Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

384
FXUS63 KLSX 082334
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
634 PM CDT Wed Apr 8 2026

.KEY MESSAGES...

- Above average temperatures continue for most of the area into
  early next week.

- An active pattern is forecast with multiple chances for showers
  and thunderstorms Thursday night into Friday night (60-80%) and
  again Sunday night into early next week (40-60%).


&&

.SHORT TERM... (Through Late Friday Night)
Issued at 238 PM CDT Wed Apr 8 2026

Strong southerly flow out ahead of an approaching weak cold front
has aided in a quick warmup today with areawide temperatures sitting
in the low/mid 70s this afternoon. Abundant solar insolation has
helped to mix in drier air, which has slightly counteracted the
moist advection. This has resulted in scattered relative humidity
values in the upper 20s for locations across the Ozarks and east-
central MO which has led a few areas within the locations mentioned
to reach Elevated Fire Danger criteria this afternoon.

A mid-level trough is traversing west-east today into Thursday
across the US-Canadian border with its surface reflection following
suite. The system`s weak low-level cold front has been slowly moving
southward today and is now positioned near northwest Missouri
northeastward into southern Wisconsin and is expected to stall near
northern MO until Friday. Rain chances are best along/north of this
front, collocated with the strongest low/mid-level frontogenesis and
greatest moisture convergence. High-res guidance resolves scattered
showers nudging into northeastern MO overnight as the weak cold
front settles nearby, with the REFS indicating only a 10-20% chance
for 6hr QPF >0.01", reinforcing the idea that most locations across
northern MO should remain dry overnight. With the quasi-stationary
front forecasted to be slightly north of our area on Thursday,
placing the area in continued southerly flow, another warm day is on
tap with highs in the 70s across northern MO/west-central IL and
widespread 80s elsewhere. Winds will be slightly more southwesterly,
potentially leading to lee downsloping off the Ozarks that would
boost temperatures and lower relative humidity values lower than
what guidance resolves. As a result, there is a low chance (20-40%)
of Elevated Fire Danger for similar locations again tomorrow, with
wind being the greater limiting factor since they will be calmer,
generally in the 5-15mph range.

A secondary, more transient and less amplified shortwave within the
northern stream swings southeastward into the Northern Plains late
on Thursday with nebulous areas of mid-level energy advancing nearby
into Friday. The progression of these mid-level features work to
slowly shunt the weak quasi-stationary cold front southward on
Friday, bringing slightly cooler air (60s) and increased rain
chances to the area. As the front slowly moves equatorward on
Friday, low/mid-level moisture convergence increases along and ahead
with the REFS unveiling 1-1.2" PWATs (90th percentile). As the front
pushes southward through the region, nebulous areas of mid-level
energy and a band of low-level frontogenesis accompanying the front
should provide enough forcing for showers along with an isolated
weak thunderstorm on Friday. Most of deterministic guidance settles
the slow moving cold front near southern MO Friday night with rain
chances accompanying it. With the front dropping south across the
area on Friday, a slightly larger range in high temperatures will be
realized with low 60s across northern MO/west-central IL and upper
70s/low 80s across southern MO/IL where southerly winds will remain
in place as peak heating occurs.

Peine/Elmore

&&

.LONG TERM... (Saturday through Next Wednesday)
Issued at 238 PM CDT Wed Apr 8 2026

At the start of the extended, a longwave trough will be positioned
across the western CONUS while a weak mid-level ridge will be out
ahead of it pushing eastward into our area Friday night. Mid-level
height rises persist into Saturday night, which boosts confidence in
an areawide break from any rain chances with the window for dry time
centered on Saturday afternoon into Sunday morning. A shortwave
within the western longwave trough ejects into the Plains Saturday
night, which will lift the same quasi-stationary front, that will be
positioned across southern MO, poleward as a warm front on Saturday.
With warm air advection working its way northward across the area, a
moderate range in high temperatures is expected with upper 60s
across northern MO/west-central IL while central/east-
central/southern MO and southern IL should reach the 70s/80s by
Saturday afternoon.

An active stretch of weather is on tap from Sunday night into mid-
week due to several pieces of shortwave energy that eject into the
Plains out ahead of a slow propagating longwave trough out west.
This large-scale setup places our region in deep southerly flow that
will result in abundant warm/moist advection Sunday into Tuesday,
with LREF PWATs maxing out around 1.2-1.4" (95th-99th percentile) on
Monday with 90th-95th percentile PWATs (1.2-1.3") lingering until a
strong cold front pushes through sometime Tuesday night into
Wednesday. For our area, this setup means that we will be stuck in
deep southerly flow, leading to above average temperatures
(widespread 70s/80s). Along with multiple chances for showers and
thunderstorms, some of which may be severe, particularly on Monday
and Tuesday. Analyzing the LREF joint probabilities for SBCAPE
>500J/kg and 0-500mb Bulk Shear >30kts, chances are highest on
Monday and Tuesday when probabilities reach over 50% for a good
portion of our area. The key take away here is that given the time
range (5+ days), many uncertainties remain with respect to severe
weather potential, but it is important to note that the signal is
there for severe weather at the start of next week. Heavy rain also
becomes an item of concern with a large-scale pattern like this with
the LREF mean accumulated precipitation through next Wednesday
highlighting a broad swath of 1-2" across the area with the higher
totals over western MO. Given the convective nature from which a lot
of the rain early next week should occur with, the potential higher
end totals have been washed out in the mean LREF and won`t be
realized until high-res guidance is within range. Most noteworthy is
that the potential is there for heavy rain with this upcoming
pattern and is something to monitor with future forecasts.

Peine/Elmore

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 628 PM CDT Wed Apr 8 2026

VFR conditions are expected for a majority of the TAF period, with
a few weather items to note. First, gusty south winds will weaken
after sunset, and a few weakening showers may approach UIN
overnight. However, precipitation probabilities are too low (below
20%) to include in the TAF, and more likely the terminal will see
only increasing mid level clouds.

Modest southwesterly winds will resume tomorrow but will be weaker
overall than today. A scattered to broken cumulus deck is also
likely to develop by early/mid afternoon, but flight categories
are not likely to be reduced. Chances for showers and
thunderstorms increase at UIN near the end of the period, but this
activity should remain north of all other terminals until after
06Z Friday.

BRC

&&

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

$$

WFO LSX