653
FXUS63 KLSX 101705
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1105 AM CST Tue Feb 10 2026

.KEY MESSAGES...

- A cold front will press southeastward through the region today,
  creating a disparity in high temperatures (50-75 degrees) from
  north to south.

- Despite a drop in temperatures behind the cold front, it remains
  as much as 10 degrees above normal (upper 30s to mid-40s)
  leading into the upcoming weekend.

- Precipitation chances are limited until Saturday, when a system
  brings greater promise of widespread rainfall.


&&

.SHORT TERM...  (Through Late Wednesday Afternoon)
Issued at 342 AM CST Tue Feb 10 2026

A cold front extends southwest of a surface low that is passing over
the northern section of the Great Lakes early this morning. A
second, weaker surface low is positioned over northern OK, which
will track eastward along/ahead of the front through the day today.
As of 09z this morning, the front was draped from northwest IL
through northwest MO. Latest analysis and timing projections bring
the front through northern sections of the CWA early this morning
around 12z. The front then sags south toward I-70 around 17-18z and
clear most of the CWA by 21z.

The front boundary lead to a large disparity in temperatures.
Sections of northeast MO and west-central IL are capped near 50
degrees, while ahead of the front mixing deepens up to around 850MB,
where temperatures are right around 15C. Should current timing play
out, areas of southeast Missouri could reach the 70s with a few mid-
70s across Reynolds, Iron, and Madison Counties. Temperatures spreads
of up to 20 degrees  Winds increase off the deck, but aren`t too
terrible with an occasional gust near 20-25 mph, mainly over
northeast Missouri. Recent slowing of the front has created a wide
spread in potential highs south of the front (along/south of I-
44/south of I-70 in IL) this afternoon. Inclination is to continue
to lean toward the warmer temperatures over the southern CWA with
the late arrival of the boundary.

Cooler air to the northeast is pushed back to the west/southwest,
resulting in about 15C mid-level temperature drop and advancing the
0C 850MB isotherm southwestward to bisect the CWA. While cooler,
average highs range from the upper 30s to mid-40s. Even in the
cooler air, temperatures remain mild. Few areas will be closer to
normal, while much of the area is as much as 10 degrees warmer than
normal. Dry conditions continue through the end of the period.


Maples

&&

.LONG TERM...  (Wednesday Night through Monday)
Issued at 342 AM CST Tue Feb 10 2026

On Thursday, a northern stream, mid-level shortwave tracks southeast
from near the MN/IA border through northern Illinois. The wave
passes along the western side of a surface ridge with dry air. Weak
mid-level WAA extends southeast from the shortwave and just about
parallel with the Mississippi River. However, there is very little
eastward progress with the milder air. As the shortwave moves over
northern Illinois, NAM model soundings show saturation extending
between 750MB-500MB. A roughly 125MB dry layer resides below with
dewpoint depressions of up to 20-25 degrees. Additionally, the
shortwave becomes more muted with time. This, along with recent
trends, does not support widespread rainfall. LREF spreads keep QPF
around 0.10" or less with the 90th-10th percentile spread yielding
0.07-0.10" difference between the high/low amount.

Friday looks to remain dry as a surface high moves to the east and
upper level ridging begins to amplify over the eastern Plains.
Southerly returns flow kicks in for the later half of Friday, all
ahead of the next system.

This system comes in the form of a longwave, open upper low near the
U.S./Mexico border. This is, unfortunately, where forecast data
continue to show a decent amount of spread. It appears there is some
tightening in the data, suggest guidance may beginning to see a
solution more representative of reality come Saturday. As the upper
low closes in from the west, vorticity stretch well east of the
upper system, focusing near the MO/AR border. LREF data have shown a
broad area south of I-70, south into central AR, where QPF spreads
between the IQR are over an inch (0.10-1.25+). This is a product
of the placement of an west/east arm upper vorticity (mid/upper
ascent), coinciding with convergence at the nose of a 40-45 kt
LLJ. As the system rotates through, widespread rainfall looks
likely (60+ percent south of I-70) Saturday afternoon into early
Sunday morning.

Upper level ridging amplifies to our west early next week,
signaling the potential for yet another warm-up.


Maples

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1103 AM CST Tue Feb 10 2026

VFR conditions are expected throughout the 18Z TAF period. Breezy
north northwest winds are expected the remainder of the afternoon
behind a passing cold front, with decreasing speeds this evening
and overnight. Light north-northwest winds will then persist the
remainder of the period.

BRC

&&

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

$$

WFO LSX