Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

586
FXUS63 KLSX 142337
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
637 PM CDT Tue Apr 14 2026

.KEY MESSAGES...

- A low chance (20%) exists for an isolated strong to severe
  thunderstorm this afternoon/evening. A better chance (40-60%)
  for a round of strong to severe thunderstorms exists overnight.
  Large hail and damaging winds are the primary threat.

- An additional chance for strong to severe thunderstorms exists
  Wednesday afternoon into Wednesday night. Once again, the
  primary threats are large hail and damaging winds with lower
  potential for tornadoes.


&&

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 324 PM CDT Tue Apr 14 2026

Analysis of recent GOES-East mid-level water vapor imagery reveals
longwave troughing near the Four Corners Region with ridging across
the eastern U.S., placing our area under a southwesterly regime.
Strong and persistent southerly flow, continuing to advect Gulf
moisture into the region, has helped to boost instability, with
MLCAPE values well over 2,000 J/kg (99th climatological percentile)
for much of the area. The latest ACARS soundings out of KSTL (18Z)
reveals a slightly capped environment, with MLCIN around
-20 J/kg correlated with an 800mb capping inversion. A few isolated
showers, with occasional flashes of lightning have been pushing
eastward across IL this afternoon, struggling to intensify. With the
past behavior of these showers, indication is that a weak cap is
still in place for the time being, supporting the KSTL ACARS
sounding. Some high-res guidance fires an isolated thunderstorm or
two across the area this afternoon/evening across an environment
that is favorable to support supercells, should a storm overcome the
inversion, tapping into the anomalous instability available. As a
result, confidence is low in an isolated strong to severe
thunderstorm this afternoon/evening. The best chance for this would
be the result of a subtle mid-level forcing mechanism (shortwave)
passing over and/or localized areas of surface and moisture
convergence occur. All of which even high-resolution guidance can`t
resolve with detail or accuracy, lending to the lower confidence.
Lastly, if scattered convective initiation occurs, storms that form
would have potential to become severe with large hail and damaging
winds the primary hazards.

Further upstream, across OK/KS, CAMs are keying in on convective
initiation this afternoon/evening, with eventual upscale growth
leading to a remnant convective system approaching the region later
this evening into the overnight hours. Model guidance reveals that
this convection will be initiating off a more apparent mid-level
shortwave within the southwesterly flow. With a larger scale feature
at play that models are able to resolve, confidence is high in
convective initiation across OK/KS and eventual upscale growth of
storms into our area. Atmospheric instability across our area will
steadily be decreasing with the loss of insolation, which is
indicated well by forecast model soundings. As a result, this
complex of thunderstorms is forecast to gradually weaken with
time/eastward extent. However, these storms still has good potential
to be severe across our area since HREF mean SBCAPE values are
around 1,000-1,500 J/kg when these storms are modeled to enter the
area. Any remaining severe thunderstorms would be capable of
producing large hail and damaging winds, with a lower threat for
tornadoes.

On Wednesday, model guidance reveals a few subtle shortwaves
propagating northeastward across the region on Wednesday that could
result in a messier setup with more abundant showers and convection.
Confidence is low in the potential regarding any lingering
convection or additional rounds of storms originating upstream from
OK/KS Wednesday morning and into the day. The evolution of daytime
convection across our area will have a great influence on the severe
weather threat that is realized Wednesday afternoon/evening.
Kinematically speaking, Wednesday will feature greater shear as the
mid/upper-level longwave trough out west ejects into the Plains by
Wednesday afternoon. As a result, HREF mean 0-6km Bulk Shear
steadily increases from Wednesday morning until Wednesday
night/early Thursday, when it peaks around 40-45kts as the longwave
trough advances over the area. Our greatest threat for severe
weather is still forecast to be Wednesday afternoon into Wednesday
night as a cold front moves through northwest-southeast. As of now,
the main hazards associated with this severe threat are large hail
and damaging winds with a low risk for tornadoes. A severe weather
threat may linger into early Thursday across parts of southeast
MO/southwest IL, as that is where the cold front will take the
longest to exit.

Peine

&&

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 324 PM CDT Tue Apr 14 2026

NAM/GFS are in general agreement that a shortwave trough will move
east of the area early in the day on Thursday. An attendant
surface cold front/trough will move across Missouri/Illinois with
only weak convergence along it will be enough to generate showers
and scattered thunderstorms, mainly over the southeastern half of
CWA (60-80% chance) of the CWA during the morning before shortwave
ridging begins moving in from the west. Then it looks like there
will be a period of dry weather on Thursday night as the ridge
moves across the area before southwesterly flow sets up over the
area on Friday ahead of trough that be moving across the Plains.
Chances for showers and thunderstorms will increase late in the
day Friday and especially Friday night as ascent from the trough
and forcing from the associated surface front will move into the
CWA during the night in an unstable and sheared environment. These
storms look to be the result of upscale growth from storms that
will develop in the Mid Missouri Valley on Friday afternoon and
evening. There is good agreement in the medium range models with
little spread in the LREF. This front is currently on track to
move through the area on Saturday which would bring an end to the
showers and thunderstorms from west to east. Even with this said,
if the trough/front does speed up on Friday, then there will be a
greater chance for severe weather here on Friday vs if is slows
down, there would be the possibility we could see strong/severe
thunderstorms on Saturday. By early next week, mainly dry weather
is expected as northwesterly flow sets up over the area and a
large surface high moves across the area. Very few (<10%) of the
LREF members are producing precipitation over the area early next
week.

High temperatures will be in the 70s and 80s through Friday ahead of
the front before temperatures drop to around 60 degrees on Sunday
behind the front.  There will be some rebound in highs by Monday and
Tuesday as they climb back into the 70s.

Britt

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 628 PM CDT Tue Apr 14 2026

Convective trends are the main concern tonight. There is a very
low (<20%) of storms developing through the evening, but we are
also watching an area of storms upstream in Oklahoma. These storms
may try and enter central Missouri after 0400 UTC, but they should
tend to weaken with time. Thunderstorms are also possible again on
Wednesday, with the early/mid afternoon time period being the
mostly likely time frame. Visibilities in thunderstorms may
briefly drop to IFR/MVFR due to downpours. Gusty winds may also be
a threat.

Gosselin

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX