Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

481
FXUS63 KLSX 242256
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
456 PM CST Tue Feb 24 2026

.KEY MESSAGES...

- Seasonable temperatures continue the next few days before a warm
  up ends the work week.

- A cold front this weekend brings a shift back toward cooler
  temperatures with another chance of precipitation early next
  week.


&&

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 147 PM CST Tue Feb 24 2026

Western ridging and eastern troughing has left the center of the
country in northwesterly flow aloft today. Some version of this
general pattern continues through the upcoming week with minor
variations affecting the day to day weather. A wave embedded in the
northwest flow is moving through the Upper Midwest this afternoon
with the surface low moving near Lake Superior. A cold front trails
this low to the southwest and will push southeast through our region
tonight. Ahead of the front, southwesterly flow has brought a warm
up, but tonight`s front will stunt that warm up. We only get a
peripheral shot from this cool air mass with barely noticeable
impacts on temperatures for most and a slight cool down in the north
for Wednesday.

The next wave in the northwest flow tracks out of the Northern
Rockies on Wednesday and through the mid Mississippi Valley
Wednesday night. This fast moving, weak wave brings with it the
chance of some light precipitation. Forcing is weak and the moisture
to the south remains cut off until the wave passes by our region to
the southeast. So while we do have fairly high precipitation chances
in the forecast, we`re mainly looking at a quick hitting light
precipitation event. There is just enough cold air on the northern
side of this wave that some of this could fall as snow, but ground
and near surface air temperatures will be too mild for any
significant impacts even if it does fall as snow. Less than 30
percent of 00Z low resolution ensemble members produce 0.1 inch or
more of liquid equivalent precipitation and among the high
resolution members that percentage is near zero.

Kimble

&&

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 147 PM CST Tue Feb 24 2026

After Wednesday night`s wave the surface high moves quickly east
through the southern Great Lakes leaving us with yet another
peripheral shot of briefly cooler air for Thursday. But as the high
moves east and return southerly flow begins we see a rapid warm up
for Friday. The entire region warms into the 60s, with the potential
for some 70s as well. NBM probability of 70+ rises to 40 to 70
percent across much of Missouri on Friday. That warmth continues
until our next cold front arrives on Saturday. This front is being
driven by a more robust wave tracking through southern Canada and
the air behind this cold front has much more cold potential with it.
The uncertainty for Saturday revolves around the timing of this
front and just how far south it pushes. Ahead of the front it`s
another day of warming, with even more widespread 70 degree warmth.
Behind the front, though, lurks a much colder air mass dropping
south out of the Canadian Arctic. The core of this cold air mass is
expected to push primarily to the east across the Great Lakes giving
us yet another glancing blow. While we aren`t talking extreme cold
like we saw earlier this winter, the air behind this front will push
temperatures back below freezing especially across our northern
forecast area. This sets the stage for our next round of potential
precipitation.

The next shortwave trough moves across the central US on Sunday
bringing our next chance of significant precipitation Sunday into
Monday. Although we will have seen multiple fronts push south
through our area over the preceding several days, these fronts never
clear the Gulf. As a result, moisture continues to build to the
south and by this weekend there will be a strong contrast between
increasing moisture on the warm side of the front and anomalous cold
to the north of it. There`s strong confidence that our area will be
behind the cold front by Sunday when this next shortwave trough
moves by and begins to tap into the available moisture just to the
south. So we will have to consider the potential for wintry
precipitation with this one Sunday into Monday.

First, the overall synoptic situation is one featuring warm, moist
advection into a retreating cold air mass. In this respect, it`s not
too dissimilar from the precipitation our region saw way back on
November 29. Warm advection would have the tendency to push
temperatures higher with time, but there is the potential for wintry
precipitation before the temperature warms above freezing. I do say
wintry precipitation because although snow or rain is favored, warm
advection scenarios do come with the potential for setting up
temperature inversions that could lead to transitional types such as
sleet and freezing rain. At this time range (Day 6) it`s rare to
have confidence on the temperature profile and thus the resulting
precipitation type, but all types would be feasible in this
scenario. Among the 12Z low resolution ensemble guidance, about 70
percent of members produce precipitation across our region in the 24
hours ending Monday morning and 60 percent produce at least some
snow along and north of Interstate 70. Among the GEFS members only,
up to 30 percent generate at least some freezing rain.

As far as potential amounts go, warm advection with anomalous
moisture available does have the potential to produce more
substantial precipitation amounts, particularly in areas of strong
frontal forcing. But it`s still unclear at this range whether each
of those variables (moisture and forcing) will line up at all and if
so where. Among the 12Z guidance, about 30 percent of members
produce 0.25 inch or more, while 10 percent produce more than 0.5
inch. It`s unclear at this point how much of this would fall as
wintry precipitation before a potential warm up.

Kimble

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 450 PM CST Tue Feb 24 2026

VFR conditions are expected throughout the 00Z TAF period. Gusty
southwest winds are expected to weaken near the beginning of the
period, and will become light and variable overnight as a weak
cold front sinks into the area. A very brief period of marginal
LLWS will also be possible this evening as winds weaken, but much
will depend on how quickly surface winds diminish. Either way,
confidence remains too low to mention at this time.

High level cloud cover will persist throughout the period, and
will be reinforced near the end of the period as a round of light
rain approaches from the northwest. While most terminals will
remain dry by 00Z Thursday, STL may begin to see some light rain
prior to 06Z.

BRC

&&

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

$$

WFO LSX