667 
FXUS63 KLSX 090348
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
948 PM CST Sun Nov 8 2026

.KEY MESSAGES...

- The next chance (30-40%) for light rain on comes on Wednesday. 

- Temperatures will start the week above normal (highs in the
  60s- 70s) and end the week below normal (highs in the
  40s-50s).

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 217 PM CST Sun Nov 8 2026

Upper-level ridging can be seen in water vapor imagery building 
eastward into the Middle Mississippi Valley as the trough from late 
last week continues to move through the Northeast. The building 
ridge is pushing the surface high responsible for our recent weather 
gradually eastward. With this, low-level ridging is building into 
the region, with increasingly southwesterly flow weakly advecting 
warmer air over the CWA. As a result, temperatures this afternoon 
are trending about 10 degrees warmer than at this point yesterday. 
This general pattern holds through Tuesday, with daily temperatures 
running about 10 degrees above normal through this stretch. 

Overnight lows tonight will still be cool enough to lead to a threat 
of valley fog mainly over the Ozarks. The surface high's gradual 
shift eastward is expected to mostly mitigate fog development 
Monday and Tuesday nights.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 217 PM CST Sun Nov 8 2026

A strong upper-level trough will impact our local weather through 
the duration of the extended forecast period. Guidance consensus is 
that this trough will begin rapidly digging into the eastern half of 
the country on Wednesday, with an initial shortwave passing through 
the Middle Mississippi Valley then. Over the last 24-36 hours, a 
majority of guidance has this wave inducing cyclogenesis somewhere 
over the Central or Southern Plains and tracking the low 
northeastward through the Midwest. While there is much spread in the 
track of this low among guidance, confidence is increasing that it 
or at the very least its cold front will directly impact the CWA. 
This has led to increasing chances (currently 30-40%) for rainfall 
across portions of the CWA, with these chances expected to increase 
as guidance spread decreases in the coming days. Both 
instability and QPF are meager with this system, so severe 
weather and heavy rainfall are not expected. While the forecast 
beyond Wednesday is dry, additional rounds of light rainfall 
cannot be ruled out through Friday-Saturday as additional 
shortwaves rotate through the trough. At this lead time, 
guidance does a notoriously poor job at accurately resolving 
these subtle features, hence the dry forecast.

Possibly the bigger story with this trough is a blast of late fall 
air that will move into the region to end the week. With guidance 
consensus showing an increasingly potent trough, temperatures among 
ensembles and deterministic guidance continue to cool. In the wake 
of Wednesday's surface system, below normal temperatures are 
expected at least Thursday and Friday, with Friday being the 
cooler of the two days. Then, nearly all guidance has a majority
of the CWA seeing highs in the 40s. Confidence in temperatures 
as we head into the weekend decreases significantly as guidance 
diverges on the phasing of the trough and how quickly it departs
the area. Temperatures will moderate; though how quickly is 
uncertain at this lead time.

&&

.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/... 
Issued at 945 PM CST Sun Nov 8 2026

Latest guidance isn't as bullish on fog tonight. While there may
be less widespread 2-5 mile fog overall, still think IFR steam 
fog with visibilities at or below 1SM is likely near bodies of 
water before sunrise on Monday. Any fog that develops should
dissipate by 14-15Z. Elsewhere and otherwise, VFR flight
conditions and light winds are expected outside of the fog
tonight. There may be fog again on Monday night, and will
continue to evaluate that possibility in subsequent forecasts.

&&

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

&&

$$

SHORT TERM...Elmore
LONG TERM...Elmore
AVIATION...Carney