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FXUS63 KLSX 021106
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
506 AM CST Sun Nov 2 2025

.KEY MESSAGES...

- A Dense Fog Advisory is in effect for portions of the area until 9am.
  Visibilities as low as 1/4 mile are possible within the
  Advisory.

- Dry and warm conditions are expected through most of this week.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 309 AM CST Sun Nov 2 2025

After a foggy morning, an uneventful start to the week is in store
for our slice of the Heartland. The cold airmass that followed this
weekend`s system will still be in place today, leaving insolation as
the only driving force for warming. With the cold start to the
morning, sunshine is only expected to warm the region into the 50s
this afternoon. Low-level southwesterly-westerly flow will introduce
warm air advection back to the Mid-Mississippi Valley overnight and
into the day Monday. Lows Monday morning, in turn, will be a few
degrees warmer than this morning for most, with widespread 30s
forecast. We`ll really feel the impact of the warm air advection on
Monday afternoon as 850 mb temperatures climb to 8 - 10C from
yesterday`s 0 - 2C. This translates to widespread highs in the 60s
with shallow mixing at play.

Jaja

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 309 AM CST Sun Nov 2 2025

A weak, dry cold front will pass through about half of the area on
Monday, but will have little to no impact on our sensible weather
until Monday night/Tuesday. This cold front will usher in another
bout of warm air advection as it buckles back north during the
aforementioned time period. As a result, there is decently high
confidence (50 - 80% NBM probabilities) that most of eastern
Missouri sees high temperatures reaching 70 degrees Tuesday
afternoon. Much of the same is in store for Wednesday, though
another dry cold front will bring cooler air into portions of the
region. The timing of the front and the strength of post-frontal
cool air will dictate the highs on Wednesday, but confidence is very
high (80 - 100%) that we reach the 60s again areawide with portions
of northeast Missouri and west-central Illinois a few degrees cooler
than everywhere else.

Guidance begins to diverge on Thursday due in part to the
aforementioned uncertain characteristics of the Wednesday cold
front. The NBM 25th/75th high temperature spread on Thursday ranges
from 10 - 15 degrees across the area reflecting these uncertainties.
What is certain is passage of another cold front Thursday night into
Friday. This system is shown among deterministic guidance to have
more moisture associated with it than the other two we`ll see this
week. LREF probabilities of >= 0.01" of rain on Friday range from
50 - 70% areawide, but this is very likely washed out due to
model differences and smoothing. In reality, these probabilities
will likely shrink for some and grow for others as details become
clearer over time.

Jaja

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 453 AM CST Sun Nov 2 2025

A Dense Fog Advisory is in effect until 9am. Until then LIFR to
VLIFR conditions will prevail. After that, dry and VFR conditions
will last through the end of the period.

Jaja

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Freeze Warning until 8 AM CST this morning for Audrain MO-Boone
     MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
     Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO-
     Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike
     MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Francois MO-
     Sainte Genevieve MO-Shelby MO-Warren MO-Washington MO.

     Dense Fog Advisory until 9 AM CST this morning for Audrain MO-
     Boone MO-Callaway MO-Cole MO-Knox MO-Lewis MO-Lincoln MO-
     Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Pike MO-Ralls
     MO-Saint Charles MO-Shelby MO-Warren MO.

     Frost Advisory until 7 AM CST this morning for Saint Louis City
     MO-Saint Louis MO.

IL...Freeze Warning until 8 AM CST this morning for Adams IL-Bond IL-
     Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey
     IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
     Pike IL-Randolph IL-Saint Clair IL-Washington IL.

     Dense Fog Advisory until 9 AM CST this morning for Adams IL-
     Brown IL-Calhoun IL-Pike IL.

&&

$$

WFO LSX