975
FXUS64 KTSA 220530
AFDTSA

Area Forecast Discussion
National Weather Service Tulsa OK
1230 AM CDT Wed May 22 2024

...New AVIATION...

.UPDATE...
Issued at 932 PM CDT Tue May 21 2024

Strong to severe thunderstorms producing large hail & damaging
winds were ongoing across E OK and parts of NW AR this evening
along/ ahead of a cold front. As of writing, a 3" hailstone was
the largest reported this evening... associated with the
thunderstorm which had moved through the south Tulsa metro area.
The frontal boundary has slowed down/ stalled for portions of NE
OK this evening. With subsidence & lack of low level forcing
occurring north of the ongoing activity (along the I-40 corridor
in E OK), believe any chance of additional storms in the wake of
earlier convection should remain fairly minimal this evening into
early tonight. Otherwise, storms in E-Central OK and NW AR will
continue to drift south and east over the next few hours, with the
coverage & severe threat becoming more isolated by late this
evening/ early tonight as forcing wanes. Thus, will allow the
Tornado Watch to expire at 10 PM.

As 850mb winds shift out of the south again later tonight east of
a low pressure center in N TX, increasing elevated instability
will surge back northward across C & E OK. At the surface, the
frontal boundary is forecast to sag south before stalling near the
I-40 corridor through the overnight hours. Expect elevated
showers and storms to redevelop late tonight/ early tomorrow
morning across E OK as low-level isentropic ascent increases
associated with the strengthening LLJ. This is supported by CAMs
which begin to produce a fairly large precip footprint during the
09-12z timeframe. The environment will continue to support a
threat for severe weather during this time, with all hazards
possible along the boundary and primarily a large hail threat to
the north.

Other than editing PoPs to match current trends, much of the
ongoing forecast was in good shape with only some other minor
edits to temps and dew points.

&&

.SHORT TERM...
(Through Tonight)
Issued at 119 PM CDT Tue May 21 2024

Warm, humid, and breezy conditions will continue through this
afternoon and evening. Storm chances will ramp up later this
afternoon and into the evening, continuing into the overnight hours
as a cold front moves into the area from the northwest. Model
guidance continues to show a deeply unstable atmosphere with
MLCAPE in excess of 3000 J/Kg through the afternoon and evening
south of the front. Surface-850 hPa specific humidity will be near
the 99th percentile for this time of year with IVT also near the
99th percentile as a consequence of an usually strong low pressure
to the northwest enhancing the southerly flow.

Initial convective initiation has already begun in south-central OK.
These elevated storms will move into southeast OK the next 2 hours.
The main severe hazard will be hail. Convective initiation along the
front is expected around 3-6 PM with a line of storms forming along
it. There will also be the potential for additional isolated
cells anywhere east or south of the front. These storms will be
capable of all severe hazards, including large hail, damaging
winds, tornadoes, and heavy rainfall leading to flash flooding.
CAMs remain a bit uncertain with respect to how far south along
the boundary storms will form. They also remain uncertain with the
coverage and intensity of storms ahead of the front. With this in
mind, the best coverage and intensity of storms will likely be
across far northeast OK and northwest AR during the early evening.

By late in the evening more widespread storm activity will develop
across southeast OK. Further north, storms will continue to develop
along the front, which will slowly sag south in the vicinity of I-
40. Some areas with repeated rounds of storms will see localized
flash flood potential. Due to recent rains, as well as the
expectation of continued heavy rain Wednesday, and low level
moisture remaining near the climatological max for this time of
year, a Flood Watch was issued through Friday morning to account
for this threat. CAM guidance shows a resurgence of elevated
storms along and behind the front in the 9-12Z period across the
area, but southeast OK in particular. These storms will once again
have the potential to become severe. Discrete cells and cells
north of the front would be hail dominant, but any storms near the
boundary would be capable of all severe hazards.

&&

.LONG TERM...
(Wednesday through Tuesday)
Issued at 119 PM CDT Tue May 21 2024

The cluster of storms mentioned at the end of the short term period
will progress east to northeast into northwest AR bringing
widespread heavy rainfall with some severe potential continuing. As
storms (presumably) grow upscale into a line, the threat of strong
winds would become dominant, but other severe hazards would remain
possible. CAM guidance is all over the place for later in the day
Wednesday, but the general theme is that multiple rounds of
additional showers and thunderstorms are likely, but will continue
to focus in southeast OK and northwest AR. As the cold front will be
near or south of the Red River by Wednesday, high temperatures will
be much lower. Highs in the mid 70s will be common north of the
boundary, except perhaps low 80s near the Red River. Low
temperatures north of the boundary will be in the low to mid 60s
and low 70s near and south of it.

For Thursday the remnant cold front will lift north, but it will
become diffuse and wash out. With warm and humid air streaming back
through the area and yet another shortwave trough moving through,
widespread storms are expected to develop again. Similar to the
preceding days, anomalous instability, moisture, and wind shear will
be present so severe weather is expected. Areas of heavy rainfall
will also occur.

Ensemble guidance is in decent agreement that we will get a break
from the storms Friday, with just some lower potential across the
terrain in Arkansas. Saturday will see storm chances resume, with
some lingering probabilities into Sunday. By early next week
ensemble guidance is in excellent agreement that a large ridge will
build across the Great Basin, bringing much warmer air back into the
area under northwest flow. However, smaller scale details such as
how strong the ridge will be or where it will center are still
unknown. About 40% of guidance position the ridge in a way that
would be favorable for nocturnal MCS activity, but given the lead
time will just go with NBM PoPs for now.

&&

.AVIATION...
(06Z TAFS)
Issued at 1224 AM CDT Wed May 22 2024

Persistent cluster of storms west of KFSM should slowly progress
east early in the forecast period, with additional showers and
storms anticipated between 10-12z. Favored area at this time looks
to be southeast of I-44. MVFR vis at KFYV is not currently
expected to persist more than a few more hours as showers
eventually move into that area. Potential still there for multiple
rounds of convection from NW AR through SE OK, with current
expectation that MVFR conditions will eventually become more
widespread from mid afternoon on.

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   63  82  68  87 /  40  50  60  10
FSM   66  84  67  88 /  70  60  70  10
MLC   65  82  69  88 /  70  60  50  10
BVO   58  81  64  84 /  30  50  50  10
FYV   61  80  64  84 /  70  60  70  20
BYV   61  80  64  83 /  60  50  70  30
MKO   64  80  66  86 /  60  60  60  10
MIO   61  80  66  83 /  40  50  60  20
F10   63  80  68  88 /  60  60  50  10
HHW   66  82  69  88 /  70  60  50  10

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch through Thursday evening for OKZ049-053-072>076.

AR...Flood Watch through Thursday evening for ARZ019-020-029.

&&

$$

SHORT TERM...06
LONG TERM....06
AVIATION...14