Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

228
FXUS63 KLSX 190358
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
958 PM CST Wed Feb 18 2026

.KEY MESSAGES...

-A Red Flag Warning has been issued for Thursday across southeast,
central, and northeast Missouri from noon to 8PM.

-A few severe thunderstorms are possible Thursday afternoon and
evening, largely along and east of the Mississippi River. Tornadoes
and damaging winds are the main threats.

-A cold front will move through Thursday evening, bringing cooler
 temperatures back to the region through the weekend.


&&

.SHORT TERM...  (Through Late Thursday Night)
Issued at 241 PM CST Wed Feb 18 2026

Temperatures have warmed into the 60s across much of the forecast
area, even pushing 70F across portions of southeast and east-central
Missouri, under a clear sky and with deep mixing. The next system is
starting to form along the lee side of the middle Rockies, and will
progress eastward overnight and into tomorrow morning. The surface
low will bring two boundaries through the area Thursday afternoon
and evening, as well as a slight chance for severe weather.

The first boundary will be a dryline that will move through the
area during the afternoon. The best shear, moisture, and
instability will pool ahead of the dryline. Confidence is high
this will happen across southern Missouri and areas east, given
the timing of the dryline moving through Missouri during the
morning, and into Illinois during the afternoon. Convective
initiation is expected to start across eastern Missouri during the
late morning while this region is still within the moist warm
sector, but the severe potential will be quiet limited. Marginal
instability (around 100 J/kg of SBCAPE) and strong 0-6 km shear
(60-80 kts) may be enough to produce a strong to severe storm or
two, but the instability is likely too weak to balance the intense
shear. If any storms do become strong to severe, elevated hail
producing storms are most likely.

The severe potential increases during the afternoon as warm sector
convection moves into southern Illinois and the best environment.
Here, the HREF is indicating 250-500 J/kg of SBCAPE will be
available and soundings indicating that convection will be surface-
based in Illinois during the afternoon. This will be enough
instability to generate a few severe thunderstorms given the strong
0-6 km shear (60-80 kts). Winds will be slightly more backed ahead
of the dryline than behind it, resulting in better 0-1 SRH, and
hodographs with better low level curvature than compared to
yesterday. Tornadoes, hail, and damaging winds are all possible with
any storms that become severe in Illinois. The dryline will exit the
forecast area during the early evening, between 6-8 PM and
convection will follow suit.

Humidity will drop behind the dryline through the entire day,
starting during the late morning for portions of northeast, central,
and southeast Missouri. Southwesterly flow and deep mixing behind
the dryline will encourage locally warmer and drier conditions than
model guidance typically illustrates, thus I have used some of the
extremes of the guidance suite for humidity and temperatures
tomorrow. The result will be Red Flag conditions across the area
outlined above, and more can be read in the Fire Weather Planning
Forecast. Needless to say, don`t burn tomorrow.

Later in the evening/overnight hours the actual cold front
associated with this surface low will push through the forecast
area, bringing a surge of cooler air to the region.

Delia

&&

.LONG TERM...  (Friday through Next Wednesday)
Issued at 241 PM CST Wed Feb 18 2026

Great attention was paid to the short term forecast today, but a
cursory glance at the extended guidance shows little change from
previous forecasts. The weekend continues to trend drier as a
surface boundary stalls over the Deep South, cutting off moisture
return to the mid-Mississippi Valley. Otherwise conditions will
start to cool Friday, but the main thrust of cold air will move into
the forecast area Saturday-Monday under deep northwesterly flow,
returning the region to near to below normal temperatures. Ensemble
guidance continues to highlight a warming trend that will start
Tuesday as the low-level ridge builds in a few steps ahead of the
advancing mid-level ridge, bringing warm air advection and above
normal temperatures back to the region for the remainder of the
period.

Delia

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 958 PM CST Wed Feb 18 2026

Dry and VFR flight conditions will prevail for most of the TAF
period outside of convection on Thursday. Some fog/low ceilings are
possible this morning as well, but model guidance has been more
consistent on this develop being across south-central and
southeastern IL, away from all terminals. Confidence is increasing
that a broken arc of showers and thunderstorms will eventually
develop during the morning and track eastward through the morning,
potential impacting all terminals. Currently, the chance of impacts
is highest at St. Louis metro terminals where a TEMPO (versus
PROB30) group has been introduced. Additional development during the
afternoon is much less clear and could end up being to the east and
northeast of all terminals. Otherwise, a dry line/front will advance
eastward through the area, veering winds to the southwest with
occasional gusts of 20 to 30 kt. Another front will arrive during
the evening, veering winds again to westerly.

Pfahler

&&

.CLIMATE...
Issued at 255 AM CST Wed Feb 18 2026

Daily record high temperatures may be threatened this week. Here
are record highs at our three official climate stations:

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


&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Red Flag Warning from noon to 8 PM CST Thursday for Audrain MO-
     Boone MO-Callaway MO-Cole MO-Crawford MO-Dent MO-Franklin
     MO-Gasconade MO-Iron MO-Knox MO-Moniteau MO-Monroe MO-Osage
     MO-Reynolds MO-Shelby MO-Washington MO.

IL...None.
&&

$$

WFO LSX