Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

433
FXUS63 KLSX 160907
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
307 AM CST Mon Feb 16 2026

.KEY MESSAGES...

- A warmup beings today, peaking near daily records on Wednesday and
  Thursday.

- The best chances (30-50%) of rain this work week comes in the
  form of showers and a few thunderstorms Thursday
  afternoon/evening, mainly along/east of the Mississippi River.


&&

.SHORT TERM...  (Through Late Tonight)
Issued at 259 AM CST Mon Feb 16 2026

Fog is the main concern through this morning. The latest GOES-19
nighttime microphysics RGB shows the more widespread dense fog
from western Ohio west/southwest into western Kentucky and
northwest Tennessee. This is where yesterday`s stratus departed
closer to dark. Further northwest across our area, the fog has
been mainly confined to river valleys. More specifically, portions
of the Mississippi/Missouri/Black/St. Francis Rivers are
highlighted in fog by the aforementioned nighttime microphysics
RGB. Additional river valleys are likely to see the fog too across
central/east central/southeast Missouri over the next few hours
as additional radiational cooling occurs due to light/variable
winds and a clear sky. Visibilities should improve after sunrise,
with complete dissipation of fog expected by 1400-1500 UTC.

Rapid warming will take place after the fog dissipates as
southwesterly return flow increases and 850-hPa temperatures warm
closer to +10C. Highs in the low to mid 60s are forecast, or about
15-20 degrees above normal for the date.

Milder conditions are on tap for tonight due to an increase in
mid/high level cloudiness and persistent southerly surface flow.
Lows are only expected to drop back into the low to mid 40s across
the bi-state area.


Gosselin

&&

.LONG TERM...  (Tuesday through Sunday)
Issued at 259 AM CST Mon Feb 16 2026

(Tuesday - Thursday Night)

The anomalous warmth will continue on Tuesday due to the warm start
to the day and continued low-level warm air advection. Temperatures
at 850-hPa climb above +15C (>99th percentile of climatology) on
Tuesday. However, model RH plots suggest thick mid/upper level cloud
cover and more limited mixing (only to near 950 hPa). In other
words, we will not nearly realize those anomalously warm
temperatures aloft at 850 hPa. Highs Tuesday afternoon should be
close to what was observed this afternoon for most locations.

A Pacific "cool" front is forecast to move through the area Tuesday
night, though this will effectively function more like a dry line. A
stray elevated shower or even a rumble of thunder are possible,
though the expectation is for this boundary to pass through the area
dry or mostly dry. Surface winds veer to the southwest and dewpoints
drop through the 40s into the upper 20s to mid 30s. Deeper mixing
and plentiful sunshine are also expected, which portends to an
unseasonably warm day. High temperatures are forecast to reach into
the upper 60s to mid 70s, with the warmest readings in parts of
central/east central/southeast Missouri where flow downslopes off of
the Ozark Plateau. Daily record highs at St. Louis and Columbia in
particular may be threatened. A forecast wind direction of 250/260
degrees historically has been associated with record-breaking
temperatures in St. Louis.

Forecast uncertainty increases heading into Thursday. More
specifically, with the evolution of a midlevel trough moving out of
the Rockies into the central Plains. The ECMWF and many EPS members
are stronger with this feature than the GFS/GEFS. This translates to
a slightly further northwest track of a deeper surface low in the
ECMWF/EPS compared to the GFS/GEFS. The deeper, further northwest
track of the surface low helps advect in slightly deeper moisture
into the mid-Mississippi Valley ahead of another Pacific "cool"
front/pseudo-dryline. We will have to keep an eye on this period of
time as low-topped convection/mini supercells could develop along
this boundary if there is enough instability. The GEFS/GEPS
probabilities for SBCAPE of 250+ J/kg are still low, only 20-50%
across the Mississippi River into Illinois. Those probabilities are
up however compared to yesterday. Meanwhile, the EPS, which only
has MUCAPE, does have chances of at least 500 J/kg of 50-70%
along/south of I-44 in Missouri and I-70 in Illinois.

Thursday afternoon will be another warm day, as the true trailing
cold front doesn`t look to move through the area until Thursday
night. Highs may be as warm (or even a bit warmer) than Wednesday,
particularly in southeast Missouri. Record highs though at our
climate sites are more unlikely due to the fact that daily records
on Thursday area a few degrees on average warmer compared to
Wednesday. Please see the CLIMATE section below for more details on
record high temperatures this week.


(Friday - Sunday)

Spread in ensemble guidance continues to increase to end the work
week through next weekend. Yet another midlevel shortwave trough is
likely to to move out of the Rockies across the Mississippi Valley,
but the track/strength of this feature varies considerably. If this
feature is strong enough and far enough north, it could bring some
widespread light precipitation to the region. Thermal profiles would
favor a cold rain, but couldn`t rule out some wet snow potentially.
Only one of the four clusters of the 500-hPa height pattern from the
LREF show this scenario though (~28% of total membership), so while
this is a plurality of members it certainly is not have a
majority. The three other clusters show anything from zonal flow
(26%) to midlevel ridging (24%) to broad troughing (22%). Needless
to say, uncertainty is high not only with respect to
precipitation chances during this period of time, but also
temperatures. While much cooler temperatures are all but a
certainty after the anomalous warmth through Thursday of this
week, exactly how much cooler is the question mark. The spread
between the 25th/75th percentiles of the NBM is moderately high
for highs and lows, generally around 10 degrees. That is the
difference roughly between near normal temperatures to readings
staying closer to 10 degrees above normal for late February.


Gosselin

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1020 PM CST Sun Feb 15 2026

Fog is developing in the CWA with lowest visibilities observed in
river valleys and in southeast and south-central IL. Dense fog is
expected in these portions of IL as well as southeast MO tonight,
with an Advisory lasting until 10am. Fog will dissipate by mid-
morning, and VFR conditions with southerly winds will prevail
through the end of the TAF period.

Jaja

&&

.CLIMATE...
Issued at 232 AM CST Sat Feb 14 2026

Daily record high temperatures may be threatened early/mid next
week. Here are records between Tuesday 2/17 and Thursday 2/19 at our
three official climate stations:

        Tuesday 2/17        Wednesday 2/18      Thursday 2/19
KSTL    77/1911             74/1971             77/2016
KCOU    74/2011             71/2017             77/2017
KUIN    72/2017             68/2017             72/2017


&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Dense Fog Advisory until 9 AM CST this morning for Crawford MO-
     Iron MO-Jefferson MO-Madison MO-Reynolds MO-Saint Francois
     MO-Sainte Genevieve MO-Washington MO.

IL...Dense Fog Advisory until 9 AM CST this morning for Clinton IL-
     Marion IL-Monroe IL-Randolph IL-Saint Clair IL-Washington
     IL.

&&

$$

WFO LSX