819
FXUS63 KLSX 031150
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
550 AM CST Tue Nov 3 2026

.KEY MESSAGES...

- Widespread showers and isolated thunderstorms along with
  breezy southerly winds (gusting 30-40 mph) are expected across
  the area today ahead of a cold front.

- A marginal (level 1/5) severe weather threat exists today,
  though storm development remains conditional. If severe storms
  manage to form, the main threats will be damaging wind gusts
  and a brief tornado.

- Temperatures closer to seasonable normals are forecast by the
  end of the week.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 310 AM CST Tue Nov 3 2026

Recent mid-level water vapor imagery reveals broad southerly flow
enveloping the region early this morning as a rather amplified
mid/upper-level trough axis swings into the Great Plains. The
surface reflected cyclone is across eastern KS with a swath of
ongoing showers and thunderstorms across eastern OK and KS as of 07z
this morning. As all of these features lift northeastward,
widespread showers along with isolated thunderstorms gradually make
their way through the area today. A strong surface pressure gradient
will result in peak sustained winds of 15-20mph (gusting ~35mph)
early this morning through the early afternoon timeframe. By later
this evening, winds should slightly lower to sustained values of 10-
15mph (gusts ~20-25mph). With strong (40kt) winds just above the
surface today, any showers/weak storms or breaks in cloud cover
could allow these gusts to briefly mix down resulting in isolated
non-convective wind gusts over 40mph through this afternoon.

Model guidance is in good agreement that the eastward motion of the
mid-level trough continues to slow through the day as it begins to
lift northward and phase with the northern stream. As a result,
height falls aloft will be gradual and fairly weak over the area,
leading to a scenario that does not favor the development or support
for strong to severe thunderstorms. On the other hand, wind shear
will not be in short order, with 30-40kts of 0-6km bulk shear
accompanying pockets of 200-330 m^2/s^2 of 0-1km SRH. The limiting
factor with this setup still appears to be the lack of instability,
with both the HREF/RRFS indicating SBCAPE values of only 250-350
J/kg, which is has gone up slightly over the last 24 hours.
Regardless, with the abundant shear in place, this little amount of
instability may not be enough to produce organized or sustained
updrafts as convective attempts might tend to get sheared apart.
However, low-level curvature in hodographs signals that if some
convection becomes organized/sustained for even a brief window, a
weak tornado or two is possible. Along with that, a threat for
damaging winds could accompany a few of the stronger storms given
the 40kt+ winds just above the surface. As of now, the best overlap
of sufficient shear and better instability looks to be this
afternoon across central/northeast MO, just ahead of the approaching
cold front. The favorable overlap of these two parameters should
fade with eastward extent/later in the evening, when instability
lowers even further after sunset.

The cold front extending to the SSW from the surface cyclone pushes
through the area this evening and exits tonight, veering winds from
southerly to westerly. Low-level winds behind this boundary will be
blowing nearly parallel with the thermal gradient, resulting in very
little CAA. In addition, an upstream trough currently across CA,
will quickly move eastward and slide in right behind the slowly
departing trough that is currently over the area. This leads to
continued southwesterly flow aloft through at least Thursday, which
does not support the advection of any colder air. However, even
without much low-level CAA behind tonight`s front, Wednesday will
feature highs that are about 5-10 degrees cooler than today, which
is closer to seasonable normals.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 310 AM CST Tue Nov 3 2026

Cloud cover is forecast to be slow to clear with continued cyclonic
flow aloft across the area resulting in wrap around moisture into
Wednesday night. There is some signal for clearing, from south to
north by Thursday, which may work to boost afternoon highs about 5
degrees warmer than Wednesday. That would result in highs ranging
from the low 60s to low 70s across the area by the afternoon.

By Friday, the mid-level trough that is currently across CA finally
traverses across the region, bringing an increase in cloud cover and
a 20-30% chance for more rain, along with another cold front. This
front appears to actually shift low to mid-level winds out of the
north, advecting in some cooler more seasonable air. Analysis of
LREF IQRs indicates good agreement that temperatures behind this
front would be about 10 degrees cooler. This would bring areawide
highs into the upper 50s/lower 60s, with lows in the lower 40s/upper
30s. In fact, NBM probabilities for lows <32F reach about 50% for
valley locations across the Ozarks later this weekend into next
week, indicating the potential for a first freeze may not be too far
away for some.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 550 AM CST Tue Nov 3 2026

A swath of widespread showers and isolated thunderstorms is
currently located across central/northeast MO. This activity is
lifting to the northeast with very slow movement to the east, making
for a lower confidence forecast regarding the estimated onset time
of rain for terminals across the area. Most of the showers will be
capable of prevailing MVFR visibilities with scattered heavier
showers having the potential to result in brief IFR visibilities.
Thunderstorm activity and coverage is expected to be limited with
around a 20% chance for thunderstorms to impact any given terminal
through the day. Widespread low MVFR ceilings are forecast at all
local terminals today. There is potential for a brief window of VFR
conditions later this evening, in between the exiting showers, and
another round of low MVFR ceilings that will impact the entire area
through Wednesday morning. Southerly surface winds will be strong
today (sustained 15-20mph, gusting 25-35mph) with the strongest
winds forecast to be across east-central MO and to the northeast. A
cold front moves through from west to east this evening and into
tonight with winds veering from southerly to westerly and slackening
off to around 10kts behind the front.

&&

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

&&

$$

SHORT TERM...Peine
LONG TERM...Peine
AVIATION...Peine