Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

395
FXUS63 KLSX 221952
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
252 PM CDT Fri May 22 2026

.KEY MESSAGES...

- Near normal daytime temperatures are favored for the Memorial
  Day holiday weekend.

- Additional chances of showers and a few thunderstorms exist
  each day through much of next week, but there remains no signal
  for any significant widespread rainfall or stronger
  thunderstorms.


&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 248 PM CDT Fri May 22 2026

GOES-19 water vapor imagery shows a compact midlevel impulse
entering southeast Missouri, with widespread rain downstream. This
rain will continue across portions of southeast Missouri and
southwest Illinois this afternoon and move north/northeast with
time. This rain should exit from west/southwest to east/northeast
this evening, with mostly dry weather then forecast overnight
tonight through Saturday morning. By late Saturday afternoon,
scattered showers and a few thunderstorms are expected ahead of
another approaching midlevel impulse. This activity should tend to
focus along a weak surface front/trough axis that will move from
west to east through the early overnight hours Saturday night.
There should be a diurnal component to this activity as well, with
maximum coverage near the aforementioned boundary in the late
afternoon/early evening hours. As instability wanes nocturnally,
look for thunder chances to diminish and shower activity to become
more scattered.

Another mild night is expected tonight due to plenty of cloud cover.
Expect lows in the upper 50s to low 60s, or near to slightly above
normal for the date. Saturday`s highs are expected to be much warmer
than today, with low clouds in the morning forecast to lift and
scatter out. The air mass itself is also forecast to moderate as 850-
hPa temperatures climb to near +14C (right near normal). The
combination of at least some sunshine and deeper mixing should allow
for high temperatures to climb back into the upper 70s to low 80s.


Gosselin

&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 248 PM CDT Fri May 22 2026

(Sunday - Memorial Day)

Mostly dry weather is forecast Sunday through the Memorial Day
holiday. There are some low chances (20-40%) each day across
southeast Missouri and southwest Illinois. This is where a midlevel
shear axis will exist during this time period. This shear axis along
with some weak diurnal instability each day may yield some scattered
shower/weak thunderstorm activity. There is not expected to be much
change in temperatures, with slightly above normal lows each night
(upper 50s to low 60s) and highs mostly near normal (upper 70s to
low 80s).


(Tuesday - Next Friday)

The midlevel shear axis is expected to form into a closed low, which
is then forecast to migrate northward on Tuesday. There is pretty
good broad agreement in this scenario, which should portend to a
slightly cooler day on Tuesday along with increased chances of
showers and thunderstorms. The overall pattern does not change too
much through the end of next week, with another midlevel
impulse/closed low potentially moving toward the mid-Mississippi
Valley later in the week. Mild nights with near to slightly above
normal highs are expected along with daily chances of showers and
(likely weak) thunderstorms. There should tend to be at least some
diurnal component, with chances a bit higher in the afternoons/early
evenings when instability is maximized. Cluster of the 500-hPa
height pattern do show signs of a developing omega block toward the
end of next week. If this indeed happens, a drier and cooler pattern
may commence as backdoor fronts move southwest out of the Great
Lakes through at least portions of the mid-Mississippi Valley.


Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1212 PM CDT Fri May 22 2026

Low MVFR ceilings are expected to continue through tonight before
lifting and scattering Saturday morning. Model guidance also
suggests some fog, but unsure how widespread fog will or will not
be. For now, kept fog mostly confined to favored locations
(KSUS/KJEF/KCPS) but the visibility forecast is highly uncertain.
Widespread rain is expected today, though mainly in southeast
Missouri and south-central Illinois. A few light rain showers may
occur in the metro, but visibilities should stay VFR so kept them
dry.

Gosselin

&&

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

$$

WFO LSX