Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

039
FXUS63 KLSX 100403
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1103 PM CDT Thu Apr 9 2026

.KEY MESSAGES...

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

- Showers are likely (50-90%) with a low chance (20-30%) for an
  isolated thunderstorm tonight into Friday night.

- Several chances for showers and thunderstorms will impact the
  region Sunday into Wednesday, with potential for severe
  thunderstorms early next week.


&&

.SHORT TERM... (Through Late Saturday Night)
Issued at 146 PM CDT Thu Apr 9 2026

Southwesterly surface winds favoring downsloping off the Ozarks
along with a mostly sunny sky today have boosted temperatures into
the low 80s for much of central/east-central/southern MO. Relative
humidity values have reached the low 30s with scattered readings in
the upper 20s across the region mentioned above. This coupled with
10-15mph sustained winds has led to Elevated Fire Danger and the
potential for erratic fire behavior, which is why burning is
strongly discouraged this afternoon and evening.

A weak cold front is stretched from northern KS northeastward into
southern IA/northern MO with showers and scattered thunderstorms
pushing eastward along the front. A mid-level shortwave swings
southeastward out of Canada into the Upper Midwest tonight which
nudges the stalled frontal boundary south. High-res guidance
resolves increasing coverage of showers and thunderstorms across
northeastern KS/northwestern MO later this evening as the
nocturnally driven low-level jet ramps up. 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). Showers (60-90%) along with scattered thunderstorm
chances (20-30%) increase late this evening across northern and
central MO/west-central IL with shower chances (50-80%) slowly
moving southward with the cold front, reaching the I-70 corridor
around mid-late morning on Friday. However, coverage of
showers/isolated thunderstorms along the front is expected to be
lower into the day on Friday as the low-level jet weakens quickly.

The cold front is forecast to settle across southern MO by Friday
evening before lifting poleward as a warm front on Saturday in
response to surface cyclogenesis across the High Plains. As the
front lifts northwards, chances (20-60%) for scattered showers or an
isolated thunderstorm accompany it, with the best chances for
precipitation across central MO Friday night into Saturday morning.
A weak mid-level ridge will be moving into the region, leading to
height rises aloft that should limit overall precipitation coverage
and thunderstorm potential on Saturday, with potential for most of
the area to remain dry after Saturday morning. With the frontal
boundary well north and west of the area by Saturday afternoon,
southerly flow returns opening the door for abundant warm/moist
advection into the region. With the mid-level ridge traversing the
area Saturday into Sunday, a period of dry conditions is likely (80-
90%) Saturday evening with NBM probabilities for QPF >0.01" lowering
to less than 10% for the area. Also, with most of the area back in
the warm sector for the day on Saturday, afternoon highs are
expected to be warm.

Peine/BSH

&&

.LONG TERM... (Sunday through Next Thursday)
Issued at 146 PM CDT Thu Apr 9 2026

On Sunday, there will be an amplified longwave trough across the
West Coast with weak downstream ridging pushing east across the Ohio
River Valley. With the ridge axis advancing through the area on
Sunday, mid-level heights will begin to fall as an active
southwesterly flow regime takes hold on the region. Long-range
deterministic guidance resolves nebulous areas of energy along with
a few subtle shortwaves that propagate northeast into the Plains and
Midwest out ahead of the main longwave trough. The result for us
will be increased chances for showers and thunderstorms from Sunday
into at least midweek, when the longwave trough is progged to
finally eject across the region.

Our persistent deep southwesterly flow regime, providing efficient
warm/moist advection, will lead to a steady increase in temperatures
and instability, which will also result in increased chances for
thunderstorms, some of which may be severe. The latest model
guidance is keying in on a shortwave advancing northeastward across
the Midwest Sunday into early Monday, which is when shower and
thunderstorm chances increase to 40-70% from west to east, with the
greatest chances across Missouri. Monday may feature a brief period
of drier conditions as a muted ridge, apparent by a relative lull in
nebulous areas of mid-level energy, moves into the Central Plains
and Upper Midwest. This is shown well by the LREF probabilities for
6hr QPF >0.01" as they lower to less than 20% for the entire area.

Long-range guidance is resolving the longwave trough pushing east
and ejecting into the Plains sometime between Tuesday and Wednesday.
Conceptually, the greatest severe weather risk for our area would be
when this trough does eject, bringing more robust forcing and deep-
layer wind shear to support severe thunderstorms. It is important to
note that features like cloud cover and the timing of more robust
forcing/shear with respect to diurnal instability maximums has a
great influence on the severe weather threat that is realized. All
of this said, a lot of uncertainty remains in regards to our chances
for severe weather Tuesday into Wednesday. As a result, most of our
area is included in the SPC severe weather outlook for Monday and
Tuesday, with the entire area highlighted for severe weather
potential on Wednesday. Temperatures will remain warmer than average
as indicated by LREF IQR temperature spreads of 5 degrees centered
near 5-15 degrees above average for the entire area Sunday through
next Thursday.

Peine/BSH

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1048 PM CDT Thu Apr 9 2026

The main concerns during the 06Z TAF period continue to be the
potential for showers and a few thunderstorms from late tonight
through early tomorrow afternoon, followed by low ceilings behind
a front.

A slow-moving and broad band of showers and a few thunderstorms is
expected to move through all sites between late tonight and early
tomorrow morning. Thunderstorms are most likely initially at UIN,
followed shortly by COU/JEF. While some lightning is possible at
STL/COU/JEF during the day tomorrow, this is not likely enough to
include in the TAF. From mid morning to early afternoon, a cold
front will sink into the area, bringing a round of low ceilings,
likely to MVFR levels. Some IFR ceilings are also possible for
brief periods. Confidence is low that clouds will clear anywhere
except UIN before the end of the period.

BRC

&&

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

$$

WFO LSX