Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

525
FXUS63 KLSX 162310
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
510 PM CST Mon Feb 16 2026

.KEY MESSAGES...

-Temperatures will continue to warm through Thursday, nearing
records on Wednesday.

-Showers and thunderstorms on Thursday will bring relatively
 cooler temperatures back to the region for next weekend.


&&

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 229 PM CST Mon Feb 16 2026

Strong warm air advection in the low levels has resulted in
seasonably warm conditions across the region this afternoon despite
the incoming high clouds. As of 2PM the entire forecast area has
popped above 60 degrees, with temperatures expected to warm an
additional few degrees between now and 3-4PM. High clouds overnight
and slightly elevated winds (around 5-7 mph) will help to keep
conditions mild, as well as reduce the risk for fog everywhere
expect in the most sheltered of river valleys.

Mid-level ridging will continue into Tuesday, though the axis of the
ridge will push eastward as a deep mid-level trough comes onshore
over the West Coast during the day. Warm air advection will continue
tomorrow under the mid-level ridge, pushing 850 mb temperatures near
their climatological maximum. Mixing will be too shallow to take
advantage of 100% of this warmth, and tomorrow`s highs will end up
being similar to a degree or two warmer than today`s. The surface
pressure gradient will tighten with the approach of a surface low
from the northwest, generating breezy conditions, making it feel
more like early May than mid February. This low will track eastward
with a shortwave within the broader mid-level trough, bringing a
Pacific front through the forecast area Tuesday night. Moisture
return ahead of this front isn`t particularly strong, through HREF
guidance indicates about a 20% chance of precipitation, particularly
across central and northeast Missouri. If rain does fall, it will be
light and nothing in comparison to what we saw this weekend.

Delia

&&

.LONG TERM...  (Wednesday through Next Monday)
Issued at 229 PM CST Mon Feb 16 2026

Conditions behind the front will be merely drier than ahead of it,
with no change to sensible temperature. Continued warm air advection
will push 850 mb temperatures into the mid teens (unusually warm for
this time of year). Mixing will be deep enough to access this
warmth, increasing temperatures from their already warm conditions
on Tuesday. Another surface low will form over the middle Rockies
Wednesday, resulting in southwesterly surface flow across the mid-
Mississippi Valley during the day. Adding to the already warm
conditions, the southwesterly flow off the Ozark Plateau will result
in warmer, drier conditions, adding several degrees onto an already
warm day. Resulting high temperatures on Wednesday will tango with
records at all three climate sites. There is a 70-100% chance for
high temperatures in areas along and south of I-70 to exceed 70F,
and portions of southeast Missouri have a 40-60% chance of exceeding
75F. Thursday will be another very warm day ahead of the passage of
the surface low. Temperatures will push into a similar range as
Wednesday, and while won`t challenge records, will be one of the
warmest days thus far in 2026.

The surface low will progress east through the forecast area
Thursday, bringing a cold front through the forecast area Thursday
evening. Ahead of the front, moisture and instability is expected to
surge north into the region, and combine with strong 0-6km shear (70-
80 kts) to increase the potential for severe thunderstorms.
Uncertainty exists in how far north and west the moisture and
instability make it, due in part to uncertainty in the timing of the
frontal passage on Thursday. An earlier frontal passage will result
in limited severe weather chances across our region, while a later
passage will allow for more instability to surge northward and
increase severe weather potential. Ensemble guidance is currently
favoring southern Illinois and areas east for the best overlap of
ingredients, but this could change in the coming days as the
previously mentioned details come into better focus.

Behind the front, cold air advection is expected to bring a cool
down, returning temperatures to near to slightly above normal. The
mid and low-level patterns diverge greatly during this period as the
mid-level trough progresses east through the central CONUS. There is
uncertainty in the movement and strength of various shortwaves
within the broader trough, resulting in uncertainty in precipitation
chances and temperatures. Confidence grows however that as the
trough exits the central CONUS during the second half of the
weekend, a mid-level ridge will build back into the region for the
end of the extended period. Nearly all ensemble guidance members
depict this, and CIPS analogs highlight warming temperatures during
the last week of February.

Delia

&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 503 PM CST Mon Feb 16 2026

Dry, VFR conditions will persist through the valid period at the
TAF sites, with the biggest impact coming from a strengthening
southerly wind of 15-20kts. There is a signal for IFR fog/low
stratus across the Ozarks and south-central Illinois tonight,
where a plume of higher surface relative humidity is forecast, but
this threat will stay far from the TAF sites.

MRB

&&

.CLIMATE...
Issued at 232 AM CST Sat Feb 14 2026

Daily record high temperatures may be threatened this week. Here
are records between Tuesday 2/17 and Thursday 2/19 at our three
official climate stations:

        Tuesday 2/17        Wednesday 2/18      Thursday 2/19
KSTL    77/1911             74/1971             77/2016
KCOU    74/2011             71/2017             77/2017
KUIN    72/2017             68/2017             72/2017

&&

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

$$

WFO LSX