Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

592
FXUS63 KLSX 130851
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
251 AM CST Tue Jan 13 2026

.KEY MESSAGES...

- Unseasonably warm and dry conditions are expected to yield
  elevated fire conditions along/south of I-70 in Missouri this
  afternoon.

- Multiple cold fronts are expected to move through over the next
  4-5 days, with temperatures getting progressively colder behind
  each front.


&&

.SHORT TERM...  (Through Late Tonight)
Issued at 251 AM CST Tue Jan 13 2026

The latest surface analysis shows a cold front draped from the
Upper Midwest into the mid-Missouri Valley early this morning.
This front will continue to progress eastward through tonight,
moving into the lower Ohio Valley by 1200 UTC Wednesday. Our
region will be ahead of the front during the day today, with
continued low-level warm air advection. Temperatures at 850 hPa
peak just above 10C this afternoon in southwestern sections of the
area, or around the 95th percentile of climatology. Surface winds
are expected to veer ahead of the front. This is critical as a
west/southwest wind is ideal for downsloping off of the Ozark
Plateau. This should lead to enhanced warming across portions of
central, east central, and southeast Missouri. It is very
difficult to forecast warm enough temperatures with this type of
setup, so leaned toward the 90th percentile of the NBM for highs
today. For those areas detailed above which should experience the
most pronounced downsloping, leaned closer to the 95th percentile
where widespread low to mid 60s are forecast. Some spots may even
pop into the upper 60s. Further north, thicker cirrus should
arrive sooner, with cloud bases lowering gradually during the day.
Highs in the mid to upper 50s are forecast further north as a
result. Today`s highs at all three climate stations may threaten
daily records for the date (KSTL: 67-1952, KCOU: 66-1952, and
KUIN:
58-1932). Of the three official climate sites, St. Louis appears to
be the most prone to potentially tying or just breaking their
record.

Precipitation chances are expected to increase this evening as
surface convergence increases along the front, a weak midlevel
vorticity maxima moves through the region, and divergence
strengthens beneath the right-entrance region of an upper-level jet
streak. There is plenty of antecedent dry air, but the forcing
appears deep and long enough to produce an area of light rain. The
best chances (40-60%) are south of I-70/I-64 in Missouri/Illinois
respectively. Any rain that does fall tonight does look very light
however, with amounts under a tenth of an inch expected.


Gosselin

&&

.LONG TERM...  (Wednesday through Monday)
Issued at 251 AM CST Tue Jan 13 2026

(Wednesday - Friday)

Low-level cold air advection strengthens Wednesday morning, and
peaks early afternoon. This is a strong indicator for falling
temperatures at least through the morning hours, with readings
dropping into the 30s. Decreasing clouds are expected though, with
plenty of sunshine by mid-late afternoon. This should help
temperatures level off by afternoon. Seasonably cold conditions are
forecast Wednesday night, with a surface ridge moving into
central/northeast Missouri by 1200 UTC Thursday. The combination of
a clear sky, low dewpoints (<25th percentile), and slackening winds
should lead to favorable conditions for radiational cooling. This
will be most pronounced in central/northeast Missouri based on the
expected timing of the surface ridge axis. Widespread teens are
forecast, or 5-10 degrees below normal for the date and the coldest
so far within the month of January.

Seasonably cold temperatures will continue into Thursday as the
surface ridge moves across the mid-Mississippi Valley. Highs in the
30s are expected along with increasing cloudiness. The combination
of increasing low-level warm/moist advection and an approaching cold
front may produce some light snow along/east of the Mississippi
River Thursday night. The biggest limiting factor once again is
plenty of low/mid level dry air, but forcing for ascent may just be
strong enough for some light snow. The best chances (20-30%) are in
parts of western and south-central Illinois. There are some subtle
timing differences with the front along with some spread in where
the low-level warm/moist advection will be strongest. This is why
PoPs from the NBM may be a bit artificially too low. The latest LREF
shows 6-hr probabilities for measurable snowfall peaking in the 60-
80% range along/east of the Mississippi River. As these differences
mentioned above are likely to decrease over the next 24-36 hours,
PoPs likely will increase unless the area of stronger low-level
warm/moist advection were to shift further to the northeast and out
of the region.

A modest warmup is expected on Friday as the air mass behind the
preceding cold front has its origins from the Pacific Ocean. Highs
mainly in the 40s are expected across the region.


(Friday Night - Monday)

The next cold front that moves through however Friday night is
arctic in nature, coming originally from Alaska. With the source
region (Alaska) expected to see minimum temperatures of -40 to -50F
over the next 24-48 hours, this incoming air mass should mean
business. As mentioned yesterday, a lack of local and upstream snow
cover will help take the edge off of the cold so to speak, helping
to modify the air mass as it plunges southward into the mid-
Mississippi Valley this weekend. It still looks unseasonably cold
however, as mean 850-hPa temperatures on the LREF drop to near -20C
(~1st percentile of climatology) Saturday evening. There is some
lingering uncertainty as to which day this weekend will be the
colder of the two, namely due to subtle differences with the timing
of the heart of the arctic air mass. The spread in high temperatures
is especially large on Sunday, with IQR ranges on the NBM as high as
20-25+ degrees. Saturday has much lower spread, closer to 10
degrees. What is more certain is that at least one of these days
should see high temperatures staying in the 20s, but it could be
both or just one or the other. Low temperatures are a similar story,
with large spreads in the IQR due to differences in timing the
surface anticyclone. One morning is likely to get down into the
single digits, most likely Sunday. These temperatures combined with
brisk northwest winds may cause wind chill values to drop into the 0
to -10F range. There is quite a bit of uncertainty though due to
differences with the timing of the arctic air mass. LREF
probabilities for below zero wind chill values have increased
compared to yesterday for Sunday morning, now in the 40-70% range.
For below -10F, chances range from 20-40%.

Ensemble guidance has come into better agreement that another arctic
front will pass through the region sometime early next week. This
should lead to a warmup ahead of this front, but how warm is an open
question. This incoming air mass could rival its predecessor, but
there is uncertainty not only where this air mass will head, but
also its magnitude. Our region may be on the southwestern edge, and
there is a big difference between the much colder EPS vs. the
"warmer" (but still cold for January) GEFS.

Precipitation wise, anything that does fall during this time period
is very likely to be snow. There still appears to be multiple
chances of light snow, one Friday night associated with the initial
arctic frontal passage, and continued chances on Saturday beneath
the cyclonic flow aloft. Any snow that does fall should be very
light, but the LREF shows 24-hr probabilities of measurable ending
0Z Sunday of 50-70% from west to east. Chances for 1+" drop below
15% however. Similar to Thursday night, forecast PoPs are likely to
climb in the coming days as forecast uncertainty decreases.


Gosselin

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 950 PM CST Mon Jan 12 2026

VFR flight conditions and southwest to westerly flow is expected
to prevail into Tuesday afternoon. Low level wind shear will
increase over the next few hours and persist into Tuesday morning due
to a strengthening low level jet. LLWS will decrease Tuesday
morning as daytime heating mixes out the nighttime inversion. Wind
gusts will then increase to around 20-25kts. Ceilings are expected
to lower Tuesday evening to 4000-7000ft with a chance for some
light rain developing after 01-02Z.

Carney

&&

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

$$

WFO LSX