St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

065
FXUS63 KEAX 221024
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
424 AM CST Thu Jan 22 2026

.KEY MESSAGES...

- One more afternoon of near normal temperatures, then Arctic air

- Further Northward Trend for Snowfall This Weekend, Northern Edge
  Still Uncertain

- Bitter Cold Wind Chills Most of the Weekend

&&

.DISCUSSION...
Issued at 423 AM CST Thu Jan 22 2026

Surface anticyclone is over the area this morning, and will be
pushed southeastward with brisk north-northwestelry mid-level flow.
Should see plenty of sunshine today, with only a few passing clouds.
With surface high moving southeastward, and first shot of dCVA into
the southwestern CONUS, expecting southwesterly flow by this
afternoon that will then gradually veer through the evening. This
should boost temperatures back into the lower 40s for most of the
forecast area, with upper 30s toward the Kirksville region. Strong
surface anticyclone over western Canada pushes the Arctic Airmass
southeastward as a mid-level vort max from the Canadian closed-low
system pushes stronger northwesterly flow into the Central CONUS.
The PV anomaly over the Pacific shifts eastward, promoting more
troughing over the southwest CONUS where multiple short-wave
perturbations will start to emanate from.

Friday afternoon, the strong surface anticyclone continues its push
into the Central CONUS as well as pushing the strong Arctic Cold
Front through the area. Several lobes of mid-level vort maxima start
ejecting eastward toward the southern Plains and lower Mississippi
River Valley and will promote surface pressure falls in the
southwestern CONUS. This will eventually develop a stronger surface
cyclone, but will stay several hundred miles south of the forecast
area. The open wave between 850mb to 700 MB should result in
southerly flow late Friday that starts to increase moisture in this
layer. However, the approaching surface anticyclone from the
northwest and the Arctic airmass will starve the boundary layer of
most of its moisture. From here, is where the divergence in
deterministic model solutions begins. The 00z GFS is now struggling
to phase the H5 trough axis from the northern wave with the axis
from the southern trough axis, which is creating multiple periods of
enhanced dCVA across the Central CONUS. Based on subjective
analysis, there are three notable axes at H5 with enhanced
vorticity, meaning three areas of distinct lift. The southern most
trough axis in the GFS solution though is not digging as far south
into Mexico as the 00z cycles form the previous night had it. This
actually tracks the surface cyclone closer the coast through the
Gulf. The ECMWF on the other hand only has two H5 trough axes,
making the northern one slightly deeper and slightly wider in its
influence with its dCVA, though perhaps not as strong. The ECMWF
also tracks its cyclone center directly along the Gulf Coast from
Texas into Louisiana. This has access to a bit more moisture, and
continues to advect better moisture northward and at a faster speed.
The change in the ECMWF is that it brings the surface anticyclone a
bit further south, and slightly stronger, closer to what the GFS has
been trying to do it with. As a result, this provides a slight delay
to increased boundary layer moisture, but, this is still faster than
the GFS. This is why the ECMWF likely had a subtle decrease it is
progged snowfall totals. Then there is the NAM, which is handling
the H5 pattern differently than the GFS and ECMWF, and that vort max
quickly gets absorbed northward into the northern trough axis. But
the surface features track more closely with that of the ECMWF, and
this too brings in boundary layer moisture and starts snowfall
earlier than the GFS. This is the first source of uncertainty, is
how quickly snowfall starts. Current forecast has snow starting late
Friday Night and overnight. However, if a GFS boundary layer
moisture profile (that is lack of moisture) holds, accumulating snow
may hold off until early Saturday morning. Holding off on snow by 6
hours would result in the lower end of expected snowfall ranges
being realized. The second source of uncertainty, is how far north
does sufficient moisture actually reach. Looking at postage stamp
plots of all ensemble members, there are some that take QPF all the
way to Interstate 80 in Iowa, and there are some that have the
northern suburbs of KC dry while the southern suburbs get high QPF.
Most of the forcing for our snow will be driven from 850mb and
upward from the passing vort maxima, which means it has to be enough
to overcome the surface anticyclone. There is some signal in both
GFS and NAM that areas from Linn County KS to Henry County MO may
see some lower EPV and weak FGEN processes, tied closed to where the
strongest Q-vector convergence is at 700mb and 500mb. It is not a
slam dunk though for CSI release. The DGZ will be fairly deep
though. Although the raw lift values are not as impressive as they
are over the Ozarks region, the lift will still be there to result
in snow ratios of 17:1 or even 18:1. But lack of any strong
baroclinic gradient will largely prevent these typical dendrite
enhancements from being realized. Taking a dive in to ensemble
output, GEFS mean is between 2-3 inches for I-70 to Hwy. 36, and 4-6
inches southward. The GEFS remains more moist than its deterministic
counterpart. Other ensemble suite means still try to depict 3-5
inches right around Interstate 70, and then higher as you move
toward the Ozarks. However, these solutions with higher end amounts
are starting the snowfall fairly early, and at times when we may
still have a very dry boundary layer. Overall ensemble probabilities
for exceeding 3 inches of snowfall are high, about 60 percent as far
north as Hwy. 36, and with a threshold of 5 inches just a tad under
50 percent. Note these percentages are much higher for areas well
south of Hwy. 50. For some individual ensemble members and their
associated probability of exceedance maps, have just under a 50
percent chance for 5 inches of snowfall (criteria for winter storm
warning in our area). But, these all assume a 10:1 ratio, so with
higher ratios, their probabilities for 5 inches of snow given the
same QPF is actually above 50 percent. There are some outliers that
continue to skew the distribution quite a bit, as some locations
have even their 75th percentile snow values near 10 inches south of
Interstate 70. While that is not out of the realm, that is going to
take a lot to overcome the dry air that will be in place. But,
describes the high degree of uncertainty we are still facing with
this snowfall forecast. Given that probabilities for 5 inches of
snowfall are starting to sneak above 50 percent for areas around
Interstate 70, have expanded the Winter Storm Watch northward. The
lower end amounts are below winter storm criteria, but the upper end
potential is solidly in it. Given the potential impacts with the
single digit air temperatures, along with neighboring offices have
pulled that watch northward. Some of these counties may only end up
with advisory level snow, but for now the watch will help describe
the upper end potential if that moisture surge is able to occur. The
final push of CVA exits the area late Sunday, but most of the
forcing for snow should be well eastward by Sunday afternoon. A
fresh snow pack may lead to very cold temperatures, and bitter wind
chills that continue into Monday of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1005 PM CST Wed Jan 21 2026

For the 06z TAF package, winds will become light and variable as
high pressure briefly become centered over the area. As the high
translates east, winds will pick up from the W-NW during the
afternoon around 5-10 kts. After 00z Friday, an Arctic cold
front will being to move through the region, and winds will
shift to the N and increase, with sustained wind around 8-12
kts.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Cold Weather Advisory from midnight tonight to noon CST
     Saturday for MOZ001-011>014-020>025-031>033.
     Winter Storm Watch from Friday evening through late Saturday
     night for MOZ028>031-037>040-043>046-053-054.
     Cold Weather Advisory from midnight Friday night to noon CST
     Saturday for MOZ028>030-037>040-043>046-053-054.
     Extreme Cold Warning from midnight tonight to noon CST Friday
     for MOZ002>008-015>017.
     Cold Weather Advisory from noon Friday to noon CST Saturday
     for MOZ002>008-015>017.
KS...Cold Weather Advisory from midnight tonight to noon CST
     Saturday for KSZ025-102.
     Winter Storm Watch from Friday evening through late Saturday
     night for KSZ025-057-060-103>105.
     Cold Weather Advisory from midnight Friday night to noon CST
     Saturday for KSZ057-060-103>105.

&&

$$

DISCUSSION...Krull
AVIATION...Snyder