PM CDTSpecial Weather StatementOUNLincoln33 min
Aug 7, 5:27 PM CDTSpecial Weather StatementOUNPottawatomie18 min
Aug 7, 5:47 PM CDTSpecial Weather StatementOUNPottawatomie28 min
Aug 7, 6:05 PM CDTSpecial Weather StatementOUNSeminole25 min
Aug 7, 6:10 PM CDTSpecial Weather StatementOUNPottawatomie20 min
Aug 7, 6:22 PM CDTSpecial Weather StatementOUNCleveland23 min
Aug 7, 6:28 PM CDTSpecial Weather StatementOUNPottawatomie32 min
Aug 7, 6:51 PM CDTSpecial Weather StatementOUNCleveland24 min

Nearby

Severe Thunderstorm Warnings in Oklahoma, 2018Every severe thunderstorm warning in 2018

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.