-- Discussion containing changed information from previous version are highlighted. --
972
FXUS63 KEAX 222332
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
632 PM CDT Sun Sep 22 2024

.KEY MESSAGES...

- Waves of Rain Showers Through Monday Morning

- Cooler This Week, Periods of Sprinkles or Isolated Light Showers

- Heavier Rainfall Possible Friday, Into Next Weekend

&&

.DISCUSSION...
Issued at 236 PM CDT Sun Sep 22 2024

Surface cold front has pushed through the bulk of the forecast area
and will move through the Ozarks region through the remainder of the
evening. The surface cyclone has pushed eastward away from the area.
Main mid-level trough axis is still working across the Central
Plains providing a few more modest vort maxima across our area, and
will be the source for lift of continued shower activity as well as
widespread stratiform cloud cover across the region. Most of the
instability is confined well ahead of the cold front, therefore it
will be very difficult to achieve any kind of robust thunderstorm
activity in our forecast area. Most of the favorable thunderstorm
environment and thus severe weather threat will be well southeast of
the area toward the Interstate 44 corridor. Based on radar trends,
it appears there will be a lull at some point this evening as an
area of weak subsidence moves through. Given the amount of moisture
currently present may still see areas of drizzle or light rain
activity. A stronger surface anticyclone is moving through the
Central Plains and will continue to push the cold front
southeastward. However, as the main mid-level trough axis moves
across the Mid Missouri River Valley later this evening, there will
be some lift and a narrow corridor of convergence across the
southern half of the forecast area that is expected to promote one
more round of light to moderate rain showers. Heaviest activity
would be expected Interstate 70 and southward. Some activity may try
to sneak northward to Hwy. 36, perhaps even the Iowa stateline, but
building surface anticyclone from the northwest should limit the
northward extent. Highest probabilities for exceeding 0.50 inches of
QPF through Monday afternoon are confined to the Ozarks region, with
out southeastern counties most likely to see somewhere between 0.25
and 0.50 inches of rainfall. Probability matched mean values from
the 12z HREF do not produce much more than 0.50 inches, keeping the
heaviest axis closer to Interstate 44. Therefore, any hydro/flooding
related issues will be limited, even areas that have seen nearly 4
inches of rainfall over the past 36 to 48 hours.

The the mid-level trough that provided us forcing for most of this
weekend should move into the Great Lakes Region by Tuesday. However,
area of vorticity breaks away from trough across Canada and will
promote prominent troughing across the central CONUS for much of
this week, likely developing a stronger mid-level closed-low system.
Yesterday, deterministic guidance was greatly spread on the position
of a closed low-system, with the 06z and 12z runs today, they have
come into better agreement that this feature will be more directly
overhead. To start off the week, this should maintain cloud cover
and cooler temperatures. Inner-quartile ranges amongst NBM members
show about 4 to 5 degrees of spread, generally with highs somewhere
in the 70s this upcoming week. Ensemble probabilities for
measurable rain Tuesday through Thursday of this week are generally
under 20 percent. With ridging over the western third of the CONUS
and the mid-level closed-low dropping southward, not much is
expected to develop at the surface, which will greatly limit
forcing. This kind of cooler, Fall like setup seems to favor periods
of drizzle and perhaps a few light showers. Deterministic GFS does
develop a weak convergence zone over east-central Kansas between
Tuesday and Wednesday that outputs some light QPF to around the KS-
MO stateline.

Heading into Friday and next weekend, there is greater
uncertainty. Both deterministic GFS and ECMWF bring in a tropical
system up the Mississippi River Valley Friday into Saturday, and this
could bring quite a bit of moisture that would bring higher
precipitation probabilities into our forecast area. The overall
intensity between the deterministic solutions is quite drastic, and
ensemble suites are quite spread with respect to QPF expected from
this. Depending on the exact track, it could turn out to be a higher
end QPF event, but if the mid-latitude closed-low system manages to
shift eastward, could end up being just a light rain event. For now,
will leave slight chance to chance POPs in the forecast through next
weekend. The 06z and 12z GFS runs from today almost attempt a
Fujiwhara effect with the two cyclones, but then end up becoming
just a deeper system. There is no way to have any confidence in this
kind of solution, but is cool to see in a loop of the model output!
Without any prominent temperature advection regimes, low
temperatures throughout next week are forecast to be in the mid 50s
across most of the area.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
-- Changed Discussion --
Issued at 632 PM CDT Sun Sep 22 2024

MVFR ceilings will persist at most of the terminals (excluding STJ)
until 03-04Z tonight, when overcast cloud bases are forecast raise
to VFR thresholds (between 3-6 kft). Scattered showers currently in
the vicinity of most TAF sites are expected to linger, so VCSH is
included for the majority. There is potential for MVFR conditions
returning tomorrow morning, so ceilings were lowered in the 12Z line
to indicate such a possibility. Winds will be predominantly out of
the north at around 5-10 knots through the period.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...Krull
AVIATION...Hayes