257
FXUS64 KOUN 211144
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
644 AM CDT Tue May 21 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 320 AM CDT Tue May 21 2024

The main weather concern in the short term will be the return of severe
weather potential, beginning this afternoon and continuing into
the overnight period. Early morning water vapor imagery captures a
shortwave trough quickly crossing the Great Divide. This feature
is forecast to continue deepening while sliding towards the Corn
Belt by this afternoon/early evening.

Synoptic support will be rather modest across our area (given
aforementioned wave evolution), with ~neutral height tendency
through the afternoon. Still, with a dryline feature/seasonable
low-level moisture/filtered insolation, will maintain very low
probability (~20%) mentions for storm development this
afternoon/evening. However, should a storm form and sustain,
severe weather (hail/wind) would be likely given strong wind
shear/instability in place. The tornado risk appears very low,
primarily owing to veered low-level flow. This potential looks to
focus in areas along and east of a Stillwater to Henrietta TX
line.

After sunset/into the overnight, a trailing cold front is expected
to sink southward across the area. Expectation is for scattered
to potentially widespread convective development as the cold front
intercepts the retreating dryline early Wednesday morning (after
~4 AM). Continued severe weather risk is expected with this
activity, though main hazards will be dependent on storm evolution
(relative to frontal position). With the composite front expected
to continue advancing slowly southward, combined with
east/northeastward motion vectors for individual storms, a quick
transition towards `elevated` nature (hail risk) may ensure with
convection. However, any development south of/or interacting
favorably with the front would carry an all hazards
(hail/wind/very low tornado) risk Wednesday morning.

Ungar

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 320 AM CDT Tue May 21 2024

Wednesday: Severe weather chances will continue through a
potentially large portion of the day (pending evolution of surfaces
features and upper wave timing). Convection, potentially
sporadically severe, is expected to be ongoing around daybreak
across portions of central into southern Oklahoma. Activity is
expected to advance into eastern Oklahoma through the mid-morning
time frame. Depending on how far morning convection modifies the
surface front (southward), additional severe storms are possible
across south-central into southeast Oklahoma during Wednesday
afternoon/evening ahead of an emerging `southern stream` upper wave.
Will continue the main message of a hail/wind/low tornado risk
across southern zones, though position of surface front/airmass
recovery in the wake of morning storms will play a significant
role on whether surface-based storms/outcome remain favored. Heavy
rainfall and flooding will also become an issue across southern
Oklahoma by Wednesday afternoon evening, especially where repeated
rounds of heavy storms occur over the preceding 24-hours. A Flood
Watch may become necessary at later updates if confidence in this
potential continues to increase.

Thursday: Severe weather potential will continue, with a larger
swath of the CWA under risk compared to prior days. A broad belt of
50+ kt mid/upper flow will continue across the southwestern
US/Plains. A majority of guidance members/grand ensemble show
potential for multiple low-amplitude wave ejections across the
Plains during the afternoon/evening. While the midweek front is
expected to reside across portions of north-central Texas by
daybreak on Thursday, sufficient mass response is expected to
occur during the day ahead of the aforementioned features. While
specifics on storm coverage and evolution are uncertain, a
combination of dryline and warm air advection initiation regimes
are possible across our area during the afternoon/evening. Severe
weather risk would likely accompany any sustained storm through
the late evening period. Heavy rainfall/flooding concern may also
continue, especially if convective focus resides across areas
where highest totals occur earlier in the week (i.e. south-
central into southeast Oklahoma).

Friday-Holiday Weekend: At least low probability storm chances look
to continue into the weekend, with nature/magnitude of severe risk
TBD. Broad southwesterly flow is forecast to be maintained heading
into the weekend. This will offer at least low potential for storms
during the period. By early next week, upper ridging looks to return
across the western US, potentially promoting a return towards drier
times.

Ungar

&&

.AVIATION...
(12Z TAFS)
Issued at 639 AM CDT Tue May 21 2024

MVFR cigs will spread northward ahead of dryline this morning,
affecting KDUA/KOKC/KOUN/KSWO/KPNC before winds veer through
15-16Z and allow cigs to erode. VFR cigs will likely hold on at
KDUA into the afternoon. Gusty south winds will veer to southwest
to west most terminals before shifting to northerly this afternoon
across northern Oklahoma and spreading slowly southward tonight.
TSRA this afternoon expected to stay north and east of terminals,
at least chances too low for TEMPO or PROB30. Probability for TSRA
will increase toward and after the end of forecast period across
central and southeast Oklahoma terminals so will mention PROB30
last few hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  93  64  77  62 /  10  20  40  40
Hobart OK         95  61  79  61 /   0  10  20  20
Wichita Falls TX  95  71  82  66 /  10  10  50  40
Gage OK           90  54  79  56 /   0  10  10  10
Ponca City OK     92  59  76  59 /  10  30  30  20
Durant OK         89  73  85  66 /  20  10  60  70

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&

$$

SHORT TERM...34
LONG TERM....34
AVIATION...11