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FXUS63 KLSX 081148
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
548 AM CST Sat Nov 8 2025

.KEY MESSAGES...

- Temperatures Sunday through Tuesday morning will be some of the
  coldest so far this season before a warming trend starts Tuesday
  and continues through the end of the week.


&&

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 332 AM CST Sat Nov 8 2025

As of 3 AM the surface low associated with today`s system is moving
east across the Kansas-Nebraska border, while a cold front is draped
just north of I-70 across Missouri. Through the day a shortwave
associated with a broad mid-level trough will push through the
region, bringing the surface low across I-70 this afternoon and
evening. Both lift and moisture will be maximized on the northern
side of the surface low, resulting in the highest precipitation
totals along and north of the Iowa border. HREF guidance indicates a
70% chance of at least 0.10" of rain, and a 40% chance of at least
0.25" of rain across far northeast Missouri and west-central
Illinois. Thus, rainfall is not expected to be beneficial, though
slight changes in the track of this system could bring more rain and
higher totals into the northern CWA. Across a majority of the rest
of the forecast area rainfall amounts will be light, less than
0.10", and many south of I-70 won`t see any rain.

This system will exit the forecast area overnight, taking the best
chances for rain for the next 7 days with it. An anomalously strong
cold air mass (near the 1st percentile for this time of year) will
surge into the mid-Mississippi Valley in its wake, and stick around
through Tuesday morning. Temperatures will start off in the 30s
Sunday morning, and struggle to make it into the upper 30s north of
I-70, and the low 40s to the south of the interstate. These cold
surface temperatures and the robust cold air aloft mean that any
precipitation that is squeezed out of this cold, dry airmass on
Sunday by another mid-level shortwave will fall as snow or a rain-
snow mix. Confidence in this occurring is low due to the low level
dry air, but a few CAMs are showing a smattering of QPF Sunday
morning. No accumulations or impacts are expected.

Winds will pick up Saturday night into Sunday as the surface
pressure gradient tightens due to the anomalously strong incoming
high. Sustained winds in the upper teens with gusts into the 20s
will persist through Sunday afternoon. The wind will make it feel
roughly 10 degrees cooler than the measured air temperature during
this period.

Delia

&&

.LONG TERM...  (Sunday Night through Friday)
Issued at 332 AM CST Sat Nov 8 2025

The cold air will linger through Monday, with morning lows in the
upper teens to low twenties and highs near 40, despite a clear sky
and abundant sunshine. By Tuesday the mid-level trough will exit the
central CONUS, a ridge will develop over the West Coast, and
northwesterly flow will establish over the area as a result. In the
low-levels, westerly to southwesterly flow will kick start warm air
advection areawide on Tuesday, starting a warming trend that will
continue through next week. Mid-level northwesterly flow will
persist through much of the work week, keeping the region open to
shortwave disturbances. A lack of moisture return through the week
means that these disturbances will pass with little more than
increased cloud cover to mark them. By the end of the work week the
mid-level pattern begins to diverge as the mid-level ridge shifts
eastward from a trough advancing towards the west coast. The speed
at which this happens and the evolution of the West Coast trough
remain uncertain and will impact how warm the end of the work week
and next weekend will be.

Delia

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 543 AM CST Sat Nov 8 2025

High clouds have moved in over the forecast area overnight ahead
of an approaching weather system. As the system moves east through
the area it will bring rain to KUIN, with lesser chances at the
mid Missouri (KJEF, KCOU) and St. Louis metro (KSTL, KSUS, KCPS)
terminals. MVFR to fuel alternate ceilings will move in after the
rain and linger overnight before dry air moves into the region and
scours out the low cloud deck, returning terminals to VFR flight
conditions.

Winds will shift from southwesterly to northwesterly as the system
passes through, becoming gusty after the rain this evening. Winds
will remain elevated and gusty overnight and through the day
Sunday.

Delia

&&

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

$$

WFO LSX