St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

533
FXUS63 KEAX 250246
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
846 PM CST Wed Dec 24 2025

.KEY MESSAGES...

- Another Night and Morning of Dense Fog

- Above Normal Temperatures; Fog and Low Clouds May Prevent Daily
  Records

- Winter Like Conditions Return Sunday

&&

.DISCUSSION...
Issued at 236 PM CST Wed Dec 24 2025

Broad ridge is still prominent across the Central CONUS this
afternoon and will continue to be through Friday. PV anomaly over
the Pacific has shifted further eastward, and H5 trough is starting
to approach the coast of California. This is sending several
localized vort maxima across the Intermountain West and into the
Front Range. The persistent nudges and shots of dCVA has been enough
to maintain a surface low over the Central Plains and keeping lower
tropospheric flow southerly, along with plenty of moisture transport
from the Gulf. Fog and stratus over the past couple of days resulted
in stronger differential heating across the forecast area, so along
with periods of weak and strong WAA, have placed a boundary which so
far today has moved northward as warm front to around Interstate 70.
It took a while but finally started to see some breaks in the cloud
cover. However, after sunset tonight, the low over the Plains stalls
and eastward surface trough does as well, resulting in weaker
pressure gradient in the Lower Missouri River Valley. With plenty of
moisture still in place and perhaps some pooling along the thermal
boundary, this is setting up another favorable scenario for fog,
that could start as early as 03z-04z this evening and continue into
Thursday morning. HREF probabilities have been fairly high for dense
fog between Hwy. 50 and Hwy. 36, especially during the pre-dawn
hours of Thursday. Given this strong signal in the probabilistic
fields amongst ensemble members, persistence, and little actual
change to the pattern, have issued a Dense Fog Advisory this evening
for most of the area. Counties further south of Hwy. 50 are
currently not included, and counties that border the Iowa state line
have also been excluded. However if the warm front does move further
north and results in better moisture transport through the evening,
dense fog may find its way into far northern Missouri. There is also
potential for drizzle along the warm front where there may be a
little extra lift for a few hours late tonight, and the first
kilometer from the surface upward completely saturated. Drizzle
occurrence may delay the onset of fog in some locations, but by
Thursday morning should come to an end to allow fog to develop.

Unsure how long the fog will last into Thursday afternoon, as these
past few fog events have been a hybrid of both advection, and
radiational cooling, processes. The amount of upper-level cloud
cover may also play in role in how efficient mixing can start to
erode the fog and low-level stratus. This will also have important
implications for high temperatures on Thursday. WAA will still keep
conditions well above normal for this time of year, but an
increasing signal for lingering cloud cover especially along the
Interstate 70 corridor and northward may keep things below daily
records. This may largely depend on the movement of the boundary.
Areas south of Hwy. 50 perhaps could see some clearing if the front
pushes well northward, and if the low deepens could help increase
wind. This is likely the area to reach the 70 degree mark if any
points in our forecast area are able to achieve it. But compared to
what model guidance was projecting before this pattern setup here,
it is notably cooler. Friday morning, the ridge axis deamplifies as
more vorticity advection occurs over the Intermountain West, and
works to deepen the surface cyclone. Southerly flow strengthens
again and pushes the warm front toward the Iowa state line, or,
perhaps even further into Iowa. This will provide another warm day.
This continues into Saturday. The main H85 thermal ridge axis will
pass through Saturday, maintaining temperatures into the mid 60s,
though far northern Missouri may only see the upper 50s. A dry
airmass will likely move through early Saturday morning, but cooler
temperatures are not progged to occur with a subtle boundary moving
through. Clearing skies and returning southerly flow with another
wave moving through will keep conditions warm.

Sunday, deeper H5 trough travels into the Front Rockies, and pushes
the the low pressure toward the Great Lakes Region, with stronger
lobe of vorticity moving toward the upper Midwest. A strong surface
anticyclone trails this feature dropping southeastward from Canada,
bringing a strong polar airmass into the CONUS. This strong cold
front moves through the lat afternoon hours, and will drop
temperatures to below late December normal values. Ensemble guidance
has pulled some low end probabilities for rain and rain-snow mix into
our eastern counties, but currently does not depict much in the way
of accumulation. The main story on Sunday will be the gusty
northwesterly winds, along with major temperature swing. This will
lead to cooler conditions through next week. We will need to monitor
this system, if that H5 trough digs further south, we could see more
surface convergence that could bring more precipitation late Sunday.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 543 PM CST Wed Dec 24 2025

Dense fog is trying to push across northeast and north central
MO in places like IRK with some jumping around between 3/4 and
1/4 mile visibilities. Also seeing some increasing areas like
STJ TAF sites periodic with 1/4sm criteria. May have to update
the Dense fog advisory as conditions may star before 03z.
Expect IFR conditions to continue as the dense fog spreads back
in across much of the area after between 00 and 03z. This will
remain through 15z on Christmas (Thursday) morning. It will
gradually break as fog and dense fog (1/4 mile conditions) will
begin to clear after 18z tomorrow.

&&

.CLIMATE...
Issued at 157 AM CST Tue Dec 23 2025

Record High Temperatures:

December 24:
KMCI: 72/2021
KSTJ: 69/2021

December 25:
KMCI: 67/1922
KSTJ: 65/2019

December 26:
KMCI: 66/2008
KSTJ: 65/2008

Record High Minimum Temperatures:

December 25:
KMCI: 53/1936
KSTJ: 51/1936

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Dense Fog Advisory until 10 AM CST Thursday for MOZ001>008-
     011>017-020>025-028>033-037>040-043>046.
KS...Dense Fog Advisory until 10 AM CST Thursday for KSZ025-057-
     102>105.

&&

$$

DISCUSSION...WFO EAX
AVIATION...WFO EAX
CLIMATE...CMS