St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

381
FXUS63 KEAX 081157
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
657 AM CDT Mon Jun 8 2026

.KEY MESSAGES...

- Scattered showers and isolated thunderstorms continue
  overnight. Additional storm development is expected across
  southwest MO which could extend into west central MO along the
  HWY 18 corridor.

- Hazardous heat is expected this week. Heat indices reach the
  90s to upper 90s across west central MO today. Heat index
  values above 100F are expected Tuesday and Wednesday.

- Showers and thunderstorms return as early as late this
  afternoon into the evening with more widespread thunderstorms
  possible overnight. Heavy rain, flooding, damaging winds, and
  hail are the primary concerns.

- Additional rounds of showers and storms are anticipated
  through the week, mainly during the overnight periods.

&&

.UPDATE...
Issued at 550 AM CDT Mon Jun 8 2026

As anticipated, uncertainty in shortwave CVA, the northward
placement of the warm frontogenesis, progression of the synoptic
ridge is resulting in the a bit of a shift in timing and location of
storms. Recent model guidance now poses the potential for a more
southern location for isolated storm development this afternoon as
well as a more southern track of a potential overnight thunderstorm
complex. The forecast remains consistent with rapid warm
frontogenesis developing later this afternoon and evening, but where
this develops will be a critical factor in where storms line up.
This location of the front will also play a critical role in where
the anticipated nocturnal MCS may track. Minus the manipulation of
the larger synoptic pattern, the MCS will likely track along a
gradient of instability or a thermal bounday (such as where the
previously mentioned warm front may be). Recent guidance has been
moving this boundary and storms southward from the previous scenario
across far northern MO further south toward the I-70 corridor.
Multiple CAM guidance both deterministic and ensembles so the
potential for this storm complex to track as far south as the I-70
corridor with some suggestion even further southward propagation.
Expected impacts remain unchanged with heavy rainfall resurrecting
flooding concerns as well as the chances for damaging winds and hail.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 222 AM CDT Mon Jun 8 2026

A substantial trough is moving through the region keeping scattered
showers through the night. The most substantial convection is
expected across eastern MO. Widespread ascent combined with a
saturated environment and persistent moisture transport leading to
widespread showers some including heavy rainfall. This has kept
chances for flooding around, especially near creeks and streams
across central MO.

This first wave continues to push off to the northeast dragging the
showers with it. However, another lee trough is developing across
eastern CO. As this trough deepens it focuses the nocturnal LLJ
across OK dumping into SW MO. This reinvigorates showers and
thunderstorms across the I-44 corridor potentially extending
northward into Linn (KS) and Bates counties. During the daytime
hours a combination of upper level shortwave ridging and surface
divergence due to the interactions of Sunday night`s trough to the
east and the shortwave ridge result in the daytime hours being
mostly dry with shower activity being rather limited. The advection
of warm air and moisture continues into the region keeping warm and
generally uncomfortable conditions around. Heat indicies south of
the MO River reach the mid to upper 90s with 100F heat indices
possible near the HWY 18 corridor. Meanwhile NW flow aloft keeps
heat indices a little cooler across the NE portions of the area.
That said, dew points in the 70s will make the air feel quite thick
and unpleasant.

Cyclogenesis continues across southern KS. The warm air and moisture
advection mentioned previously feeds unstable air across the region.
Multiple shortwave aloft are expected to break the cap initiating
convection later this evening across central KS. Surface divergence
thanks to the interactions of a trough to the east and the low to the
west keeps activity in our area fairly benign with only isolated to
scattered showers and storms through the day. The eastern trough and
complimentary ridge are expected to slide eastward towards sunset.
This facilitates fairly rapid warm frontogenesis across the area
during the evening. This will try to act as a focus for convective
development; however, CAM guidance does show some residual capping
present that will resist the development of showers and storms.
Upper level high pressure building up from the south also acts as a
limiter for convection as it looks to divert passing upper level
shortwave CVA to the north and east. There is some notable
uncertainty as most model guidance does try to produce an MCS which
is expected to move along the I-80 corridor overnight Monday into
Tuesday. CAMs favor this MCS staying north of our CWA; however,
legacy deterministic models pose the potential for the storm complex
to extend into northern MO bringing even more rainfall to the
region. The main causes being the location of the exit region of the
expected nocturnal LLJ as well as the northward push of the upper
level ridge. If either of these underperform expectations, it opens
up the door for more potentially heavy rainfall.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 222 AM CDT Mon Jun 8 2026

The cut off low will be pulling away to the northeast toward the
Great Lakes Tuesday and high pressure will be re-established across
the region. The riding aloft will slowly slide east as a trough
descends into the Northern Plains then swings northeast back through
the Great Lakes. What this means for KS and MO is that, we will be
trapped between the ridge in the east and a trough to the northwest.
Multiple shortwave troughs are expected to move through the flow,
which could bring some PVA aloft. Wednesday evening into Thursday
looks to be best potential chance for rain (60-70% at it peak
Wednesday evening). With some PVA aloft (shortwave) and a mid level
low develop to the west of the Rockies, there is still some
uncertainty in timing. This is especially true when you look at
the sfc cold front timing. Given the high temperatures,
dewpoints and ongoing WAA there will be a potential for some
strong to severe storms.

As the cold front moves through, the strong WAA should win out stall
the frontal boundary and move it back northward as a warm front
which could bring additional rain/storm chances through Friday
into Saturday. This timing with the sfc frontal boundaries does
line up with another shortwave aloft. There is still a lot of
variability in the strength of the shortwave and timing of the
sfc features so will have to keep an eye on this moving forward.


Otherwise the main message becomes the hot and humid conditions
expected from roughly Tuesday through Thursday. Temperatures in the
upper 80s to low 90s with dewpoints in the mid to upper 70s. Now if
the cold front passes late Wednesday, then temperatures and
dewpoints will be cooler Thursday. For Tuesday specifically, heat
indicies are expected to climb to around 105 degrees for the Metro
and counties south of the Missouri River. With high confidence in
hitting those heat indicies a heat advisory has been issued for
those areas Tuesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1232 AM CDT Mon Jun 8 2026

VFR to IFR conditions are expected through the period. The IFR
ceilings around 300 to 1000 feet this morning are expected to
gradually rise and scatter out late this morning into this
afternoon. VFR conditions will return as clouds scatter out.
Later this afternoon/evening clouds will filter back in with VFR
to MVFR ceilings expected. There is a chance for rain and
thunderstorms to develop again late this afternoon into tonight.
There is uncertainty on if the exact timing and duration of
storms so rain was handled with PROB30s. If rain/storms develop
they are expected to be scattered. Heading into Tuesday, drier
conditions are expected with VFR ceilings.

Southwest winds this morning will gradually become southerly
then southwesterly by tonight. There is a small period where
winds could go variable  for an hour or two Tuesday morning
around 12Z then south winds return and are expected to become
breezy Tuesday.

&&


.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory from noon to 10 PM CDT Tuesday for MOZ028-029-
     037>040-043>046-053-054.
     Flood Watch until 1 PM CDT this afternoon for MOZ006>008-
     015>017-023>025-030>033-038>040-043>046-053-054.
KS...Heat Advisory from noon to 10 PM CDT Tuesday for KSZ057-060-
     103>105.
     Flood Watch until 1 PM CDT this afternoon for KSZ060.

&&

$$

SHORT TERM...Pesel
LONG TERM...Patterson
AVIATION...Patterson
UPDATE...Pesel