Flash Flood Watch 11, NWS Tulsa, OK

Area Forecast Discussion
National Weather Service Tulsa OK
1250 PM CDT Mon Aug 31 2020

.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
Scattered showers and thunderstorms will remain possible across
the CWA this afternoon with scattered to broken mid and high
clouds forecast. This evening and overnight tonight...additional
convection is forecast to develop and move across the CWA and
remain possible into the morning hours Tuesday. Within the
stronger convection...periods of MVFR and heavy rain will be
possible. By late tonight through Tuesday morning...IFR/MVFR
conditions are forecast to become common over the CWA with rain
showers and VCTS remaining possible through the end of the TAF
period over Southeast Oklahoma into Northwest Arkansas. Winds
through the period look to be variable within the convection
otherwise...much of the region should remain southerly through the
period. A surface frontal boundary looks to stall over far
Northeast Oklahoma which could allow for more northerly winds for
KBVO tonight.

&&

.PREV DISCUSSION... /Issued 1057 AM CDT Mon Aug 31 2020/

..UPDATE...

DISCUSSION...
Several factors remain in play for the rest of today with regards
to precip potentials and afternoon temps across Eastern Oklahoma
and Northwest Arkansas. At mid morning...a 30-35KT low level jet
streak continued across Eastern Oklahoma over an area of low/mid
level warm advection combined within an area of deeper moisture.
In response...continued development of showers and thunderstorms
were ongoing across much of the CWA...moving from west to east.
This activity was ahead of a surface frontal boundary positioned
from Northwest Oklahoma through Eastern Kansas and into Northwest
Missouri...slowly sagging southeast toward the CWA. And...finally
a secondary boundary associated with an ongoing MCS over Western
Missouri was pushing south southeast toward Northwest Arkansas.

Through this afternoon...the low level jet streak is expected to
weaken...though continued warm advection combined with the deeper
moisture should allow for shower and thunderstorm chances to be
possible over the region. The greater potentials look to be over
East Central into Southeast Oklahoma as well as West Central
Arkansas. Additional showers and thunderstorms may also be
possible for far Northwest Arkansas in response to the approaching
MCS...though the majority of which should remain east/northeast
of the CWA. Finally...the surface frontal boundary is forecast to
reach Osage county in Northeast Oklahoma late afternoon and become
nearly stationary over Northeast Oklahoma this evening. This will
allow for another round of thunderstorms to develop and spread
across the CWA late afternoon/this evening.

Severe potentials will remain possible with the possible
interactions of multiple boundaries combined with dewpoints in the
70s over the region. These potentials look to be somewhat depending
on how far south the MCS boundary can set up and the frontal
boundary can set up over the CWA. However...damaging wind...large
hail and also a low tornado potential will remain possible with
the greater potentials with the late afternoon/evening convection.
Also possible will be locally heavy rainfall and an increase in
flash flood conditions...especially over locations that see
training storms through this afternoon and with the additional
convection forecast this evening/tonight.

With the ongoing precip and additional development forecast
through this afternoon...afternoon temps look to vary from 80s
under convection to 90s where clouds can break. At this time parts
of Northeast Oklahoma...west of Highway 75 and also far Southeast
Oklahoma may have the greater chances of reaching into the 90s
while...while Northwest Arkansas look to have the greater chance
for staying in the 80s. Moisture pooling along the approaching
surface frontal boundary combining with overall dewpoints in the
70s will aid in heat index values in the 100 to near 105 degree
range for the warmer locations. There may be a brief period where
advisory criteria can be reached though not expecting an advisory
to be issued at this time.

For the morning update...have adjusted hourly
pops/wx/temp/dewpoint grids for this afternoon based on the
mentioned above and latest trends/ingested observations. Will
continue to monitor conditions closely for additional updates.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   92  73  85  71 /  40  70  60  50
FSM   90  73  81  73 /  70  80  80  50
MLC   91  71  80  70 /  60  90  90  70
BVO   91  70  85  69 /  30  80  60  50
FYV   87  69  80  68 /  70  80  80  50
BYV   89  71  82  69 /  70  70  80  50
MKO   88  72  80  70 /  70  80  70  50
MIO   88  71  82  69 /  60  80  60  50
F10   90  71  80  69 /  70  80  70  60
HHW   92  74  83  72 /  50  80  90  80

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&

AVIATION.....20

Hazardous Weather Outlook
National Weather Service Tulsa OK
136 PM CDT Mon Aug 31 2020

ARZ001-002-010-011-019-020-029-OKZ049-053>076-011030-
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-
136 PM CDT Mon Aug 31 2020

...SEVERE WEATHER POSSIBLE INTO TONIGHT...

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

.DAY ONE...This Afternoon and Tonight.
TORNADO.
	RISK...Limited.
	AREA...Eastern Oklahoma.
	ONSET...After 7 PM.

SEVERE THUNDERSTORM.
	RISK...Elevated.
	AREA...Eastern Oklahoma and Northwest Arkansas.
	ONSET...Ongoing.

FLASH FLOOD.
	RISK...Limited.
	AREA...Southeast Oklahoma and Northwest Arkansas.
	ONSET...This Evening.

HEAVY RAIN.
	RISK...Elevated.
	AREA...Eastern Oklahoma and Northwest Arkansas.
	ONSET...Ongoing.

DANGEROUS HEAT.
	RISK...Limited.
	AREA...Parts of Eastern Oklahoma.
	ONSET...Ongoing.

DISCUSSION...
Scattered showers and thunderstorms will remain possible across
eastern Oklahoma and northwest Arkansas through this afternoon. A
limited severe potential will be possible with this activity with
the greater potential over parts of east central into southeast
Oklahoma. Damaging wind and isolated large hail will be possible.
Additional thunderstorms are forecast to develop along a surface
frontal boundary to the west and spread across the region this
evening and overnight tonight. A limited to elevated severe
potential will remain possible through tonight mainly south of
Interstate 44. Damaging wind...large hail and also a low tornado
potential will be possible this evening and tonight.

Locally heavy rainfall will also be possible with the afternoon
showers and thunderstorms. A more widespread chance of heavy
rainfall as well as increasing flash flood conditions will be
possible with the convection this evening and tonight. Forecast
rainfall amounts in the 1 to 3 inch range will be possible over
parts of southeast Oklahoma into parts of west central Arkansas. A
flash flood watch may be issued for these locations later this
afternoon.

SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT...
Activation of the Regional Spotter Network Likely.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.
TUESDAY...Severe Thunderstorm Potential...Heavy Rain Potential.
WEDNESDAY...Thunderstorm Potential...Heavy Rain Potential.
THURSDAY THROUGH SATURDAY...Thunderstorm Potential.
SUNDAY...No Hazards.

EXTENDED DISCUSSION...
The unsettled weather pattern will continue on Tuesday and Wednesday
as an upper level trough approaches from the northwest. Multiple
rounds of strong thunderstorms with very heavy rainfall will be
possible including the potential for flash flooding. Main-stem
river flooding may also become an issue as more widespread rainfall
occurs over the duration of the event.

weather.gov/tulsa contains additional information.