484
FXUS63 KEAX 291816
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
116 PM CDT Sun Jun 29 2025

.KEY MESSAGES...

* Warm and humid conditions continue today.

* Scattered thunderstorms will continue to develop along and
  south of I-70 and move east across the area.

* A SLIGHT RISK for severe thunderstorms into the overnight
  hours primarily west of US Highway 65. Primary risks remain
  damaging winds and locally heavy rainfall.

* Early Work Week: A bit cooler and less humid.

&&

.DISCUSSION...
Issued at 330 AM CDT Sun Jun 29 2025

While the large scale/big picture synoptic pattern has seen little
change and remains on track, the devil is in the details. And the
details are ... messy ... to put it nicely.

Predominantly weak zonal flow remains dominant over the region with
the jet stream remaining displaced northward toward the US-Canada
border and northward. Shortwave trough/disturbance has moved off the
Canadian Rockies and into the Northern Plains and surface high
building in on its heels too has pushed a cool front across the
Northern Plains. As expected, robust convection has initiated
along/ahead of this surface boundary during the evening and
overnight hours. More towards the immediate area, scattered weak/non-
severe convection too has begun to blossom early this morning (~2am)
in response to broad isentropic lift associated with a modest LLJ.
With table set, the short term (24-36) hr forecast remains
remarkably uncertain/low-confidence, though that tends to be the
hallmark of this sort of summer flow pattern. Let`s break the
forecast down into individual pieces...

Ongoing LLJ convection: This activity over eastern Kansas and
central Missouri respectively is largely according to forecast, if
not a couple hours early compared to recent HRRR and other recent
CAM guidance. As such, this tends to be the highest confidence
portion of the next 24 to 36 hrs. Expect this activity to slowly
glide eastward and expand in coverage over the coming few hours,
primarily affecting eastern Kansas and western to central Missouri.
Initially modest PWats around 1.5 are expected to increase in
response to the LLJ induced moisture transport, pushing towards 2
inches this morning. With virtually nil vertical wind shear and weak
steering flow, this activity will act much like air mass
thunderstorms in that individual updrafts will be relatively short
lived. As LLJ wanes mid-late morning, so too should coverage of this
activity. Any "stronger" clusters that are able to produce outflow,
may allow convection to linger into the afternoon over central to
eastern Missouri. Brief heavy rainfall and non-severe wind gusts
would be primary results.

Existing Northern Plains convection: The reason to mention this is
that its evolution may/will carry large ramifications for local
strong/severe potential later this evening and night. As has already
been alluded to, CAM guidance has been and continues to be
relatively all over the map. Recent HRRR for example has recently
depicted existing Nebraska/South Dakota convection as drifting
eastward and staying away from Missouri/Kansas. However,
current/ongoing convection is not acting as such, instead drifting
SE as a marginally strong/severe MCS, generally following existing
broad ML/MUCAPE gradient. This is likely attributed to the weak
easterly steering flow and its inability to more directly influence
the convection. The 00z HRRR and some of the older MPAS/RRFS runs
have better depicted what is ongoing. Should we buy into the latter,
this would potentially push into and track across the area this
morning, and begin to call into question recovery for latter
potential convection. Something to continue to keep a close eye
on...

This afternoon and evening/night convection potential: An unusually
uncertain forecast resides here due to potential convective
evolution(s) mentioned above, resulting in a wide range of
possibilities. Current reality tends to suggest the existing
Nebraska MCS to more closely reflect 00z HRRR/MPAS/RRFS/NSSL-WRF
progressions versus more recent HRRR cycles. As such, worked over
atmosphere and lingering cloud cover could severely hamper the
extreme CAPE scenario that had been mentioned in previous AFDs,
especially with only weak/modest southerly return flow to re-prime
conditions. Do think this may be the current most likely scenario
and as such would limit the strong/severe potential this
evening/night. It would not necessarily eliminate convection, but
would begin to take the higher end wind scenarios off the table.
Conversely, if the MCS peters out before reaching the area and the
LLJ activity does not linger, >3500-4000 J/kg CAPE may remain in
play across the area and keep the existing SPC Slight more in
play. Primary threat would remain strong/damaging winds in that
scenario. Want to reiterate the uncertainty in evolution and the
importance of the next couple/few hours to how this evening may
play out.

Heat: Lesser concern overall here, but uncertainty certainly
carries to the temperature/humidity/heat index portion of the
forecast as well. Hottest scenario would be the Nebraska MCS not
arriving and LLJ activity not lingering, allowing maximal diurnal
heating and heat index values to approach lower 100s in/around
eastern Kansas/western Missouri, and especially within the KC Urban
Heat Island.

Work Week: Frontal boundary moves across the area late overnight
tonight and brings about modest temperature and humidity relief.
Expect temperatures to ease back a handful of degrees into the mid
80s and dew points gradually falling back into the lower 60s early
week. Upper level pattern then begins to take on more amplified
stance, with some degree of ridging over the Central CONUS by mid-
late week, allowing southerly flow to return and push temperatures
and dew points back towards the lower 90s and lower 70s
respectively.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1245 PM CDT Sun Jun 29 2025

Scattered thunderstorms earlier this morning from the system
moving southward from IA/MO with outflow boundaries igniting
more development.Unfortuantely messy forecast situation with the
TAFs. For the TAF sites KSTJ has cleared out of storms but for
the other 3 have linger thunderstorms that should move out after
19-20z. For areas north central MO storms continue to move east
with linger showers from line KIRK and KMBY. While much of the
environment has been worked over by the current storms
extending afternoon, still have a slight risk of thunderstorms
developing primarily areas west of US Highway 65 which. CAMs
models are highly uncertain but have placed Prob30 from 03z-06z
then from 06z have TAF sites with predominant -TSRA. Again
confidence through the earlier time periods reason for prob30
but better confidence in the overnight activity into tomorrow
morning after 06z.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...Curtis
AVIATION...WFO EAX