Severe Thunderstorm Warning 656, NWS Norman, OK

Area Forecast Discussion
National Weather Service Norman OK
247 PM CDT Sun Aug 16 2020

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This evening through Monday)
Issued at 247 PM CDT Sun Aug 16 2020

There are three ongoing mechanisms for convection across the area
this afternoon. Convection is ongoing and developing along and
north of an outflow boundary across central into northwest
Oklahoma. The radar mosaic suggests an MCV north of the outflow
boundary, which may explain why convection is occuring well behind
the outflow boundary (i.e., another source of ascent).

This outflow boundary is merging with a remnant (somewhat
diffuse) boundary across south central Oklahoma (especially on the
western flank of the old boundary where northeasterly winds are
gustier). Additional showers and thunderstorms are developing
along this remnant boundary across southeast Oklahoma. Finally,
upslope flow across the High Plains is resulting in convection in
the Texas panhandle. These areas of convection will continue
through the evening hours (with a slow south and eastward
progression).

While effective bulk shear is marginal, moderate to high
instability (MLCAPE ~4000-4500 J/kg) will favor pulse-type severe
thunderstorms that could produce marginally severe hail and
downbursts (i.e., damaging wind gusts) with the most intense
cores. If storms can coalesce and develop any substantial cold
pools, that would also increase the potential for damaging wind
gusts.

Mahale

&&

.LONG TERM...
(Monday night through next Saturday)
Issued at 247 PM CDT Sun Aug 16 2020

Through the extended forecast, a highly-amplified mid-level ridge
will remain across the western United States (centered near the
Four Corners region). As a result, the hottest temperatures will
remain to the west of the Southern Plains. Temperatures will be
slightly cooler/less hot and dew points slightly lower than recent
days.

Northerly flow aloft across the Southern Plains may result in
occasional complexes of thunderstorms to approach at least
Northern Oklahoma (around the eastern periphery of the ridge).
Therefore, low probabilities were included for many of the
overnight/early morning hours across northwest/northern Oklahoma.
The highest probabilities for convection would be when embedded
shortwave troughs approach from the north (enhancing the effective
bulk shear), but predictability/timing on these waves is
uncertain. Nevertheless, most of the period should be dry with
seasonable temperatures.

Mahale

&&

.AVIATION...
(18Z TAFS)
Issued at 1245 PM CDT Sun Aug 16 2020

Widely scattered thunderstorms across northern Oklahoma
continue to build slowly southward. Through 20-21Z WWR/OKC
appear to have the best opportunity of being impacted by
thunderstorms with MVFR conditions (mainly visibility). By mid
to late afternoon, other storms may develop along a surface
boundary in southern Oklahoma.  Models suggest most storms
will remain away from most TAF sites. This evening and overnight,
mainly VFR conditions are anticipated with a chance to slight
chance of storms.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  70  91  68  89 /  10  10   0   0
Hobart OK         69  94  68  93 /  20  10   0   0
Wichita Falls TX  71  93  71  94 /  30  20  10   0
Gage OK           66  92  64  92 /  30  10   0   0
Ponca City OK     67  91  66  88 /  10  10   0   0
Durant OK         72  94  71  95 /  30  10   0   0

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Heat Advisory until 7 PM CDT this evening for OKZ031-032-039>043-
     045>048-050>052.

TX...None.
&&

SHORT TERM...10
LONG TERM....10
AVIATION...06

Hazardous Weather Outlook
National Weather Service Norman OK
1212 PM CDT Sun Aug 16 2020

OKZ004>048-050>052-TXZ083>090-171715-
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-
1212 PM CDT Sun Aug 16 2020

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

.DAY ONE...Through Tonight...

.Heat...
Heat index values of 105 to 110 are expected in southern Oklahoma
and western north Texas this afternoon.

.Thunderstorms...
An area of thunderstorms will continue to progress southeastward
across northwestern and north central Oklahoma through lunchtime.
Hail up to the size of nickels and wind gusts exceeding 50 mph
will be possible with the strongest storms.

Later this afternoon through tonight, thunderstorms will redevelop
over southwestern and southern Oklahoma, and north Texas. A few
of these storms may become severe, with a threat of hail up to the
size of quarters and wind gusts exceeding 60 mph.

.DAYS TWO THROUGH SEVEN...Monday through Saturday...

.Thunderstorms...
Scattered thunderstorms will continue over western and
southwestern Oklahoma, and north Texas into Monday morning. A few
strong storms will be possible.

Low thunderstorm chances return to northwestern and western
Oklahoma late Tuesday night through early Wednesday morning, and
again late Thursday night through early Friday morning.

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
224 PM CDT Sun Aug 16 2020

OKZ028-162015-
McClain OK-
224 PM CDT Sun Aug 16 2020

...SIGNIFICANT WEATHER ADVISORY FOR southwestern McClain County Until
315 PM CDT...

AT 222 PM CDT, a strong thunderstorm was located near Washington,
moving southeast at 10 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts to 50 MPH...
Heavy rain can lead to reduced visibility...
Frequent cloud to ground lightning...

Locations impacted include...
Blanchard, Purcell, Goldsby, Dibble, Washington, Cole and Criner.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3497 9735 3493 9741 3500 9767 3515 9767
      3511 9740 3509 9740 3508 9739 3509 9738
      3508 9736 3506 9735 3503 9736 3499 9734
TIME...MOT...LOC 1922Z 304DEG 9KT 3507 9750

03

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
243 PM CDT Sun Aug 16 2020

OKZ028>030-162030-
Pottawatomie OK-Cleveland OK-McClain OK-
243 PM CDT Sun Aug 16 2020

...SIGNIFICANT WEATHER ADVISORY FOR southwestern Pottawatomie...
southeastern Cleveland and south central McClain Counties Until 330
PM CDT...

AT 241 PM CDT, a strong thunderstorm was located 4 miles northeast of
Wayne, moving southeast at 15 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts to 50 MPH...
Heavy rain can lead to reduced visibility...
Frequent cloud to ground lightning...

Locations impacted include...
Purcell, Lexington, Wayne, Byars and Rosedale.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3486 9699 3485 9732 3501 9738 3505 9723
      3498 9713
TIME...MOT...LOC 1941Z 326DEG 11KT 3496 9727

03

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
249 PM CDT Sun Aug 16 2020

OKZ028-040-162030-
Garvin OK-McClain OK-
249 PM CDT Sun Aug 16 2020

...SIGNIFICANT WEATHER ADVISORY FOR northwestern Garvin and
southwestern McClain Counties Until 330 PM CDT...

AT 245 PM CDT, a strong thunderstorm was located near Criner, moving
southeast at 20 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts to 50 MPH...
Heavy rain can lead to reduced visibility...
Frequent cloud to ground lightning...

Locations impacted include...
Lindsay, Maysville, Criner and Payne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3495 9767 3504 9750 3484 9729 3472 9755
TIME...MOT...LOC 1945Z 327DEG 16KT 3493 9755

03

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE Norman OK
302 PM CDT Sun Aug 16 2020

OKZ009-014-162100-
Roger Mills OK-Ellis OK-
302 PM CDT Sun Aug 16 2020

...SIGNIFICANT WEATHER ADVISORY FOR northern Roger Mills and southern
Ellis Counties Until 400 PM CDT...

AT 259 PM CDT, strong thunderstorms were along a line extending from
4 miles southeast of Higgins to 12 miles north of Roll, moving
southeast at 25 MPH.

HAZARDS INCLUDE...
Hail up to the size of nickels...
Wind gusts over 50 MPH...
Heavy rain can lead to reduced visibility...
Frequent cloud to ground lightning...

Locations impacted include...
Crawford and Angora.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3614 10000 3603 9948 3574 9942 3587 10000
TIME...MOT...LOC 1959Z 315DEG 21KT 3606 9999 3596 9964

03

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