Alert archive / Oklahoma / Special Weather Statements in 2021

Special Weather Statement, NWS Norman, OK

July 31, 2021Grant County, Oklahoma

NWS Norman, OK issued this special weather statement at Jul 31, 2021, 9:18 PM CDT for Grant County, Oklahoma. It was in force for 27 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
Jul 31, 2021, 9:18 PM CDT (02:18 UTC)
Expired
Jul 31, 2021, 9:45 PM CDT
In force
27 min
Issued by
NWS Norman, OK

County Grant County, OK

The radar

The Vance AFB radar (KVNX), 51 km from the middle of the area, began a volume at 02:18 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 00:00Z, 2.3 hours before the alert went out and 189 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 00:00Z on 2021-08-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1977 joules per kilogram.LCLEL10008507005003002001001 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 00:00Z on 2021-08-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 28 square meters per square second.1939Sfc1 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
1977 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
1902 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
28 m²/s²
0-3 km storm-relative helicity
17 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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 Jul 31, 6:15 PM CDT, 3 hours 3 minutes earlier.

Area forecast discussion, Jul 31, 6:15 PM CDT, 3 hours 3 minutes before
Area Forecast Discussion
National Weather Service Norman OK
615 PM CDT Sat Jul 31 2021

...New AVIATION, UPPER AIR...

.SHORT TERM...
(This evening through Sunday)
Issued at 309 PM CDT Sat Jul 31 2021

Outflow from last nights convection across northern Kansas
currently becoming nearly stationary across far southern Kansas.
Primary cold front progd to move southward across Kansas this
afternoon and continue to move into northern Oklahoma early this
evening. While most organized area of convection is expected to be
where these boundaries meet over southern Kansas, pre-frontal and
highly elevated storms are developing from the Texas Panhandle
eastward into northern portions of Oklahoma in deeply mixed,
veered flow. While this initial storm activity may be more or less
scattered due to lack of strong forcing along mentioned
boundaries, increased storm coverage expected through the evening
as outflow will help enhance low level convergence. Moderate mixed
layer CAPE and deep layer shear progd to increase toward 20 KT
should allow a few organized and persistent storms this evening to
yield damaging wind gusts across northern portions of Oklahoma.
By the overnight hours, aided by anticipated cold pool
development, showers and storms should begin to spread southward
into southwest and central portions of Oklahoma, although less
organized. Highest chances for rain will be retained across
northern and western portions of Oklahoma through the night.

Remnant, elevated shower activity with a few embedded storms
possible through Sunday morning across southwest Oklahoma/western
north Texas up into central Oklahoma. As instability increases
through the afternoon and early evening across the Red River
Valley of southern Oklahoma/northern Texas, redevelopment of
organized strong storms appears likely. During this time,
precipitable water values progd to exceed 2 inches, and with slow
storm movement, high rain totals and damaging wind gusts will be
possible across far southern Oklahoma and northern Texas into
Sunday night.

Temperatures on Sunday, for at least the northern two-thirds of
Oklahoma and portions of western north Texas, will be 15 to 20
degrees cooler than those seen this afternoon. However, ahead of
the front across far southeast Oklahoma, hot and humid conditions
are expected Sunday afternoon, which will yield extension of the
heat advisory over that area.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 309 PM CDT Sat Jul 31 2021

In the system's wake, northerly flow aloft is expected through
much of the week across the Southern Plains. North to northeast
surface winds will advect lower temperatures and dewpoints. As a
result, the weather will be noticeably more comfortable (at least
for early August standards) through mid week with lower humidity
and slightly below-average temperatures.

Temperatures will begin to increase toward the latter half of the
week as mid-level heights rise and a thermal ridge develops to
the west (the Southern Plains will be eastern periphery of the
thermal ridge).

The chance for convection appears quite low through much of the
extended period. While a subtle wave embedded in the
northerly/northwesterly flow could bring in remnant convection or
enhance the ascent, there is limited signal in the deterministic
guidance. The NBM 90th percentile QPF values are very low, which
indicates ensemble guidance is relatively dry as well.

Mahale

&&

.AVIATION...
(00Z TAFS)
Issued at 615 PM CDT Sat Jul 31 2021

Scattered showers and thunderstorms have developed across northern
Oklahoma ahead of a cold front moving through Kansas. The storm
chances and the cold front will both spread south this evening and
into Sunday. VFR conditions are expected in general, with some
areas of MVFR and localized IFR, mainly in and near the showers
and thunderstorms.

&&

.UPPER AIR...
Issued at 615 PM CDT Sat Jul 31 2021

A 00Z upper air flight has been released. Otherwise, no other
upper air flights are planned at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  73  86  67  87 /  40  40  10   0
Hobart OK         73  87  65  89 /  40  40  20   0
Wichita Falls TX  77  93  69  90 /  10  50  50  10
Gage OK           68  83  63  88 /  70  50  10   0
Ponca City OK     71  87  62  86 /  70  30   0   0
Durant OK         77  96  71  91 /   0  50  60  20

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Heat Advisory until 9 PM CDT this evening for OKZ006>008-011>013-
     018>020-024>032-039>048-050>052.

     Heat Advisory from noon to 7 PM CDT Sunday for OKZ048-052.

TX...Heat Advisory until 9 PM CDT this evening for TXZ086-089-090.

&&

SHORT TERM...11
LONG TERM....10
AVIATION...26
Hazardous weather outlook, Jul 31, 11:31 AM CDT, 9 hours 47 minutes before
Hazardous Weather Outlook...UPDATED
National Weather Service Norman OK
1131 AM CDT Sat Jul 31 2021

OKZ004>048-050>052-TXZ083>090-011645-
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-
1131 AM CDT Sat Jul 31 2021

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

.DAY ONE...Today and Tonight...

.Heat...
Hot and humid conditions will continue this afternoon with heat
index values of 102 to 110 degrees.

.Thunderstorms...
Thunderstorm chances will return to the region this evening and
tonight. There is a marginal risk for severe storms across
northern Oklahoma. Damaging winds will be the main threat.

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

.Thunderstorms...
Thunderstorm chances will continue Sunday and Sunday night in
association with a cold front. Some storms may produce strong wind
gusts and heavy rain. Storms may linger around southern Oklahoma
and north Texas into Monday morning.

Low chances for scattered thunderstorms will return Wednesday and
Thursday.

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, Jul 31, 8:04 PM CDT, 1 hour 14 minutes before
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Special weather statement, Jul 31, 8:45 PM CDT, 33 minutes before
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Special weather statement, Jul 31, 8:56 PM CDT, 22 minutes before
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Special weather statement, Jul 31, 9:07 PM CDT, 11 minutes before
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Special weather statement, Jul 31, 9:14 PM CDT, 4 minutes before
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Special weather statement, Jul 31, 9:18 PM CDT, 0 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 7:37 PM CDTSpecial Weather StatementOUNAlfalfa38 min
Jul 31, 7:42 PM CDTSpecial Weather StatementOUNWoods18 min
Jul 31, 7:45 PM CDTSpecial Weather StatementOUNAlfalfa30 min
Jul 31, 7:54 PM CDTSpecial Weather StatementOUNHarper36 min
Jul 31, 8:04 PM CDTSpecial Weather StatementOUNAlfalfa26 min
Jul 31, 8:45 PM CDTSpecial Weather StatementOUNWoodward30 min
Jul 31, 8:56 PM CDTSpecial Weather StatementOUNHarper34 min
Jul 31, 9:14 PM CDTSpecial Weather StatementOUNHarper31 min
Jul 31, 9:24 PM CDTSpecial Weather StatementOUNKay21 min
Jul 31, 9:27 PM CDTSpecial Weather StatementOUNHarper18 min
Jul 31, 9:31 PM CDTSpecial Weather StatementOUNWoodward29 min
Jul 31, 9:46 PM CDTSpecial Weather StatementOUNKay29 min
Jul 31, 10:26 PM CDTSpecial Weather StatementOUNKay34 min
Jul 31, 10:30 PM CDTSpecial Weather StatementOUNGrant30 min
Jul 31, 10:49 PM CDTAreal Flood AdvisoryOUNWoods3 hr
Jul 31, 11:03 PM CDTSpecial Weather StatementOUNGrant27 min
Jul 31, 11:29 PM CDTAreal Flood AdvisoryOUNKay3 hr
Jul 31, 11:49 PM CDTSpecial Weather StatementOUNNoble41 min
Jul 31, 11:59 PM CDTAreal Flood AdvisoryOUNEllis, Harper3 hr
Aug 1, 12:05 AM CDTFlash Flood WarningOUNKay3 hr
Aug 1, 12:36 AM CDTSpecial Weather StatementOUNNoble, Payne39 min
Aug 1, 2:25 AM CDTAreal Flood AdvisoryOUNGarfield3 hr
Aug 1, 2:28 AM CDTSpecial Weather StatementOUNLogan47 min
Aug 1, 4:18 AM CDTSpecial Weather StatementOUNCanadian42 min

Nearby

Special Weather Statements in Oklahoma, 2021Every 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.