151
FXUS63 KLSX 062341
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
541 PM CST Thu Nov 6 2025

.KEY MESSAGES...

- Mild weather continues through at least Friday, but a strong
  cold front late Saturday brings a dramatic temperature plunge
  headed into the new week.


&&

.SHORT TERM... (Through Saturday) Issued at 140 PM CST Thu Nov 6
2025

Zonal flow aloft and a relatively dry airmass has kept weather
across the area quiet today. A modest surface pressure gradient
has resulted in breezy southeast winds occasionally gusting up to
20 to 25 mph, and these winds combined with relative humidities in
the 30-35% range may result in locally elevated fire weather
danger this afternoon. However, increasing moisture advection
ahead of a weak shortwave and attendant cold front may allow for
a few light showers overnight, mainly across western Illinois
where lift will be better.

For Saturday, global models continue to show a more compact
shortwave impulse diving southeast through the northern Plains.
While strong jet dynamics will promote lift, PWATs near 0.70"
suggest moisture will not be particularly bountiful. Rain chances
increase in the afternoon and wind down throughout the evening.
Indeed, model QPF remains light, and NBM probabilities of rainfall
totals greater than 0.10 inches are generally in the 30-60% range
across western Illinois and extreme eastern Missouri.

WFO SGF

&&

.LONG TERM... (Sunday through Next Thursday) Issued at 140 PM CST
Thu Nov 6 2025

Much colder Sunday and Monday:
Of greater note will be the gelid Arctic airmass that plunges into
the area behind Saturday`s cold front. NBM interquartile ranges of
high temperatures across the CWA remain fairly small (3-4
degrees), suggesting increased forecast confidence of high
temperatures only reaching the upper 30s and lower 40s on Sunday
and Monday. Probabilities of overnight low temperatures of 28 deg
C or less are quite high (70-100%), so a widespread hard freeze
appears likely. Furthermore, winds of 10-20 mph may support wind
chills dropping into upper 20 to the teens both nights.

However, ensemble guidance suggests this cold snap will be short-
lived as clusters depict rough agreement in shifting the
aforementioned trough axis into the eastern CONUS by Tuesday, and
warm air advection begins to push temperatures upward. The primary
differences between the ensemble clusters relate to the ridge
magnitude and positioning over the western and central CONUS.
More practically, these details will affect the magnitude of
warming we experience next week.

Monitoring elevated fire danger on Tuesday:
With warm air advection from breezy southwesterly winds and a dry
airmass over the region, Tuesday could feature an elevated fire
weather risk. Additionally, dead vegetation from the early week
freeze could provide dry fuels for fire starts and spread. The
latest NBM probabilities of sustained winds greater than 15 mph
are currently in the 25-60% range across eastern Missouri and
western Illinois, but model trends will have to be monitored in
the coming days for increasing forecast confidence in the details.

WFO SGF

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 540 PM CST Thu Nov 6 2025

South and southeast winds precede a cold front that will push
through the region from the northwest tonight. The front will
result in mid-level, VFR clouds and a few showers, mainly near
KUIN. A quick, high-end MVFR vsby restriction is possible, but I
would expect this to be more rare than common.

The cold front will cause winds to back out of the west late
tonight, then northwest Thursday. VFR persists.

Maples

&&

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

$$

WFO LSX