Flash Flood Warning 55, NWS Norman, OK

Area Forecast Discussion
National Weather Service Norman OK
620 PM CDT Sun Jun 21 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 538 PM CDT Sun Jun 21 2026

- An unsettled pattern with multiple rounds of rain/storms are
  expected over the next several days; severe storms and heavy
  rainfall are possible on tonight and Monday nights.

- Below normal temperatures are forecast this week and heat up next
  weekend.

&&

.NEAR TERM...
(Rest of today and tonight)
Issued at 204 PM CDT Sun Jun 21 2026

Hot and humid conditions continue this afternoon with breezy SSE
winds. Latest surface observations show a surface low centered over
the Oklahoma panhandle and the remnant outflow boundary from this
morning's storm complex has largely mixed out and has shifted across
northern Oklahoma as indicated by the return to SSE winds and
rebounding dewpoint temperatures. The synoptic stationary front
remains in Kansas and is rather diffuse, and may not push into
Oklahoma until late tonight or early Monday morning with the
momentum of the high plains convection. Until then, low-level
frontogenesis ongoing over portions of northwest and northern
Oklahoma appear to be the focal zone for initially discrete
supercell thunderstorm development later this afternoon and into
this evening as dynamic ascent increases ahead of a subtle mid-level
shortwave.

A highly unstable airmass near the boundary (3500-4500 J/kg of
MUCAPE), mid-level lapse rates increasing to near 8C/km, and
decreasing CIN, along with high DCAPE will lead to large to very
large hail potential initially with the discrete storms that develop
over NW/N Oklahoma as early as late afternoon (up to the size of
tennis balls). Evolution of storms tonight is somewhat uncertain
given the variance among model outputs. However, storms are expected
to form a complex by late evening and overnight with damaging wind
gusts probable with these storms with isolated gusts of 75+mph
possible. There is also a very low risk of tornadoes, primarily over
north-central Oklahoma late afternoon and evening in proximity to
the boundary. However, we cannot rule out a tornado overnight as
the complex drops southward. The complex of storms is anticipated
to move through central Oklahoma sometime between the pre-dawn
hours and rush hour on Monday (though timing is also uncertain).

In addition to the severe hazards, flash flooding could be an issue
as well with rainfall rates of 1 to 3 inches per hour possible.

Thompson

&&

.SHORT TERM...
(Monday through Tuesday night)
Issued at 204 PM CDT Sun Jun 21 2026

As mentioned above, the risk of severe thunderstorms (all hazards
possible) continues on Sunday night into Monday morning and storm
redevelopment late Monday will depend on how tonight's event
unfolds. Given the anticipated potency of tonight's storms, we
suspect severe risk will be low on Monday afternoon for much of
the area, with the exception of southwest Oklahoma into western
north Texas. Instability increases across the area on Monday night
and another round of thunderstorms with heavy rainfall is
expected on Monday night into Tuesday morning. Storm chances
continue, to a lesser extent, during the day on Tuesday. High
temperatures will range from the low-80's (northern OK) to 90's
(southern OK and north TX) on Monday and Tuesday.

Thompson

&&

.LONG TERM...
(Wednesday through Saturday)
Issued at 240 AM CDT Sun Jun 21 2026

Northwest to west-northwest flow will continue to persist across
the Southern Plains through at least Friday with a mid-level ridge
remaining quasi-stationary across the southwest U.S into northern
Mexico.

With northwest flow aloft, an active weather pattern will
continue as embedded shortwaves within the flow move across the
Plains. As these waves pass by, there will be ongoing chances for
showers and thunderstorms as MCSs and/or effective cold fronts
advance southward. The highest chance for showers and
thunderstorms will generally be in the overnight/early morning
hours. With respect to location, the highest chances will be
across northern Oklahoma with decreasing chances with southward
extent. These complexes of thunderstorms and their effective,
convectively-reinforced cold fronts should result in seasonable to
slightly below normal temperatures.

By the late into the upcoming weekend into next week,
deterministic and ensemble data indicate a mid-level ridge may
strengthen to our east. This would result in hotter and drier
weather across the Southern Plains.

Mahale

&&

.AVIATION...
(00Z TAFS)
Issued at 538 PM CDT Sun Jun 21 2026

Two rounds of storms may impact our terminals through the forecast
period degrading our terminals for periods to an MVFR to IFR
category with lowering CB ceilings and reduced visibilities in
heavy rain at times. The first round of strong to severe convection
will be along a cold front & mid-level shortwave coming down the
Central Plains expected to start pushing into northern Oklahoma
around 03Z and reaching terminals near the I-40 corridor around
07Z and eventually crossing the Red River into terminal KSPS by
09Z. A second round of storms will be in association with a
second mid-level shortwave coming off the Southern High Plains
which may impact our terminals again from 12-18Z. Due to some
uncertainties with timing did extend lower probabilities of 30%
for storms beyond 18Z. Surface winds will shift northeast behind
the cold front but in actuality expecting surface winds to be
gusty and variable in direction due to the convection and outflow
from the storm activity.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  72  85  68  86 /  70  60  70  50
Hobart OK         72  90  68  92 /  40  40  70  10
Wichita Falls TX  76  95  72  95 /  20  30  60  10
Gage OK           67  84  64  89 /  60  40  40  20
Ponca City OK     68  81  65  83 /  70  20  50  30
Durant OK         78  92  75  91 /  50  50  60  40

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Heat Advisory until 8 PM CDT this evening for OKZ005>008-011>013-
     015>027-033>039-044-045.

TX...Heat Advisory until 8 PM CDT this evening for TXZ083>090.

&&

NEAR TERM...01
SHORT TERM...01
LONG TERM....10
AVIATION...68