Alert archive / Oklahoma / Special Weather Statements in 2021

Special Weather Statement, NWS Norman, OK

April 28, 20214 counties in Oklahoma

NWS Norman, OK issued this special weather statement at Apr 28, 2021, 11:52 PM CDT for 4 counties in Oklahoma. It was in force for 23 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: Apr 28, 2021, 11:52 PM CDT (04:52 UTC)
Expired: Apr 29, 2021, 12:15 AM CDT
In force: 23 min
Issued by: NWS Norman, OK

Counties Coal County, OK, Johnston County, OK, Love County, OK, Marshall County, OK

The radar

The Norman radar (KTLX), 151 km from the middle of the area, began a volume at 04:57 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

Fort Worth, TX (KFWD), launched 00:00Z, 4.9 hours before the alert went out and 133 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: 1526 J/kg
Mixed-layer CIN: -11 J/kg
Mixed-layer LCL: 1058 m above ground
0-6 km bulk shear: 73 kt
0-1 km storm-relative helicity: 191 m²/s²
0-3 km storm-relative helicity: 154 m²/s²
Significant tornado parameter: 2.2
Supercell composite: 9.4

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Apr 28, 6:22 PM CDT, 5 hours 30 minutes earlier.

Area forecast discussion, Apr 28, 6:22 PM CDT, 5 hours 30 minutes before

Area Forecast Discussion
National Weather Service Norman OK
622 PM CDT Wed Apr 28 2021

...New AVIATION...

.UPDATE...
Issued at 1228 PM CDT Wed Apr 28 2021

The convection seen on radar now from near Weatherford up through Watonga
and Enid is associated with convergence along the surface trough. The
convection is shallow, and winds are actually quite weak through 700-mb at
the moment, so they almost have a summer-like appearance in behavior (not
much motion). Mid-level lapse rates are fairly weak and without a decent
amount of surface heating it would be hard for this convection to attain
enough depth to become more organized and much of a concern for severe.
But, a landspout or two cannot be ruled out as vertical vorticity along
the boundary is stretched. Usually, for a more productive landspout day
you would want steeper low level lapse rates, however. Well continue to
monitor trends on this.

Later today, if enough surface based heating can occur, deeper more intense
convection could evolve along this axis, particularly along its southern
flanks into southwest Oklahoma and western north Texas. If this happens,
effective shear would be more than supportive of organized storms including
supercells with mainly a hail/wind threat. But, stronger forcing/cooling
aloft will probably hold mostly west of this surface boundary having limited
influence into the evening. An alternate and probably more likely scenario
is for storms to develop and organized in the Lubbock forecast area closer
to the trough and along the western extent of instability, and then move
into our southwest by late afternoon or evening. The best low-level shear
for a tornado concern should be relegated to the southeast where the
environment is most stable.

Due to recent heavy rains and saturated ground, any additional heavy rain
from the above scenario later today/tonight could be problematic. It wont
take much. Flooding danger is likely the primary life safety concern for
this event.

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 258 PM CDT Wed Apr 28 2021

A very moist atmosphere will support numerous showers and
thunderstorms through tonight. Providing support for convection is
an upper-level low centered over southwest New Mexico. This low
will drift slowly over Chihuahua tonight through Saturday.
Meanwhile, a cold front, located approximately from Ponca City to
Vernon, will pass southeast through the remainder of our forecast
area tonight.

This progression of weather features will result in a continued
risk of heavy rain extending from a few counties behind the front
through the entire area ahead of the front. This heavy rain risk
will end slowly from northwest to southeast, more or less with
the progress of the surface front. Rain chances in general will
diminish as the drier air behind the front moves in. By Thursday
evening, rain chances will be confined to the southern part of
Oklahoma and north Texas.

&&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 258 PM CDT Wed Apr 28 2021

A relatively cool and dry airmass will be in place over most of
Oklahoma and north Texas Thursday night, and a cut-off upper-
level low will still be residing over the Mexican state of
Chihuahua. With the upper low in relatively close proximity, low
rain chances will continue over most of Texas and parts of
southern Oklahoma through Saturday. As the surface airmass shifts
east with time, a return flow of increasing moisture will begin
during the weekend.

Then, the upper-level low will finally start moving northeast into
Texas, before being assimilated into the Westerlies. As the low
approaches north Texas and Oklahoma, rain chances will increase
over eastern and central Oklahoma Saturday night and Sunday.

Early next week, a shortwave trough aloft, combined with an
associated surface low, will maintain rain chances. This time,
the chances will be mainly over northern, then eastern Oklahoma.

CmS
&&

.AVIATION...
(00Z TAFS)
Issued at 617 PM CDT Wed Apr 28 2021

Scattered showers and thunderstorms will occur ahead of, along,
and a moderate distance behind a cold front that extended from
near KSWO to KSPS at 23Z. The front will continue moving southeast
overnight, taking the convection with it. Showers/storms should be
confined almost entirely to southeast Oklahoma after about 06Z. A
layer of moisture at around 1,500 feet will cause some overnight
ceilings, but that should thin and disappear during the day on
Thursday. Some clouds and perhaps showers may linger through the
day near KSPS, but the remainder of the region can expect a few
cumulus clouds, along with mid/high cloudiness, and a north breeze
around 10 kt with somewhat higher gusts.

CmS
&&

.UPPER AIR...
Issued at 1216 PM CDT Wed Apr 28 2021

No upper air flights are currently planned.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  75  57  72  51 /  90  80  10  10
Hobart OK         79  55  72  48 /  80  70  10  10
Wichita Falls TX  78  58  71  52 /  90  80  30  20
Gage OK           73  49  74  44 /  20  30  10   0
Ponca City OK     76  56  74  48 /  70  80  10   0
Durant OK         78  63  74  55 /  80  90  70  30

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch through Thursday morning for OKZ013-019-020-023>032-
     037>048-050>052.

TX...Flood Watch through Thursday morning for TXZ085-086-088>090.

&&

SHORT TERM...23
LONG TERM....23
AVIATION...23

Hazardous weather outlook, Apr 28, 11:52 AM CDT, 12 hours before

Hazardous Weather Outlook
National Weather Service Norman OK
1152 AM CDT Wed Apr 28 2021

OKZ004>048-050>052-TXZ083>090-291700-
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-
1152 AM CDT Wed Apr 28 2021

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

.DAY ONE...Through Tonight...

.Thunderstorms...
Showers and thunderstorms will continue to develop and move across
portions of the area through tonight. Strong to severe storms are
possible, with the highest potential in parts of southern
Oklahoma and western north Texas. Large hail up to the size of
golf balls and wind gusts up to 60 mph are the main concerns.
There is also a low potential for a tornado or two in parts of
south central and southeast Oklahoma later this afternoon and this
evening.

.Heavy Rainfall and Flooding...
Additional heavy rainfall could result in flash flooding across
portions of central and southern Oklahoma and western north Texas
through tonight, especially in those areas that received several
inches of rain overnight last night into this morning.

.SPOTTER AND EMERGENCY MANAGEMENT STATEMENT...
Storm spotter groups and emergency management personnel should
prepare for severe weather operations through tonight.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday...

.Thunderstorms...
Thunderstorms should exit the area Thursday morning. Additional
thunderstorms are possible late Monday into Tuesday of next week.

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

Mahale

In the hours before

Local storm report, Apr 28, 11:24 PM CDT, 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1124 PM CDT WED APR 28 2021

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

0935 PM     TSTM WND DMG     2 N BETHEL ACRES        35.33N 97.05W
04/28/2021                   POTTAWATOMIE       OK   EMERGENCY MNGR

            SIGNIFICANT ROOF DAMAGE AT A HOME AROUND THE
            SHAWNEE TWIN LAKES AREA.

&&

MAHALE

Local storm report, Apr 28, 11:32 PM CDT, 20 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1132 PM CDT WED APR 28 2021

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

1022 PM     HAIL             CENTERVIEW              35.43N 96.67W
04/28/2021  E1.75 INCH       POTTAWATOMIE       OK   BROADCAST MEDIA

&&

MAHALE

Local storm report, Apr 28, 11:36 PM CDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1136 PM CDT WED APR 28 2021

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

0934 PM     TSTM WND DMG     2 W BETHEL ACRES        35.30N 97.09W
04/28/2021                   POTTAWATOMIE       OK   EMERGENCY MNGR

            WINDS BLOWN OUT ON THE WEST SIDE OF A HOUSE.

&&

MAHALE

Local storm report, Apr 28, 11:42 PM CDT, 10 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1142 PM CDT WED APR 28 2021

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

0900 PM     HAIL             2 NNE NORMAN            35.25N 97.42W
04/28/2021  M2.75 INCH       CLEVELAND          OK   NWS EMPLOYEE

            MEASURED 2.77 INCH. WINDOWS AND SKYLIGHTS
            BROKEN.

&&

MAHALE

Local storm report, Apr 28, 11:52 PM CDT, 0 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
1152 PM CDT WED APR 28 2021

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

0857 PM     HAIL             1 NW NORMAN             35.23N 97.45W
04/28/2021  E3.00 INCH       CLEVELAND          OK   TRAINED SPOTTER

&&

MAHALE

Special weather statement, Apr 28, 11:52 PM CDT, 0 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
1152 PM CDT Wed Apr 28 2021

OKZ032-042-043-046>048-050-051-290515-
Love OK-Coal OK-Atoka OK-Carter OK-Johnston OK-Marshall OK-
Pontotoc OK-Hughes OK-
1152 PM CDT Wed Apr 28 2021

...SIGNIFICANT WEATHER ADVISORY FOR Love...Coal...northwestern
Atoka...southeastern Carter...Johnston...Marshall...southeastern
Pontotoc and southeastern Hughes Counties Until 1215 AM CDT...

AT 1151 PM CDT, a strong thunderstorm was located near Clarita,
moving northeast at 55 MPH.

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

LAT...LON 3387 9688 3395 9691 3395 9698 3385 9702
      3385 9709 3382 9705 3378 9709 3379 9720
      3385 9717 3392 9721 3386 9726 3385 9733
      3388 9733 3382 9737 3383 9745 3390 9746
      3493 9609 3468 9609 3468 9590
TIME...MOT...LOC 0451Z 228DEG 49KT 3451 9640

Zwink

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 28, 7:15 PM CDT	Severe Thunderstorm Warning	OUN	Caddo	45 min
Apr 28, 7:55 PM CDT	Severe Thunderstorm Warning	OUN	Caddo, Grady	50 min
Apr 28, 8:28 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, Grady, McClain	47 min
Apr 28, 8:53 PM CDT	Flash Flood Warning	OUN	Cleveland, McClain	3 hr
Apr 28, 8:56 PM CDT	Severe Thunderstorm Warning	OUN	Cleveland, Lincoln, McClain, Oklahoma, Pottawatomie	49 min
Apr 28, 9:13 PM CDT	Areal Flood Advisory	OUN	Cleveland, Grady, McClain, Pottawatomie	3 hr
Apr 28, 9:41 PM CDT	Severe Thunderstorm Warning	OUN	Pottawatomie, Seminole	49 min
Apr 28, 9:45 PM CDT	Special Weather Statement	OUN	Stephens	45 min
Apr 28, 10:23 PM CDT	Special Weather Statement	OUN	Love	37 min
Apr 28, 10:53 PM CDT	Special Weather Statement	OUN	Carter, Hughes, Love, Murray, Pontotoc	37 min
Apr 28, 10:57 PM CDT	Areal Flood Advisory	OUN	Carter, Coal, Hughes, Johnston, Love, Marshall and 2 more	5 hr
Apr 28, 11:19 PM CDT	River Flood Advisory	OUN	Pottawatomie, Seminole	9 hr
Apr 28, 11:24 PM CDT	River Flood Advisory	OUN	Hughes	9 hr
Apr 28, 11:37 PM CDT	Flash Flood Warning	OUN	Carter, Johnston, Love, Marshall, Murray	3 hr
Apr 28, 11:51 PM CDT	River Flood Warning	OUN	Jackson, Kiowa, Tillman	7 hr
Apr 28, 11:52 PM CDT	River Flood Warning	OUN	Atoka	3 days
Apr 28, 11:53 PM CDT	River Flood Advisory	OUN	Cotton	10 hr
Apr 29, 12:06 AM CDT	Areal Flood Advisory	OUN	Atoka, Bryan, Coal, Hughes, Johnston, Marshall	5 hr
Apr 29, 12:23 AM CDT	Special Weather Statement	OUN	Atoka, Bryan	37 min
Apr 29, 6:29 AM CDT	River Flood Advisory	OUN	Bryan	11 hr
Apr 28, 8:20 PM CDT	Special Weather Statement	OUN	Baylor	25 min
Apr 28, 9:04 PM CDT	Special Weather Statement	OUN	Clay	26 min
Apr 28, 9:48 PM CDT	Special Weather Statement	OUN	Clay	27 min

Nearby

Special Weather Statements in Oklahoma, 2021 Every special weather statement in 2021

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.