377
FXUS63 KEAX 041117
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
517 AM CST Thu Dec 4 2025

...Updated 12z Aviation...

.KEY MESSAGES...

- Cold Thursday Morning, Especially North-Central Missouri

- Slightly Warmer Friday

- Precipitation Potential Saturday Into Sunday; Still A Lot of
  Unknowns

&&

.DISCUSSION...
Issued at 329 AM CST Thu Dec 4 2025

Deep closed-low system continues to sit over Hudson Bay with another
deep, positively tilted trough axis that as of 08z is just starting
to move east of the Four Corners Region. Mid and upper-level flow
over the Missouri River Valley has turned more zonal, but remains
brisk with strong height gradient, with 300mb jet streak upwards of
120 kts. The strong cold front has pushed southward of the Ozarks
this morning, with strong surface anticyclone tracking southward
from the eastern Dakotas and into Iowa this morning. While the cold
air is already pouring into northern Missouri this morning, the
surface anticyclone will continue to move toward the Missouri River
Valley, pushing much drier air in. Current dewpoints in Iowa have
been a few degrees below zero. Most locations in our forecast today
at some point should see single digit dewpoints. This push of drier
air should help to eliminate the stratiform cloud deck noted on GOES
Night time imagery as 08z. For the remainder of the day, the trough
axis exits the Four Corners and picks up in propagation eastward,
which will send a vort maxima into the southern Plains and
eventually toward the lower Mississippi River Valley. The strongest
portion of this will miss the forecast area, and allows the center
of the surface anticyclone to pass through unimpeded.

Friday, H5 short-wave disturbance moves across the Rockies and
toward the Central Plains. For most of the day, this will keep our
mid-level flow mostly zonal. The stronger dCVA and surface
cyclogenesis process will be favored somewhere in the southern
Plains. While this is happening, the strong surface anticyclone gets
pushed eastward into the Southern Great Lakes Region. The
anticyclone also gets a push from another vort max that drops south
from the Hudson Bay system that provides strong westerly flow from
the western Great Lakes to the Southern Great Lakes Region. As that
high pressure exits and a low pressure begins to develop in the
southern Plains, lower tropospheric flow turns southerly late Friday
morning through afternoon, and pushes a warmer airmass toward the
lower Missouri River Valley along with a push of moisture. The WAA
appears to miss portions of north-central and northeastern Missouri,
were temperatures will likely stay in the mid 30s. Draw a line from
Sedalia, MO to St. Joseph, MO, areas southwest of this line
including Kansas City are expected to jump back into the lower and
even perhaps mid 40s. NBM members are fairly confident in this, as
inner-quartile spread is only a few degrees. Most guidance remains
dry for Friday, thus will maintain a dry forecast. If there is
stronger isentropic ascent that occurs, perhaps some light rain
could become possible. Current depiction though is for increased
boundary layer moisture, but dry column above that, which is likely
why current model output has no QPF for Friday.

Saturday through Sunday, exact details get fuzzy. Fairly high
confidence in notable mid-level troughing moving through the Central
CONUS. WPC Cluster Analysis shows consistent 500mb troughing, with
no noticeable difference between its Grand Ensemble Mean. Everything
though lies in where the surface cyclone tracks, and with which vort
maxima drives most of the mid-level support. There will be the
developing cyclone in the southern Plains that helped to bring
warmer and perhaps more moist air to around Interstate 70 by late
Friday into early Saturday. Some guidance and ensemble members are
pushing that cyclone into the Gulf, while others try to bring it
north. Some solutions are depicting a strong H5 vort max providing
robust dCVA in the Front Range and High Plains of KS/NE, with
surface pressure falls than extending eastward. How this evolves
will affect how far any kind of warm front feature moves northward,
which also determines how much moisture returns to the area. Then
ultimately for Saturday afternoon through Sunday morning, will
determine where the best forcing occurs. Amongst the deterministic
solutions, the GFS remains an outlier with respect to QPF and
snow totals for northern Missouri. The GFS places most of north-
central and central Missouri in a strong deformation zone, with a
few areas of enhanced FGEN, as well lower EPV suggesting some CSI
release. As a result, this is outputting a few inches of snow from
north-central Missouri to central Missouri. Will note this is
substantially less than Tuesday`s Nights 00z run. The deterministic
ECMWF takes the center of the surface cyclone through northern
Missouri, which places Iowa and areas closer to Interstate 80 in a
more favorable zone for deformation zone, potential FGEN processes,
and warm conveyor belt moisture transport. This struggles to produce
anything more than 1 inch of snowfall for northern Missouri. The NAM
is more similar to the ECMWF with respect to track, but appears to
be taking the moisture further westward. But this solution also keep
snow totals under one inch for most of northern Missouri. GEFS
members are not a robust as its deterministic counter part. While it
does shift probabilities for at least one inch or more a bit further
southward, overall GEFS mean values for snow across northern and
central Missouri are right around one inch. Other ensemble suites,
including the members of the NBM, concentrate better probabilities
closer to the Interstate 80 corridor across Iowa. With the GFS still
being in outlier, and the NBM seemingly matching well with other
global scale ensemble suites, have not greatly deviated from NBM for
the Saturday into Sunday forecast, which generally does not produce
much more than an inch of snowfall. There is some low end potential
for light freezing rain or some other kind of mixtures as the
cyclone moves through, and some model soundings show rich boundary
layer moisture but no ice introduction with a drier DGZ. A strong
surface anticyclone is depicted dropping out of the Northern Plains
immediately behind this system, therefore showing a favorable setup
for the column and surface to cool fairly rapidly. This would result
mainly in snow for far northern Missouri, and rain-snow mix for
central Missouri, with a very narrow window for some type of
freezing rain or drizzle. Even then, with the Friday warm up,
surface temperatures may remain above freezing during the onset of
precipitation, and appears more likely that by the time surface
temperatures reach freezing late Saturday Night, there would be
enough ice introduction to transition to all snow. The potential for
mixed precipitation depends largely on the track and where that warm
front ends up.

Strong northwesterly flow will eventually chase out this system
eastward by late Sunday, with another strong anticyclone pushing a
dry polar air mass into the region. Flow appears to remain
progressive though, which could bring another system by the middle
of the week. Depending on the magnitude of this, there is some
potential for strong WAA to push temperatures back into the 50s for
areas along and south of Interstate 70. The pattern overall is not
being resolved consistently amongst model guidance though. Inner-
quartile spread for multiple parameters are still very wide for the
end of the forecast period through the middle of next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 516 AM CST Thu Dec 4 2025

High pressure will continue to move southward toward area, and
has already starting clearing out the overcast VFR cloud cover.
Surface winds will veer throughout the day as the high pressure
passes through, but generally should be under 12kts. VFR
conditions expected through the period.

&&

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

&&

$$

DISCUSSION...Krull
AVIATION...Krull