St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

062
FXUS63 KEAX 201131
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
631 AM CDT Thu Aug 20 2026

.KEY MESSAGES...

- Areas of dense fog this morning will lift within a few hours of
  sunrise.

- Showers and storms return to the forecast Friday night -
  Saturday morning and again Sunday night - Monday morning. Best
  chance for strong to possibly severe storms looks like Friday
  night - early Saturday morning.

- Seasonal temperatures likely through the forecast with highs
  generally in the middle to upper 80s and lows in the middle to
  upper 60s.

&&

.DISCUSSION...
Issued at 219 AM CDT Thu Aug 20 2026

High pressure is sliding southward into the area with winds becoming
light. With all the rain the area has received lately, the boundary
layer will easily become saturated and with light/ calm winds, areas
of dense fog are likely. As of 02Z, several typical several sites
are reporting visibilities as low as a 1/2 mile. Nighttime
microphysics imagery is also showing signals of fog in northwestern
Missouri from Maryville to St Joe westward to the Missouri River.
Further east there has been a mix of low stratus (which could build
down to the surface with time) and mid-level clouds. HREF and SREF
visibility probabilities show 50-80% probabilities of visibility
less than 1 mile from northwestern to central Missouri and
southward. Will go with a dense fog advisory for the highest
probability areas and where observational data shows fog. This would
be roughly along and north of Highway 36 as a starting point and
will monitor for development further south for a possible expansion.

Focus then shifts to a couple of chances for showers and storms. The
pattern is defined by upper ridging to our west and broad troughing
to our east, putting the area into northwest flow. The area will
also be under the upper jet and as a result we`ll see several
shortwave troughs move across the area with favorable jet dynamics
evident. There is a leading shortwave that moves through the area
Friday afternoon. This has the potential to develop some storms but
the timing doesn`t look favorable for with this wave as its east of
of us by peak heating. But it will need to be watched given
propensity for northwest flow to outperform expectations. The better
chance for precipitation looks to be Friday night into Saturday
morning. Another embedded wave, potentially an internal PV anomaly
from upstream convection, tracks southeastward along the nose of an
upper-level jet-streak. While instability doesn`t look to be all
that high, there may still be anywhere from 500 to 1500 J/kg of
MUCAPE. The strong northwesterly flow favors 40-50kts of deep-layer
shear. This will lead to the potential for strong to severe storms
Friday night-early Saturday morning. There is another potential
round Sunday night into Monday morning. Another shortwave or
internal PV anomaly moves southeast Instability looks very limited
during this time frame so the potential for anything strong to
severe looks quite a bit lower.

Overall, with the upper ridging to our west, temperatures look
fairly close to normal for this time of year with highs generally in
the middle 80s, with some variability, and lows in the middle to
upper 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 631 AM CDT Thu Aug 20 2026

Areas of dense fog and low stratus (with conditions ranging from
VLIFR to IFR) have developed and/or built into the area. The
fog should linger for several more hours, lifting into a low
stratus between 14 and 15Z, with that stratus lingering through
17 to 18Z before VFR conditions are expected. Winds will be
light through the forecast.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Dense Fog Advisory until 10 AM CDT this morning for MOZ001>008-
     011>017-020>025-028>032-038-039-044>046-054.
KS...Dense Fog Advisory until 10 AM CDT this morning for KSZ025-
     102>104.

&&

$$

DISCUSSION...CDB
SHORT TERM...
LONG TERM...
AVIATION...CDB