936
FXUS64 KOUN 250903
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
403 AM CDT Sat May 25 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Today and tonight)
Issued at 403 AM CDT Sat May 25 2024

Significant severe weather is possible late this afternoon and this
evening, but there are also potential complications.

A shortwave in southern California is progged to move toward the
southern Plains this afternoon, although it is also progged by most
models to weaken as it approaches.

In the broad sense, very high instability and strong deep layer wind
shear are forecast across the area today. With these parameters,
thunderstorms that do develop today will be capable of producing
large hail, strong winds, and tornadoes (and potentially strong
tornadoes) if storms can take full advantage of these parameters.
But there are also some questions and things we will be watching
through the day.

First, low-level moisture will be a relatively late arrival, and
there will likely be a limit on how far north the best moisture
advects. The front that moved through the area yesterday has allowed
dry low-level air into the area. The current dewpoint at KCSM and
KWWR is 44 with KSPS down to 58 with a north component to the
wind. Dewpoints have also mixed out across portions of northeast
Texas behind yesterday`s convection and some of the models do not
recognize this yet. There are isolated dewpoints in the 70s in
north central Texas, but the more widespread 70s dewpoints are
currently south of the metroplex and winds in that area are
currently light. Southerly winds will increase today and start
allowing higher dewpoints to start advecting north, but some of
the models are beginning to recognize that (a) it may not advect
too far north, and (b) it likely will not advect all the way west
to the dryline progged to set up in the eastern Texas panhandle or
far western Oklahoma. With the latter, any storms that develop
near the dryline would likely be high-based initially, and the
question would be if they could prevent becoming outflow dominant
before moving into better moisture. But even these storms would
have the potential of producing large hail and strong winds.

So another question is will storms be able to develop in the warm
sector, perhaps with confluence near the moisture gradient east of
the primary dryline. The best pressure falls will be in northwestern
Oklahoma associated with the deepening low in eastern
Colorado/western Kansas, and we may not see significant backing of
the low-level winds apart from northwest Oklahoma, but low-level
moisture likely more limited there. And even if portions of
western Oklahoma mix out more with the shallow low-level moisture,
the progged 850 mb flow is still strongly southerly, so we may
not see much veering of the flow west of the moisture gradient to
get decent confluence except on the dryline itself. But we have
seen cases where even subtle confluence is enough to get at least
isolated storm development, and some of the CAMs do suggest some
backing so we definitely can not write off the potential.

Classic jet dynamics suggest that most of Oklahoma would not be in
the most favorable area of lift with the best upper-level
diffluence and associated rising motion that looks to be mostly
across Kansas and perhaps far northern Oklahoma. But could this be
offset by any sub-synoptic features?

As far as tornado potential, the 0-1 km shear is not terribly strong
until after 00Z when the low-level jet increases and therefore
increases the low-level shear vector. But surface-based CIN will be
increasing then as well so will there be any surface-based storms to
utilize this low-level shear?

Although there are these uncertainties and factors that complicate
the forecast and we will be watching these closely today, the
instability/shear parameter space that will exist over the area will
keep the potential for significant severe thunderstorms including
large hail and strong tornadoes if things come together right, so we
encourage our partners and residents to prepare for this potential
and keep updated with weather situation today and tonight.

Most models develop at least widely scattered thunderstorms late
this afternoon or early this evening. The 06Z NAM and 00Z GFS both
look to be suffering from convective feedback so may be a bit too
aggressive with storm coverage. Whatever storms do develop should
move east out of the area late tonight or very early Sunday
morning. /26

&&

.LONG TERM...
(Sunday through Friday)
Issued at 403 AM CDT Sat May 25 2024

The weather should be quiet Sunday and Monday behind this system and
behind a Pacific front that brings a drier (but not significantly
cooler) airmass into the area. Some thunderstorms will be possible
Monday night into Tuesday with isentropic lift as moisture begins
returning north. But it also looks like easterly to southeasterly
low-level flow persists into the middle and later part of the week
allowing for daytime thunderstorm development over the high plains
and into the area as mesoscale convective systems in the evening and
overnight hours each night. /26

&&

.AVIATION...
(00Z TAFS)
Issued at 956 PM CDT Fri May 24 2024

Some stratus will be possible early Saturday with MVFR ceilings.
Otherwise, VFR ceilings are expected with mid and high clouds.
Winds will gradually shift towards the E and then the SE or S
this TAF period. Some storms will be possible late Saturday
afternoon/evening. Chances are currently too low at some places
for mention in TAF. Strong, variable winds and large hail will be
possible with the storms Saturday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  89  70  91  61 /  20  30   0   0
Hobart OK         94  65  94  61 /  20  20   0   0
Wichita Falls TX  95  71  96  64 /  20  30   0   0
Gage OK           92  60  89  55 /  20  10   0   0
Ponca City OK     87  68  88  58 /  20  30   0   0
Durant OK         88  72  94  66 /  20  20   0   0

&&

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

$$

SHORT TERM...26
LONG TERM....26
AVIATION...25