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523
FXUS63 KEAX 150510
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
1210 AM CDT Sat Jun 15 2024

.KEY MESSAGES...

- Warm and Humid For The Next Few Days

- Isolated Showers/Storms Saturday

- Warm and Humid Next Week, Periods of Rain/Showers Likely

&&

.DISCUSSION...
Issued at 345 PM CDT Fri Jun 14 2024

Amplified ridge axis currently sits across the Central Plains  with
strong surface anticyclone centered over the SD-MN-IA border.
Thermal boundary reinforced by last night`s convection has been
pushed southward into the Ozarks Region. Although weakening, AVA
will continue through the evening, with subsidence helping to keep
skies mostly clear. The boundary layer still remains moist, thus
with diurnal destabilization will see a few cumulus clouds through
the evening. There is a short-wave trough near the Four Corners
Region that is pushing the current H5 ridge axis eastward and clears
our forecast area during the early morning hours of Saturday.
Saturday late morning, H5 height falls start with weak surface
pressure falls following in response to that across the lower
Missouri River Valley. This along with the thermal boundary in the
southern Ozarks will compete with the surface anticyclone being
forced into the Great Lakes Region and increase convergence into the
early afternoon hours. Expecting isolated to scattered showers and
storms to develop along this line of forcing. While a hot and humid
airmass is in place, mid-level lapse rates are not overly robust,
and this keeps MLCAPE values on lower side for this time of year.
Further, although a vort max is moving toward the region, overall
mid and upper-level flow is rather weak across most of our forecast
area limiting the available deep layer shear. Therefore, the severe
threat will be limited by weaker thermodynamics on Saturday. Our far
northwestern Missouri Counties are clipped by the SWODY2 Marginal
Risk, as this gets into the better mid-level lapse rates that could
foster more buoyant parcels. Main concern for thunderstorms in our
far northwestern counties would be hail around quarter size and
winds around 60 MPH. Elsewhere, a few stronger cores could produce
around dime size hail and wind gusts between 40 and 50 MPH at times.
The airmass Saturday afternoon is characterized by PWATs between 1.5
and 1.75 inches. QPF from the HREF mean produced between 0.25 and
0.50 inches of rainfall across areas mainly north of Interstate 70
for Saturday, and a localized pocket of 0.50 to 0.75 inches in far
northwest Missouri where stronger core may be realized. Local
probability matched mean QPF has a few pockets of 1.25 inches in our
far northwestern counties. The GEFS probabilities for exceeding 0.10
are above 80 percent toward the IA-NE-MO point, with 50 to 60
percent probabilities extending toward the Interstate 70 corridor.
For a threshold of exceeding 0.50 inches, probabilities are around
40 to 50 percent for our far northwest counties, then steadily drop
to less than 10 percent approaching the Interstate 70 corridor.
Overall, hydrological issues should be minimal, but if a stronger
core produces heavier rainfall over a developed area, may result in
some localized flooding and rises on local creeks/streams. Light
activity may continue late Saturday Night as the main lobe of
vorticity moves across the area though the better surface
convergence is progged to move into Iowa along the effective thermal
boundary.

Next week, the synoptic pattern will be characterized by an
anomalously strong east coast ridge. All clusters of the WPC Cluster
Analysis indicate a strong signal for this pattern over the east
coast, with troughing over the Pacific Northwest that sets up
southwesterly flow across the Central CONUS. NAEFS guidance indicates
the potential for H5 heights to be pushing if not reach a
climatological max. For our forecast area, this will have two
impacts. The first, will be continued hot and humid conditions
across the region. A look at box and whiskers statistics through the
end of next week shows an inner-quartile spread between 90F and 97F
for most points in our forecast area. With dewpoints in the mid to
upper 60s, this will push heat index values into the upper 90s and
eventually triple digits. The second, is multiple rounds of showers
and storms with warm humid airmass in place. Subtle short-wave
troughs will move through the southwesterly flow that will likely
provide enough convergence to produce rain shower and thunderstorm
activity. Thermodynamically, certainly will be enough energy to
support severe potential for a few of these days. However, current
deterministic medium to long range guidance suggests the stronger
mid and upper-level flow remains north of our area, which may limit
the potential for storms throughout the week to organize across our
area. The Colorado State Machine learning probabilities seem to be
latching onto this, focusing greater probabilities for severe
potential for the Upper Midwest and western Great Lakes Region than
it does for the lower Missouri River Valley. And then some higher
potential more over the High Plains where the dryline may come into
play. We will see how the pattern evolves though. Changes in the
strength of the east ridge could effect the placement mid-level
southwesterly flow across the Central CONUS. GEFS probabilities for
any measurable precipitation in a 24 hour period are above 60
percent for most of the area next week, and above 30 percent for a
threshold 0.10 inches of QPF. Currently, Wednesday and Thursday of
next week hold the highest probabilities for shower and storm
activity with a few stronger short-wave perturbation and mid-level
vort maxes ejecting out of the Rockies, then forced into the Great
Lakes on the backside of the east coast ridge.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
-- Changed Discussion --
Issued at 1207 AM CDT Sat Jun 15 2024

VFR conditions are expected to remain until tomorrow morning when
showers and thunderstorms may move into the area (30%-50%). At this
time, confidence is lower for convective development for MKC,MCI,and
IXD. For now, vicinity showers and thunderstorms were left in
the TAF for the previously mentioned sites. Showers and
thunderstorms should then move to the east of the terminal by
tomorrow afternoon. VFR conditions are expected once the storms
move out of the area with an occasional gust around 20 mph
through the day. Winds will weaken and shift to the south by
tomorrow evening.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...Krull
AVIATION...Collier