St. Joseph, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

500
FXUS63 KEAX 162326
AFDEAX

Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
626 PM CDT Sat May 16 2026

...Updated 00z Aviation...

.KEY MESSAGES...

* Strong to severe storms possible (50-70%) late this afternoon and
  evening, primarily across northern Missouri. All hazards are
  possible, but the greatest threats are damaging winds and heavy
  rainfall.

* Warm and windy conditions Sunday before another chance of storms
  later in the evening/overnight, mainly across northern Missouri
  again. The primary hazard would be hail.

* Greatest chance for severe weather arrives Monday evening into
  the overnight hours. All severe hazards will be possible.

&&

.DISCUSSION...
Issued at 342 PM CDT Sat May 16 2026

Earlier this morning, scattered showers and storms driven by the low-
level jet spread across the southern half of the CWA. A residual
outflow boundary from overnight convection lifting north caused
additional storms to form near the US-36 corridor. These storms
persisted for a couple of hours before decaying in tandem with the
low-level jet. CAMs were unable to latch onto the morning
convection, thus limiting trust in guidance for the remainder of the
immediate forecast period and leading to several questions about how
the evening will unfold.

In the wake of morning precipitation and storms, clear sky
conditions  largely took hold along and west of US-63. This, along
with southerly surface flow, led to destabilization across the CWA.
Mesoanalysis indicates around 1000-1500 J/kg of SBCAPE was ushered
into the region between 15Z and 18Z. As of 20Z, SBCAPE across
Missouri has increased to 3000-4000 J/kg. ACARS soundings have shown
this trend, most recently with SBCAPE ~3000 J/kg and falling CIN.
With increased instability, sporadic cumulus development was noted
across the region early this afternoon. The latest analysis of
surface observations indicate that a stalled boundary continues to
roughly bisect Iowa in a northwest/southeast manner. This boundary
will be the primary lifting mechanism as we head into the late
afternoon and early evening. Importantly, there has been a southward
trend in the boundary`s trajectory this evening, ultimately
increasing the likelihood of convection for the northern portions of
Missouri as well as northeast Kansas. Satellite imagery remains
indicative of some sort of mesoscale boundary within the US-36
corridor that could allow for convection to light up as a weak
shortwave trough propagates eastward and ahead of the larger,
synoptic scale boundary currently sitting in Iowa. As such, isolated
discrete storms could form as early as late this afternoon. With
CAPE >1000 J/kg in the hail growth zone, hail is a reasonable
expectation for storms that are able to develop in the late
afternoon hours. LCLs are anticipated to sit roughly around 1500ft,
and 19Z mesoanalysis suggests the presence of 100-150 m2/s2 0-1km
SRH east of I-35 with >150 m2/s2 0-3km SRH surrounding the US-36
corridor in Missouri. The tornado threat is expected to be largely
confined to the late afternoon/early evening with any supercellular
structures that are able to develop. As the northern boundary sags
south later in the evening, rapid upscale growth is anticipated,
after which point the primary threat would become damaging winds and
excessive rainfall, but a tornado cannot be entirely ruled out due
to potential boundary interactions and cell mergers. With several
models suggesting PWATs > 1.8", confidence in heavy rainfall between
the US-36 corridor and the Missouri-Iowa border is high, leading to
WPC upgrading to a slight risk of excessive rainfall through 12Z
tomorrow.

Storms are expected to retreat northward with the synoptic boundary
after midnight, though the southward portion of a QLCS coming out of
western Kansas and Nebraska could lead to brief periods of rain and
thunder in our far northern Missouri counties through sunrise.
Southerly flow will prevail on Sunday, allowing for another day of
temperatures in the mid/upper 80s. Breezy conditions will also be
widespread with sustained winds up to 15-20 MPH and gusts up to 35-
40 MPH. Much of the area is outlooked in a marginal risk for strong
to severe storms tomorrow evening, though assessment of forecast
soundings suggests the cap will be rather difficult to overcome.
Upper-level support also looks considerably better further north and
west of the CWA. Some broad and weak QG frontogenic forcing
overnight could produce or sustain some elevated showers and storms
from other portions of the Plains, but CAMs don`t seem particularly
eager on anything severe tomorrow night.

Looking ahead to Monday, an upper/mid-level trough axis is progged
to sit overhead of the Four Corners region. Throughout the course of
the day, a mid-level jet is expected to intensify, primarily into
Kansas, Nebraska, and Iowa where southwesterly flow around 80 knots
is predicted to be present. Closer to home, only about half the
magnitude of the mid-level jet is realized. A surface low pressure
center near the IA/NE/MN border with an attendant cold front will
continue to move eastward, with the cold front pushing into Kansas
and Missouri sometime Monday evening. Guidance suggests that a high
to extremely unstable airmass will spread across much of the Central
Plains. Deep layer shear is anticipated to strengthen to 40-45 kts
ahead of the cold front. High CAPE in the HGZ, DCAPE, SRH, PWATs and
low LCLs are all indicative of a robust convective environment.
Questions remain regarding the timing of the front and whether we
will see discrete convection initiate in the open warm sector.
However, confidence is high in a line of thunderstorms along the
front sometime Monday evening and/or overnight into early Tuesday
morning.

&&


.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 623 PM CDT Sat May 16 2026

Cold front will move through the area this evening, bringing
wide spread rain showers and strong thunderstorms in northern
Missouri. Heavy rainfall in northern Missouri will result in
brief IFR conditions. Most cloud bases will be VFR. Expect most
of the KC metro terminals to miss out on the heavier
shower/storm activity. Winds will remain gusty through Sunday.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...None.
KS...None.

&&

$$

DISCUSSION...Macko
AVIATION...Krull