225 
FXUS63 KLSX 051144
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
544 AM CST Thu Nov 5 2026

.KEY MESSAGES...

- A light freeze is possible this weekend across most rural
  areas with the best chance (>80%) for sheltered river valley
  locations.

- A gradual warming trend is expected through the first half of
  next week along with dry conditions.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 147 AM CST Thu Nov 5 2026

A broad field of low-level stratus continues to spin cyclonically in 
association with a slow moving vertically stacked system across the 
Upper Midwest. The southern edge of this cloud deck is now situated 
across far northern portions of MO and the northern half of IL, 
meaning locations south of this line are mostly clear. Where it is 
clear, surface winds are lighter, which has allowed temperatures to 
lower into the mid/upper 40s compared to the lower 50s where low-
clouds are lingering. The formation of patchy fog is favored for 
locations that cleared around or shortly after sunset, which is 
generally along and south of I-70, and where the wind will be light 
enough. Therefore, the ingredients for fog are best across southern 
MO/IL and gradually get less favorable the further north, mostly due 
to more wind at the surface. River valleys across this area may 
experience more widespread, somewhat dense fog until it lifts a few 
hours after sunrise this morning.

Cyclonic mid-level flow continues to pivot southeastward across the 
Upper Midwest today, merging with a shortwave traversing into the 
Great Plains. As these features aloft move through, another cold 
front is forecast to slide north to south across the region by 
tonight. As a result, there will be a 10-15 degree gradient in high 
temperatures across the area from NW (lower 50s) to SE (upper 60s) 
by this afternoon. More low-level cloud cover, along with a low 
(20%) chance for scattered light showers, will accompany the post-
frontal airmass from later this evening into tonight. Widespread 
cloud cover tonight will lead to most locations staying in the 40s. 
If there are any breaks in cloud cover, that would allow for some 
localized upper 30s in the cooler low-lying locations.

By Friday, continued low-level CAA and lingering clouds during most 
of the day will lead to a rather small diurnal curve. Just how muted 
the diurnal heating is will greatly depend on how widespread cloud 
cover is and how quickly it clears from north to south, all of which 
are uncertain at this time. However, some high resolution guidance 
shows a much cooler scenario than the NBM, with most locations 
topping out in the 40s on Friday. Those solutions represent a 
cloudier scenario and might be too cool, but it is a signal that the 
current forecast of upper 40s to upper 50s from NW to SE by Friday 
afternoon may be too warm. Regardless, nearly the entire range of 
forecast highs in the model suite would result in Friday being the 
coolest day for the area so far this Fall season.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 147 AM CST Thu Nov 5 2026

As the mid-level trough across the Upper Midwest slides eastward, 
ridging filters into the area along with a surface high moving south 
out of the Upper Midwest on Friday. The surface high is set to 
arrive by Friday night, working to reinforce calm winds, drier low-
level air, and a mostly clear sky across the area this weekend. This 
will set the stage for efficient radiational cooling, allowing 
temperatures to reach the 30s areawide both Friday and Saturday
nights. The only exception being the St. Louis metro area that 
may struggle to cool into the 30s thanks to the urban heat 
island effect. Nearly all rural areas will at least approach the
freezing mark this weekend with many locations having a good 
chance (>50%) to fall below freezing either night. Confidence is
high that river valleys and low-lying areas across the region, 
where cold air drainage is greatest, will see the first freeze 
of the season. With 850mb temps near 5C this weekend, highs are 
forecast to be in the 50s to low 60s each afternoon.

By next week, mid-level ridging should remain in place keeping the 
area dry through at least the first half of the week. In fact, 
guidance is in good agreement with less than a 10% chance for any 
rain until next Thursday. A gradual warming trend is expected and 
revealed by LREF IQRs that become centered on values that slightly 
above seasonal normals.

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 524 AM CST Thu Nov 5 2026

MVFR to IFR CIGs are just upstream across Iowa amidst strong
cyclonic flow aloft and a reinforcing cold front entering
northern Missouri. With these features, expect ceilings to drop
to at least MVFR area wide slowly through the day. We may also
see a few sprinkles or some drizzle from the low clouds, but
these will likely be transient and brief, causing little 
impact.

Winds turn gusty out of the northwest this afternoon and
evening, weakening overnight. Low stratus lingers through the
morning tomorrow, when conditions should begin to improve with
dry air advecting into the region.

&&

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

&&

$$

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