Area Forecast Discussion

228
FXUS63 KLSX 081706
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1106 AM CST Sun Feb 8 2026

.KEY MESSAGES...

- A warming trend begins today with Monday and Tuesday being the
  warmest days of the week.

- Chances for measurable rain Tuesday into Wednesday have
  decreased across the entire area with the best chances (20-40%)
  to the south of I-70 in both Missouri and Illinois.

&&

.SHORT TERM... (Through Late Monday Night)
Issued at 406 AM CST Sun Feb 8 2026

Southerly flow early this morning will continue to bring warm air
into the region that will limit how much further temperatures fall
for certain locations more than others. A west-east gradient in
morning lows will exist with the warmest temperatures at sunrise, in
the mid 30s, out over central Missouri due to stronger return flow.
Locations across Illinois will start off in the mid/upper 20s due to
less warm air advection and snow pack that still remains to the east
of the Mississippi River.

A clipper within the northern stream will approach the region today
from the northwest, phasing over the southern Plains with a few
small disturbances in the southern stream. The Pacific nature of this
clipper system means that moisture is limited to what the southern
stream disturbance`s transport northeastward before phasing occurs.
As a result, model guidance keeps our region dry with any chances
for rain remaining south across Arkansas. Additionally, there is
signal for a feeble surface reflection to push into the area from
the west this afternoon. Given the lack of mid/upper-level support
with this clipper system, the surface low won`t pack much of a punch
besides some higher level cloud cover today along with calm and
variable winds starting later this evening. As a result, the
forecast remains on track for a moderate warmup to commence today
with the greatest warmth expected across central Missouri where
southwesterly winds will boost afternoon highs into the low 60s.
Further to the east along the Mississippi River, afternoon
temperatures should reach the mid/upper 40s, while most locations
across Illinois will struggle to warm out of the 30s thanks to the
stubborn remaining snow pack that will inhibit warming.

As the clipper system departs on Monday, brief mid-level ridging
moves in from the west allowing heights aloft to rise. This, coupled
with increasingly strong southwesterly surface flow under a mostly
sunny sky will lead to an efficient warmup for the entire area. Once
again central Missouri and the Ozarks will be the warmest due to
warmer morning lows and stronger warm air advection than compared to
areas off to the east. Locations across Illinois will still manage
to reach the 50s despite starting the day off in the lower/mid 20s.
Lastly, most locations west of the Mississippi River will warm into
the mid 50s with mid 60s further west and maybe even some upper 60s
out across far central Missouri and the Ozarks.

Peine/Elmore

&&

.LONG TERM... (Tuesday Morning Through Next Sunday)
Issued at 406AM CST Sun Feb 8 2026

A potent mid-level shortwave trough will be traversing within the
northern stream along the US-Canadian border on Tuesday with its
surface reflection north of Wisconsin in southern Canada. The strong
surface low will send a cold front our way, potentially knocking on
our northern door by early Tuesday morning. The precise timing of
this front, which remains largely uncertain, will be crucial
regarding how warm the region gets and how far north the rain
reaches before being shunted south by the front. Over the last 24
hours, this cold front has trended faster, due in part to a few
noticeable changes. The first one being that ensemble members have
delayed the phasing of the mid-level closed low over Baja California
with the northern stream by a day or so. Secondly, the northern
stream shortwave has trended stronger, resulting in a more amplified
and southward evolving system, thus leading to a quicker propagating
cold front on Tuesday. The combination of these altered variables
will limit both the duration of warm air advection and moisture
return out ahead of the cold front and has resulted in cooler
temperatures and lower rain chances on Tuesday.

With the frontal passage ranging from as early as Tuesday morning to
as late as Tuesday afternoon, uncertainty in afternoon highs remains
large, which can be unveiled by the 15+ degree IQR spread between
the 10th and 90th percentiles on both the LREF and NBM. It is
important to note that even the 10th percentile still results in
highs about 10 degrees above normal, indicating that confidence is
high in Tuesday remaining much warmer than climatology. Areas south
of I-70, that could remain under the warm pre-frontal airmass
longer, have a 30-50% chance of reaching 60 degrees on Tuesday.
Additionally, the best chances for rain (50-70%) have now been
shoved south out of the area to the Missouri-Arkansas border. For
areas north of I-70, rain chances now appear slim to none with
latest LREF probabilities for QPF >0.01" less than 10%. In fact,
LREF probabilities for the far southern counties in our CWA have
lowered down to 20-40%. The rather large shift in model guidance
over the last 24 hours has resulted in a lower confidence forecast
with measurable rainfall looking increasingly unlikely to occur for
a majority of the area.

Our upper-level pattern is forecasted to become increasingly active
with quasi-zonal to west-northwesterly flow bringing several
shortwaves across the area Thursday into next weekend. For this
period, ensemble guidance has trended toward more influence from the
northern stream, which has resulted in slightly colder temperatures
than previously forecasted. Long range guidance is keying in on the
first shortwave approaching the area Thursday into Friday as a
clipper system, bringing a 30-40% chance for precipitation across
the region. Slightly colder air will potentially be in place for
this clipper system so all types of precipitation remain possible
but appear to be light, given the typical lack of moisture with
clippers. With the colder post-frontal airmass in place and
continued mid/upper-level northwesterly flow Wednesday into next
weekend, temperatures look to remain at or slightly above
climatological normals for mid-February. However, there is a signal
for a slow warming trend Thursday into next weekend shown by the
steady and subtle increase in LREF IQR`s for high and low
temperatures.

Peine/Elmore

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1103 AM CST Sun Feb 8 2026

Dry, VFR conditions are currently forecast through the TAF period,
though there is a signal for some fog generally along the
Mississippi River tonight in some guidance along with a weak warm
front and increase in moisture. Currently, it seems that wind may
be a touch too strong to promote fog that would degrade flight
conditions, though this trend will be monitored in future updates.
The best chance for terminal impacts is at KUIN, which does have a
line in its TAF acknowledging a slight VSBY restriction before
sunrise.

MRB

&&

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

$$

WFO LSX

NWS LSX Office Area Forecast Discussion