Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

699
FXUS63 KLSX 101959
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
159 PM CST Sat Jan 10 2026

.KEY MESSAGES...

- A sharp cold front will bring gusty northwest winds and a brief
  period of showers this evening. Rain may transition to snow
  briefly, and while accumulations are not likely, brief
  visibility reductions are possible across mainly northeast
  Missouri and central Illinois.

- Gusty winds continue overnight, with occasional snow flurries
  possible.

- While Sunday will be chilly, a brief warmup is expected Monday
  and Tuesday before an extended cooling trend Wednesday onward.
  Precipitation chances are minimal after today.

&&

.SHORT TERM...  (Through Late Sunday Night)
Issued at 156 PM CST Sat Jan 10 2026

The most pressing item of interest in the short term period
continues to be the arrival of a sharp reinforcing cold front later
this evening, which is expected to bring a narrow band of convective
rain and gusty winds into the area. Some of this rain may also
briefly transition to snow, particularly in northeast Missouri and
central Illinois, and while accumulations are not expected, a brief
period of visibility reductions is possible thanks to the gusty
wind.

A relatively quiet period of weather has settled into the area this
afternoon, as winds have begun to weaken and back slightly ahead of
the approaching cold front. Upstream surface observations indicate
that the front is currently moving through south-central Iowa, and
will reach northeast Missouri within the next couple of hours.
Behind the front, some light to moderate snow has already started to
develop, although this initial activity is likely to shift east and
into northern and north-central Illinois.

However, as the front pushes south, a narrow band of convective
showers appears likely to develop along the boundary, which is
supported by an atmospheric profile featuring a deep layer of steep
lapse rates and mid-level saturation. Much of this initial
precipitation is likely to begin a rain considering the well above
freezing temperatures. However, temperatures will gradually cool
this evening, and this will likely be reinforced by evaporative
cooling as rain falls through a dry sub-cloud layer below 4-5000
feet. Surface wet-bulb temperatures are forecast to reach near the
freezing mark during the evening as this band moves through Illinois
and far eastern Missouri, supporting the potential for rain to
quickly transition to snow for a brief period. However, this is not
expected to last much more than an hour thanks to the quick forward
progression, and perpendicular orientation to the mean flow.

Meanwhile, this deep layer of steep lapse rates along and behind the
front is likely to extend to upwards of 750 to 800 mb, and will tap
into 40 to 50kt winds aloft. Between that and the potential for
evaporative cooling in the lower levels, it would not be surprising
to see some convectively-driven wind gusts approaching 45 mph for a
brief period. This combination of brief snow and strong wind gusts
may lead to very brief visibility reductions, but this is not likely
to last long, and the potential for this to impact travel is likely
to be higher just to our northeast in central Illinois. Still,
motorists should not be surprised to see a quick period of gusty
winds and snow for perhaps an hour or so later this evening.

After this line quickly moves through the area, winds may briefly
weaken before strengthening again by roughly midnight or slightly
sooner, with gusts approaching 30 to 40 mph through early morning.
Meanwhile, sporadic flurries or light snow showers may redevelop,
although this activity is not expected to be quite as robust as the
initial line earlier in the evening. Again, accumulations are not
expected in our area. Flurries/snow showers are expected to diminish
by roughly sunrise, and winds will gradually weaken through the day
as high pressure settles in.

Behind the front, seasonably cool temperatures will settle in
tomorrow, with morning lows in the 20s and afternoon highs reaching
seasonable values in the mid 30s to low 40s.


19

&&

.LONG TERM...  (Monday through Next Saturday)
Issued at 156 PM CST Sat Jan 10 2026

In spite of the persistence of northwest flow aloft, temperatures
are expected to quickly rebound Monday thanks to the resumption of
southwesterly low level flow and resulting warm air advection.
Temperatures are likely to climb by 10 to 15 degrees from the
previous day, and likely will reach well into the upper 40s to mid
50s with the warmest values in our southern Ozark areas. This trend
will continue Tuesday as well, with highs rising another 5 ish
degrees as low level winds increase slightly.

While this will lead to a more comfortable couple of days overall,
the most notable impact of this may a brief period of locally
elevated fire weather conditions on Tuesday. In addition to the
breezy southwest winds in the 10 to 20 mph range, NBM afternoon
humidity forecasts remain in the 30 to 40% range across the Ozarks,
and this may not be adequately capturing the effect of downslope
warming/drying across the Ozarks. Still, these conditions are on the
fringes of our criteria for elevated fire weather, and there isn`t
very much overlap between the strongest winds and lowest humidity at
this time. Not only that, but it is doubtful that most fuels aside
from grass and leaf litter will sufficiently dry by then to support
a more significant fire weather threat.

Tuesday night, confidence continues to increase that a shortwave
pivoting around the larger eastern U.S. trough will drive a
substantial cold front into the area. This is expected to kick off
an extended cooling trend that is likely to last through the end of
the week, thanks to persistent northwest flow and another
reinforcing front Friday. The current ensemble temperature forecast
envelope suggests that this mid-week cold surge is not likely to
feature temperatures far from seasonal averages, and there are also
hints that we may even rebound slightly Friday thanks to a brief
period of southwest flow. This is highly uncertain considering that,
as previously mentioned, another cold front may be arriving sometime
during the day Friday, and this front has at least some potential to
bring even colder air into the area over the weekend.

Meanwhile, precipitation chances remain minimal for the next week,
aside from what we`re likely to see today. There remain some hints
of light precipitation associated with the cold fronts Tuesday night
and late in the week, but probabilities remain low (20% or less) for
accumulations overall.


19

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1118 AM CST Sat Jan 10 2026

While VFR flight categories will prevail for a majority of the 18Z
TAF period, there are a few potential aviation hazards to discuss.

First, while skies are gradually improving, pesky stratocumulus
may continue to produce MVFR flight conditions at the start of the
period. Skies will clear shortly thereafter, and VFR conditions
are expected for a few hours this afternoon.

Between late afternoon and late evening, a sharp cold front will
push through the area, bringing a surge in northwesterly winds and
a brief round of showers. Gust speeds may briefly touch 30 to 40kt
as this occurs. Rain may also briefly transition to snow at
STL/SUS/CPS/UIN, which has a low (less than 30%) potential to
cause visibility restrictions for an hour or so as well.

Behind this line of showers, winds may weaken slightly, but
another round of increasing winds is likely overnight through
early tomorrow morning. Some additional light snow flurries will
also be possible overnight, but accumulations and VIS/CIG
category reductions are not currently expected.

BRC

&&

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

$$

WFO LSX