Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

288
FXUS63 KLSX 220948
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
448 AM CDT Mon Jun 22 2026

.KEY MESSAGES...

- Seasonably cool conditions are forecast this work week.

- A 30-60% chance of showers and thunderstorms is forecast from
  Wednesday into Wednesday night.


&&

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 209 AM CDT Mon Jun 22 2026

A seasonably cool airmass has settled into the area early this
morning thanks to continued low-level CAA behind a departing cold
front, that is now pushing into the Ohio River Valley. A rather
impressive field of 1-2kft stratus, for a summertime post-frontal
airmass, continues to filter into the area from the north. This
stratus is forecast to persist into the day today with gradual
scattering beginning late this morning into the evening from
northwest to southeast. With continued low-level CAA and limited
solar insolation, it will be a rather chilly day with winds around
10-15mph out of the north. Highs today will be in the 70s across the
entire area and may happen just before sunset. Given recent rainfall
across the area (saturated ground), potential clearing right before
sunset, and a surface high settling into the area overnight leading
to calm winds, there is the potential for fog. This potential
appears to be the greatest south/east of the STL metro since those
locations may clear around sunset, which would set the stage for fog
development early Tuesday morning. Confidence in this happening is
low (20%) for now, but the signal is certainly there. Broad
northwesterly flow aloft will encompass the Midwest through Tuesday,
leading to the continuation of unseasonably cool air and drier
conditions. Highs on Tuesday will be slightly warmer with greater
sunshine forecast, leading to highs in the upper 70s/lower 80s
Tuesday afternoon.

Peine

&&

.LONG TERM...  (Tuesday Night through Sunday)
Issued at 209 AM CDT Mon Jun 22 2026

Cooler than average temperatures are forecast for the entire week,
however, rainfall chances return to the area Wed/Wed night as a mid-
level shortwave traverses to the north near the US/Canadian border.
This feature will push a weak cold front towards the region with
>40% chances for 6hr accumulating precipitation across the entire
area. Both showers and thunderstorms are possible with these chances
as the LREF shows mean MUCAPE values of 1,000-2,000 J/kg (greatest
further south) across the area Wednesday afternoon/evening. From
Tuesday to the end of the week, highs will consistently be in the
upper 70s/lower 80s with lows ranging from the low/mid 60s, which is
about 5-10 degrees below climatological normals. This is supported
well by the LREF, which has narrow 3-5 degree temperature IQR spread
through Friday. By this weekend, long-range guidance indicates a
longwave trough moving to the western CONUS, potentially bringing
the return of more warm/humid conditions along with more chances for
showers and thunderstorms.

Peine

&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 448 AM CDT Mon Jun 22 2026

A large region of low MVFR/IFR stratus continues to pivot
cyclonically into the area from the north with northerly surface
winds around 10kts and intermittent gusts to 20kts. Uncertainty
still exists with the estimated timing of improving ceilings today
as the high sun angle should be efficient at eroding the stratus.
However, guidance is still indicating that conditions will be slow
to improve with return to VFR flight conditions sometime later this
afternoon. Northerly surface winds continue today with light and
variable winds starting after sunset tonight as a surface high
slides into the area from the north.

Peine

&&

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

$$

WFO LSX