St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

150
FXUS63 KEAX 170822
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
322 AM CDT Wed Jun 17 2026

.KEY MESSAGES...

- Severe thunderstorms are expected to develop this afternoon
  along a cold front moving southeastward through the region.
  The best chances for storms are south of a line from Kansas
  City to Kirksville. Large hail, damaging winds, tornadoes, and
  heavy rainfall are all potential hazards from these storms.

- Southwest winds of 15 to 30 mph with occasional gusts
  exceeding 45 mph are expected this morning across the area.

- Heat indices approaching/exceeding 100 degrees are forecast
  this afternoon, especially south of I-70.

- Showers and a few thunderstorms are forecast again across
  west-central and central Missouri on Thursday. Severe weather
  is not expected.

- A strong storm system will move through the region this
  weekend, bringing another round of severe weather and heavy
  rainfall.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 233 AM CDT Wed Jun 17 2026

A northwest-flow regime is in place across the central U.S. this
morning. A vigorous shortwave trough is progressing
southeastward from the northern Rockies, with convection
developing in advance across the Dakotas into Iowa and
Minnesota. With time, this convection will organize and
intensify in Iowa. Convection-allowing models have suggested the
southern edge of these storms will clip far northern Missouri
around/after daybreak. Though we are expecting the most intense
convection to remain north of the Iowa/Missouri border,
certainly cannot rule out thunderstorms roughly north of U.S.
136 this morning, and have raised PoPs in these areas
accordingly. Should the storms sufficiently organize, a severe
storm cannot be ruled out given the rapidly improving
instability and shear. Any such storms would move east of the
forecast area by late morning.

A more confident aspect of this morning`s forecast is the
strong/gusty winds expected across the area. An intense (60+ kt)
low-level jet will traverse the region during the morning as it
veers and translates eastward in advance of the aforementioned
shortwave trough. Sufficient boundary-layer mixing of these
strong winds aloft will occur near/after sunrise, leading to a
period of unusually gusty non-thunderstorm winds for this time
of year. Peak wind gusts exceeding 45 mph are probable
(probabilities greater than 50 percent) in most of the forecast
area. The winds should gradually subside this afternoon, as the
low-level jet progresses well east of the area.

Meanwhile, a cold front trailing the Upper Midwest surface low
will surge southeastward through the central Plains this
afternoon. Though large-scale ascent will be fairly weak in the
wake of the shortwave trough racing eastward toward the Great
Lakes, the strong warm-sector southwest winds and the decently
strong northwest winds upstream of the cold front will supply
strong frontal convergence in a rapidly destabilizing
environment this afternoon. Convection is expected to erupt
readily along the front by mid-to-late afternoon (near/after 3
pm), and may do so from east to west, becoming more isolated
farther west. Shear profiles are unusually strong for this time
of year (0-6 km bulk wind difference exceeding 60 kt; 0-1 km SRH
near or higher than 150 J/kg), with MLCAPE of 2000-4000 J/kg by
late afternoon in the preconvective warm sector. This parameter
space, combined with at least some orthogonal component of the
shear vector relative to the initiating boundary, suggests
supercell storms are favored this afternoon/evening.
Kinematic/thermodynamic profiles are favorable for all severe
hazards, including torrential rainfall (PWs 1.75+ inches).

The main question will be when and where storms develop, with
most CAMs suggesting this will generally be near or just south
of a line from Kansas City to Kirksville around/after 3 pm.
Most areas to the north/northwest of this line will see little
or no precipitation this afternoon/evening, but areas in advance
of the storms may see locally high amounts given the
substantial moisture in place. An isolated instance of flash
flooding is possible (around a 20 percent chance). More likely
is large to very large hail and damaging winds offered by the
discrete or semi-discrete storms. The tornado potential
certainly exists as well given the strong wind/shear profile in
place.

Speaking of the substantial moisture, another potential hazard
posed today is relatively high heat indices before convection
initiates, with forecast highs soaring into the 90s and heat
indices approaching/exceeding 100 degrees. Heat indices may
flirt with advisory criteria, particularly south of the metro,
but the duration of these high heat indices combined with
uncertainty associated with developing convection preclude
issuance of a heat advisory at this time.

The front will slow its southward progress tonight, perhaps
lingering in our far south for much of the evening/overnight,
before finally shifting farther south into the Ozarks late.
However, models are hinting at a reinforcing vorticity maximum
moving southeastward into the central Plains Thursday morning.
CAMs are signaling a round of showers and at least isolated
storms during the day Thursday, particularly in the southern CWA
in closer proximity to the stalling front. Have increased PoPs
for Thursday south of I-70, and would not be surprised if at
least a few showers occur farther north as well. Think the
better chances of severe weather will be south of the forecast
area, though, in closer proximity to the front and greater
instability to its south.

After today`s hot weather, Thursday`s high temperatures will
return to more pleasant upper 70s and lower 80s. Lows on
Thursday night may drop into the 50s for most locations outside
of the KC metro.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 233 AM CDT Wed Jun 17 2026

Another quick-moving shortwave trough should progress
southeastward through the central U.S. on Friday, but this
system should be more moisture-starved and farther north of
Kansas/Missouri. Expecting Friday to be dry and somewhat warmer,
with highs in the mid to upper 80s. Friday night and Saturday,
the pattern begins to change, with a potent vorticity maximum
ejecting eastward from the western U.S. during this period. This
should lead to lee cyclogenesis in vicinity of eastern Colorado
or western Kansas on Saturday. The surface low will probably be
quite strong, given favorable large-scale ascent downstream of
the attendant vort max collocated with upper divergence from a
rapidly intensifying anticyclonic upper-level jet streak. During
this 24-hour period, a lengthy southerly fetch straight from the
Gulf should result in substantial moisture advection. Anomalous
PWs (nearing 2 inches by Saturday night) in a sufficiently
unstable environment will lead to efficient precipitation
production with widespread convection that develops near/east of
the advancing surface low. The GFS/CMC/ECMWF ensembles are
quite consistent in this general evolution, but vary
considerably with timing and geographical placement (e.g., ECMWF
much farther north than the GFS/CMC; CMC much slower than GFS).

Despite these uncertainties, confidence is increasing that the
weekend will be an active period for our region, with both
severe weather and flash flooding as potential hazards from the
approaching system. Given the number of activities going on
across the area this weekend, this system bears monitoring for
its potential significant societal impacts. The flooding
potential is especially worrisome given the still-saturated
soils across the area (particularly northern Missouri) and the
highly anomalous tropospheric thermodynamic profiles. Stay tuned
to the latest forecasts as forecast variability gradually
lowers.

A respite of dry weather is expected early next week, but
longer-range models suggest another active period may follow, as
a deep longwave trough develops in the central U.S. late in the
month of June.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1058 PM CDT Tue Jun 16 2026

Winds gradually accelerate through the overnight with borderline
LLWS possible before momentum transfer brings southerly winds
to the surface. Winds really accelerate after sunrise as
diurnal mixing begins. Wind gusts of 30-40 knots are
anticipated with intermittent higher gusts possible. A cold
front moves through the area midday to early afternoon shifting
winds northwesterly. RA/TSRA is expected to develop along the
front; however, guidance does favor these storms forming east of
the terminals. Some isolated SHRA with VCTS is possible if the
area of convective initiation shifts. Winds dissipate after
sunset.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory from 7 AM this morning to 1 PM CDT this
     afternoon for MOZ001>006-011>015-020-021-028-029.
     Wind Advisory from 7 AM this morning to 3 PM CDT this
     afternoon for MOZ007-008-016-017-022>025-030>033-037>040-
     043>046-053-054.
KS...Wind Advisory from 7 AM this morning to 1 PM CDT this
     afternoon for KSZ025-102>104.
     Wind Advisory from 7 AM this morning to 3 PM CDT this
     afternoon for KSZ057-060-105.

&&

$$

SHORT TERM...CMS
LONG TERM...CMS
AVIATION...Pesel