974
FXUS64 KOUN 231757
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
1257 PM CDT Thu May 23 2024

...New AVIATION...

.UPDATE...
Issued at 1209 PM CDT Thu May 23 2024

Watching a complex severe weather forecast this afternoon and
evening. Boundary layer moisture return has been extremely robust
this morning following the overnight round of convection. The
outflow boundary from those previous storms could be seen in surface
observations as a sharp warm front across central Oklahoma; surface
wind fields on the Oklahoma Mesonet have shown a distinct diffusion
of this front over the last 2 hours. With that said, dewpoints in
northwest Oklahoma are in the mid-60s with a distinct gradient to
dewpoints in the low-to-mid 70s across western north Texas and
southern Oklahoma.

A stratus deck is also shown on satellite across most of the area,
particularly near the 100th meridian. Given the moisture advection
ongoing, there are some questions about how long this takes to mix
out. If stratus does linger into the afternoon, the severe risk
would likely be reduced. Over the past hour, however, GOES satellite
has shown some thinning of the stratus across the 100th meridian and
corresponding eastern portions of the Texas panhandle, which
coincides with an easterly push of the dryline off of the Caprock.
The expectation is that the western fringe of the cloud cover will
continue to downscale into cumulus over the next several hours,
which will allow for partial insolation.

The number of storms we receive is similarly in question and in part
dependent on how much insolation we receive. Most members of the
HREF/MPAS do try to cue up at least one or a few storms by late this
afternoon in western Oklahoma, with a particular focus on the triple
point between the effective warm front and the dryline. Meanwhile,
another area will be watched in southern and central Oklahoma where
some models have shown a signal for convection initiation within a
warm advection regime. There appears to be a negative correlation
between storm coverage in the two regimes; in other words, more WAA
storms to the east could reduce or even remove storm coverage along
the dryline later.

The early storms, should they develop, will have access to 3,000-
4,000 J/kg of MLCAPE and sufficient bulk shear for the development
of supercells. Low-level shear will be weak, so the main concern
would be for severe hail and damaging winds, but a very low tornado
risk would accompany these storms. Off to the west, any storms that
develop along the dryline will initially be favored to become
supercellular and produce large to very large hail. There is a
noticeable uptick in the LLJ on model guidance beginning about 8:00
pm, so there will be a window for any established supercells to
produce tornadoes this evening as they move eastward.

Meister

&&

.SHORT TERM...
(Today and tonight)
Issued at 348 AM CDT Thu May 23 2024

Severe weather potential will remain the main weather message on
Thursday. For early this morning (through ~sunrise), widely
scattered thunderstorm development is expected to continue across
portions of southeast Oklahoma. This activity is likely being
fostered in part by increasing warm air advection/mass response
and cold pool effects with recent storms. Despite a stable
boundary layer, objective analysis continues to show an
environment favorable for at least limited strong to severe storm
potential. Large hail and gusty winds will be the main concerns
with activity this morning. Additionally, areas of fog may develop
(along/south of Interstate 40) as aforementioned moisture
transport spreads northward through the area. Couldn`t rule out
localized dense fog, especially along and east of a Holdenville-
to-Waurika line.

Otherwise, attention will turn towards an additional (more
impactful) round of severe thunderstorms late this afternoon into
evening. In between, low clouds/drizzle and perhaps a few
thunderstorms may develop as low-level moisture advection
continues through much of the day, and as an effective warm front
lifts through the area. Severe weather chances are generally low
through 2-3 PM, though one or two severe storms cannot be ruled
out (mainly across west-central into eastern Oklahoma).

After ~4-5 PM, focus for severe weather will reside near a
sharpening dryline in vicinity of the 100th meridian. While the main
synoptic support will be associated with a wave emerging across the
Northern/Central Plains, a branch of the subtropical jet (across
portions of central Texas) looks to remain active through the day.
Additionally, a combination of at least filtered insolation and
rather unseasonable moisture (HREF mean ~68-72 degrees) will help
erode residual elevated warm layers (the `cap`) into the mid-
afternoon. The result will be the potential for scattered
development of organized/severe storms near and east of the
dryline, even amidst a weakly forced regime.

The forecasted mesoscale environment will be quite favorable for
organized (supercell) thunderstorms, posing a risk for all storm
hazards. Initially, large to very large hail will be the favored
hazard owing to steep lapse rates and strong cloud-bearing wind
shear. Towards mid-evening/sunset, as a nocturnal low-level jet
becomes established, concern for tornadic potential will likely
increase with any ongoing supercell. The most established storms
may take some time to fully meet their demise after sunset,
especially when considering continued mass flux late this
evening. For now, storm intensity and concern for severe weather
is expected to wane towards ~11 PM-Midnight.

In addition to severe weather concern, potential for at least
limited heavy rainfall and flooding continues across portions of
southeastern Oklahoma. While forecast confidence/signal is not as
strong compared to previous cycles, enough potential remains to
warranted continuation of ongoing Flash Flood Watch through early
Friday morning.

Ungar

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 348 AM CDT Thu May 23 2024

Friday: Low potential for storms and severe weather looks to
develop across far southeastern Oklahoma during the afternoon/evening.
As the aforementioned north-central CONUS wave lifts into
portions of the western Great Lakes, a trailing front is expected
to push through the area beginning early Friday morning. A few
light rain showers may be noted during and just behind frontal
passage on Friday morning.

Otherwise, very low (~20%) potential for additional storm
development is currently anticipated by Friday afternoon/evening
across far southern/southeastern Oklahoma. How far the front
ultimately advances (southward) through the day will determine the
severe weather risk for counties near the Red River, as the
mesoscale environment will support a hail/wind risk with sustained
storms.

Saturday: A potent severe weather event is possible across portions
of the area/region. A strong upper wave ejection is expected across
the Plains through the day. Strong mass response is again
expected ahead of this feature. As forcing overspreads a dryline,
expected to reside across western into west-central Oklahoma into
the afternoon, scattered thunderstorm development is expected. The
progged mesoscale environment will strongly favor strong
supercells, posing a risk for large hail, damaging winds and
tornadoes (including significant events of each). This is a day
that bears close watching, as any storm will be capable of
significant and impactful outcomes.

Sunday-Next Week: Transition towards mostly dry and seasonable
weather is expected. As the Saturday system departs to the east,
a stretch of mostly dry weather is expected to ensure. Pending the
strength of the frontal intrusion on Sunday, temperatures into
the early-midweek may run near to slightly cooler than average for
the last days of May.

Ungar

&&

.AVIATION...
(18Z TAFS)
Issued at 1237 PM CDT Thu May 23 2024

Current stratus deck will slowly scatter with increasing
visibilities as all terminals should return to VFR conditions
around 20-21Z. Isolated thunderstorms will be possible and could
impact some of our terminals between 22-04Z with probabilities up
to 50 percent. Although storm activity could reduce conditions
below VFR conditions, expecting another stratus deck to lower
ceilings to MVFR to IFR between 05Z-10Z with low confidence of
reduced visibility`s in fog down to 2 miles at some terminals. A
cold front will be pushing into northern Oklahoma after 12Z as
surface winds will be shifting out of the north behind the front.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  82  67  83  62 /  50  50   0   0
Hobart OK         89  65  86  60 /  30  30   0   0
Wichita Falls TX  89  70  90  65 /  30  30   0   0
Gage OK           91  58  81  54 /  20  20   0   0
Ponca City OK     83  65  82  57 /  40  40   0   0
Durant OK         84  70  90  68 /  50  50   0  20

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch through late tonight for OKZ032-041>043-046>048-
     050>052.

TX...None.
&&

$$

SHORT TERM...34
LONG TERM....34
AVIATION...68