Special Weather Statement, NWS Tulsa, OK

Area Forecast Discussion
National Weather Service Tulsa OK
858 PM CDT Thu Jul 15 2021

...UPDATE...

.DISCUSSION...
Isolated storms that popped up within a pocket of instability
north of Fort Smith are slowly running out of instability and
should continue to weaken and dissipate. Storms are becoming more
numerous along the outflow boundary across southern KS and should
get additional upper level support through the remainder of the
evening into the early morning hours as a shortwave over central
KS continues to dig southeast. The latest CAM guidance continues
to support the idea of the outflow boundary drifting south with
additional storms developing westward across north-central OK and
eventually moving east into our northern tier counties. Gridded
data was updated earlier to reflect a slightly later onset of
convection and hold POPs higher west of I-44 through sunrise then
shift them south and east through late Friday morning.

Deep moisture continues to be pooled along the outflow boundary
and ahead of the stationary front from northwest OK into northern
KS with strong 850-700 moisture transport across much of central
and northeast Oklahoma. As a result storms should remain very
efficient in producing very heavy rainfall rates in excess of
2"/hour. With marginal deep layer shear also in place and flow
generally parallel to the sagging outflow boundary, localized
flash flooding will remain a concern overnight. Sufficient cold
pool strength should be achieved by daybreak to help push the
outflow south as convection begins to increase across northwest AR
and east-central OK. Will need to watch for redevelopment in the
wake of the morning round of storms but with uncertainty in that
and the eventual outflow location do not anticipate expanding the
Flash Flood watch at this time.

&&

.PREV DISCUSSION... /Issued 627 PM CDT Thu Jul 15 2021/

AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Current VFR conditions will likely give way to MVFR to IFR
conditions later tonight across northeast Oklahoma and
far northwest Arkansas as showers and storms roll into
the area. MVFR to VFR conditions are expected Friday at
most sites with showers and storms still affecting area
sites at least through the morning hours.

PREV DISCUSSION... /Issued 206 PM CDT Thu Jul 15 2021/

DISCUSSION...
Persistent pre-frontal convection across northern OK into
southeast KS is expected to expand in coverage and eventually sag
into portions of northeast OK this evening. Instability (SBCAPES
around 3000 J/KG) will be sufficient for some strong/marginally
severe storms, although overall weak shear should prevent more
significant severe activity from occurring. With PWATS running
around 2", expect very efficient rainfall rates, with some locally
heavy rainfall likely. Used the HREF mean QPF which focuses the
heaviest rainfall from southeast KS into northeast OK, although
there remains some uncertainty as to where the heaviest rain may
occur. That said, went ahead with a Flash Flood Watch overnight
for parts of northeast OK.

Bulk of the CAMs shift the showers/storms farther southeast on
Friday. There is some concern for additional development closer to
the frontal boundary by Friday night as suggested by the
NAM/ECMWF, so will need to monitor for the threat of additional
heavy rainfall.

Rain chances will continue into the weekend, with an uptick in
activity possible by early next week as another wave and
associated front dip into the region. The better chances of rain
are expected to shift farther south Tuesday into Wednesday as the
boundary sags south.

Temperatures will remain below normal through the period, with
highs generally in the 80s for early/mid week. Expected a gradual
warming trend late in the week as drier conditions prevail.

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Flash Flood Watch through Friday morning for OKZ054>059-061>063.

AR...None.
&&

SHORT TERM...24

Hazardous Weather Outlook
National Weather Service Tulsa OK
1056 PM CDT Thu Jul 15 2021

ARZ001-002-010-011-019-020-029-OKZ049-053>076-161015-
Adair OK-Benton AR-Carroll AR-Cherokee OK-Choctaw OK-Craig OK-
Crawford AR-Creek OK-Delaware OK-Franklin AR-Haskell OK-Latimer OK-
Le Flore OK-Madison AR-Mayes OK-McIntosh OK-Muskogee OK-Nowata OK-
Okfuskee OK-Okmulgee OK-Osage OK-Ottawa OK-Pawnee OK-Pittsburg OK-
Pushmataha OK-Rogers OK-Sebastian AR-Sequoyah OK-Tulsa OK-Wagoner OK-
Washington OK-Washington AR-
1056 PM CDT Thu Jul 15 2021

This Outlook is for Northwest and West Central Arkansas as well as
much of Eastern Oklahoma.

.DAY ONE...Today and Tonight.

SEVERE THUNDERSTORM.
	RISK...Limited.
	AREA...North of Interstate 44.
	ONSET...Overnight.

FLASH FLOOD.
	RISK...Limited.
	AREA...Far Northeast Oklahoma.
	ONSET..Overnight.

HEAVY RAIN.
	RISK...Elevated.
	AREA...Along and North of Highway 412 in Northeast Oklahoma.
	ONSET...Overnight.

DISCUSSION...
Showers and thunderstorms will become more numerous overnight
along an outflow boundary stretching across south-central and
southeast Kansas. This area of activity will move slowly south
and east with time across northeast Oklahoma and eventually
northwest Arkansas by mid-morning Friday. Unseasonably high
moisture values in place across far northern Oklahoma will allow
for efficient rain-producing storms with very high rainfall
rates. The combination of slow storm motion and activity repeating
over the same area will lead to localized flash flooding
potential overnight tonight, especially near the Kansas border.
The threat of severe weather will otherwise remain low overnight,
however, if the storms do form into a larger complex, a damaging
wind threat may emerge.

SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT...
Local Spotter Activation May Be Needed.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.
FRIDAY...Thunderstorm Potential...Heavy Rain Potential.
SATURDAY AND SUNDAY...Thunderstorm Potential.
MONDAY...Thunderstorm Potential...Heavy Rain Potential.
TUESDAY AND WEDNESDAY...Thunderstorm Potential.

EXTENDED DISCUSSION...
Unsettled weather will remain across the area through the weekend
with multiple rounds of showers and thunderstorms expected. The
overall severe weather risk will remain low, however, a few
strong to severe storms will be possible mainly during the late
afternoon and evening. The greater concern is for pockets of
heavy rainfall to occur. There is really no one particular day
through the weekend when heavy rainfall looks more likely however
the focus for thunderstorms will gradually shift south late Monday
into Tuesday. This pattern change will bringing decreasing rain
chances across areas that experienced earlier heavy rains.
weather.gov/tulsa contains additional information.

Special Weather Statement
National Weather Service Tulsa OK
1246 AM CDT Fri Jul 16 2021

OKZ054>057-061-160630-
Craig OK-Osage OK-Rogers OK-Nowata OK-Washington OK-
1246 AM CDT Fri Jul 16 2021

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL CRAIG...NORTHWESTERN
ROGERS...NORTHEASTERN OSAGE...WASHINGTON AND NOWATA COUNTIES UNTIL
130 AM CDT...

At 1245 AM CDT, strong thunderstorms were located along a line
extending from near Dearing to 3 miles north of Wann to 5 miles east
of Bigheart to 8 miles northwest of Sunset Lake to 3 miles northeast
of Foraker. Movement was southeast at 35 mph.

Wind gusts up to 50 mph as well as small hail up to one half inch in
diameter will be possible with these storms. Very heavy rainfall is
occurring with these thunderstorms as well.

Locations in or near the path include...
Bartlesville...                   Nowata...
Pawhuska...                       Dewey...
Barnsdall...                      South Coffeyville...
Copan...                          Ramona...
Ochelata...                       Delaware...
Lenapah...                        Wann...
Elgin...                          Grainola...
Foraker...                        Bigheart...
Bartlesville Municipal Airport... Osage Hills State Park...
Watova...                         Pearsonia...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3700 9551 3685 9533 3661 9558 3652 9588
      3652 9608 3660 9655 3700 9671
TIME...MOT...LOC 0545Z 330DEG 31KT 3706 9573 3697 9582 3687 9613 3688
9633 3691 9652

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