Flooding in Arkansas, May 22 to 31, 2019

Area Forecast Discussion
National Weather Service Tulsa OK
301 AM CDT Wed May 22 2019

.DISCUSSION...
Main forecast concerns are the potential for severe thunderstorms,
including tornadoes, and additional flash flooding late this
afternoon and into tonight.

Low level moisture will increase areawide today as southerly
winds increase in response to an upper level trough swinging into
the southwestern United States and increasingly amplified flow
aloft. Very high instability is expected to develop by mid to late
afternoon, with the highest values likely to be found along and
north of Interstate 44. Largely isolated to scattered
thunderstorms are expected to develop during the late afternoon
and evening across portions of northeast Oklahoma and perhaps far
northwest Arkansas. Increased ridging into the areas south of
Interstate 44 should keep convection suppressed in that area, and
there is a nonzero chance that it could keep thunderstorms from
developing this far south completely. However, the latest data are
trending toward at least some development. Any thunderstorms this
afternoon and evening will have a high likelihood of being
supercellular and severe, given the very high instability and
sufficient deep layer shear. 0-1km shear values from 30 to 40 kts
will more than support a strong tornado threat, which is also
supported by various CAM solutions. The overall thunderstorm
potential will largely shift northward into Kansas and Missouri
early tomorrow morning.

In addition to the severe weather threat later today, the
antecedent conditions across a good chunk of northeast Oklahoma
will support a flash flood threat with any thunderstorms, even
though QPF values are fairly modest. A Flash Flood Watch will be
posted for areas currently under Areal Flood Warnings from late
this afternoon through the overnight hours.

Thunderstorm chances through the rest of the week and through the
weekend will continue to be focused across portions of northeast
Oklahoma and at times, far northwest Arkansas, with the upper
level pattern featuring troughing in the western United States and
ridging along the Gulf Coast and southeastern United States
remaining fairly stagnant. Temperatures should be above normal
through this period as well.

The pattern will finally begin to change toward the middle part of
next week, which could lead to thunderstorm chances shifting
farther east into more of the forecast area by Wednesday. Will
keep pops fairly conservative for now, given continued timing
differences.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   85  69  86  70 /  60  60  10  10
FSM   88  72  89  69 /  10  10  10  10
MLC   84  72  86  70 /  20  10  10  10
BVO   83  67  85  70 /  60  70  30  20
FYV   84  68  85  68 /  10  20  10  10
BYV   86  69  86  67 /  10  20  10  10
MKO   85  69  86  69 /  20  20  10  10
MIO   84  68  86  69 /  50  70  10  10
F10   85  70  86  69 /  30  30  10  10
HHW   85  72  86  68 /  10  10  10  10

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Flash Flood Watch from this afternoon through Thursday morning
     for OKZ054>064-066-067.

AR...None.
&&

LONG TERM....22

Hazardous Weather Outlook
National Weather Service Tulsa OK
510 AM CDT Wed May 22 2019

ARZ001-002-010-011-019-020-029-OKZ049-053>076-231015-
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-
510 AM CDT Wed May 22 2019

...SEVERE STORM AND FLASH FLOOD THREATS TONIGHT...

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

.DAY ONE...Today and Tonight.
TORNADO.
	RISK...Elevated.
	AREA...Northeast Oklahoma and Far Northwest Arkansas.
	ONSET...After 4 PM.

SEVERE THUNDERSTORM.
	RISK...Significant.
	AREA...Northeast Oklahoma and Northwest Arkansas.
	ONSET...After 4 PM.

HEAVY RAIN AND FLASH FLOOD.
	RISK...Limited.
	AREA...Northeast Oklahoma.
	ONSET...After 4 PM.

SIGNIFICANT WINDS.
	RISK...Limited.
	AREA...Eastern Oklahoma and Northwest Arkansas.
    ONSET...After 9 AM.

DISCUSSION...
A significant threat for severe thunderstorms, including the
potential for very large hail and tornadoes, will exist across
portions of northeast Oklahoma and far northwest Arkansas from mid
to late afternoon into the evening hours today. In addition, flash
flooding could develop once again as a result of the very wet
antecedent conditions and the expected additional rainfall.

Isolated to scattered thunderstorms are expected to develop across
portions of northeast Oklahoma and far northwest Arkansas this
afternoon and evening, especially in areas along and north of
Interstate 44. A cap in place will likely keep coverage from
becoming too widespread, with a nonzero but very low possibility
by that it could suppress thunderstorm development entirely. Very
high instability and strong deep layer wind shear will support
supercell thunderstorms, with strong low level shear leading to
an elevated threat for tornadoes, including the potential for
strong tornadoes. Much of this activity will shift northward into
Kansas and Missouri after midnight.

Locally heavy rainfall would also accompany any thunderstorms, and
with high water remaining from the recent heavy rains, flash
flooding will be quick to onset. A Flash Flood Watch is in effect
for portions of northeast Oklahoma. Widespread and significant
mainstem river flooding also continues with several river flood
points forecast to exceed their major flood stages.

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

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.
THURSDAY THROUGH SUNDAY...Thunderstorm Potential.
MONDAY AND TUESDAY...No Hazards.

EXTENDED DISCUSSION...
Thunderstorm chances will persist for the remainder of this week
and into the weekend, with the focus being parts of northeast
Oklahoma and at times, far northwest Arkansas. Given that this
area may not have sufficient time to dry out, flash flooding could
continue to be a concern, in addition to the expected long
duration mainstem river flooding.

While an increasing upper level ridge should keep much of the
area south of Interstate 44 dry into early next week, the weather
pattern should change somewhat by the middle of next week, leading
to more widespread precipitation chances.

weather.gov/tulsa contains additional information.