Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

165
FXUS63 KLSX 171122
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
522 AM CST Wed Dec 17 2025

.KEY MESSAGES...

- Mild weather for mid December continues today. After a brief
  cool down Thursday into Friday, the mild weather returns
  again.

- The only significant rain chances come Thursday morning with a
  frontal passage.


&&

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 225 AM CST Wed Dec 17 2025

Although a weak front has dropped into the northern part of the
forecast area this morning, it`s already quite diffuse and will
continue to lose its definition and influence over our weather this
morning. After light winds this morning, they`ll become southerly
later today with afternoon temperatures as warm or warmer than
yesterday for most.

A trough moving onshore in the Pacific Northwest this morning will
dig a sharp trough into the Central Plains tonight and head to the
Great Lakes on Thursday. The result will be a stronger cold front
which brings a brief shot of colder air to our area. Ahead of the
front, Gulf moisture surges northward late tonight leading to warm
advection showers developing ahead of the front and light rain along
and behind it Thursday morning. There`s even the potential for just
enough instability to develop for a rumble or two of thunder,
although instability will be too limited for a severe weather
threat. We continue to expect strong winds behind the front, but
cold advection comes in two waves: the first Thursday morning and
again Thursday evening. This results in two bursts of greater mixing
in the cold advection, but perhaps less intense winds overall.
Greatest gusts are north of the Missouri River where 40 mph gusts
are possible.

Kimble

&&

.LONG TERM...  (Thursday Night through Tuesday)
Issued at 225 AM CST Wed Dec 17 2025

The cold peaks Thursday night into early Friday as high pressure
crests over the region. As the high moves east we already see warm
advection beginning even on Friday, with the full warm up felt by
Saturday when temperatures reach the 50s again. The probabilistic
NBM actually has chances of 60 degree readings approaching 50
percent south of the Missouri River.

Another cold front moves through late Saturday, but the core of the
cold air is driven eastward through the Great Lakes. So we only get
a glancing blow of cold from this one, not as intense as Thursday.
So expect a little cool down Sunday going into Monday, but it will
still be near or even above average for late December, in the 40s.
The NBM interquartile range for highs Sunday continues to shrink
reflecting growing confidence in this glancing blow rather than a
full thrust of cold. Early next week the warmer weather returns with
ridging becoming dominant aloft through around Christmas.

Kimble

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 519 AM CST Wed Dec 17 2025

VFR conditions continue today with light winds. Tonight, the
pressure gradient increases with a SSE wind increasing in
response. Moisture returns aloft eventually leading to MVFR
ceilings and rain by Thursday morning. With a low level inversion
and increasing winds aloft, the potential for low level wind
shear increases after midnight with winds aloft out of the SSW at
45KT. If low level mixing is greater, then surface winds will be
stronger but low level wind shear will be mitigated. However, with
a strong inversion expected, we`re erring on the side of low
level winds remaining lighter and out of the SSE with enough
chance of low level wind shear to include it in the TAFs.


Kimble

&&

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

$$

WFO LSX