464
FXUS63 KLSX 061725
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1125 AM CST Fri Mar 6 2026

.KEY MESSAGES...

- Visibilities will be reduced as low as one quarter mile over
  parts of eastern Missouri and west central and south central
  Illinois through 9 am this morning.

- Severe weather is possible from late this evening into early Saturday
  morning. Damaging winds and a tornado or two will be the
  primary threats if anything does become severe.

- There will be another chance of showers and thunderstorms
  Tuesday into Wednesday.


&&

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 350 AM CST Fri Mar 6 2026

We have already issued a Dense Fog Advisory until 9 am for much of
the eastern half of the CWA including the St. Louis metro area.
Surface observations and area webcams are showing reduced
visibilities. This is occurring along the warm front where winds
are relatively light, but visibilities should improve by mid
morning as this front moves north of the area.

Thunderstorms currently from eastern Kansas into north central
Missouri will continue to move northeast into northeast Missouri and
west central Illinois later this morning.  The RAP is showing low
level moisture convergence over this region through the day with
HREF probabilities between 50-70% while most of the rest of the CWA
will likely remain dry.  Highs today with warm air advection and
some sunshine will climb into the 75-80 degree range.

There is not much change in thinking about tonight`s severe weather
risk.  Severe thunderstorms are expected to develop this afternoon
and evening along a cold front over western Missouri and eastern
Kansas and eventually form into a line that the CAMS are showing
moving into the CWA late this evening or early overnight. This QLCS
will have the potential to produce some severe weather as it moves
into the CWA, with the HREF showing SBCAPE around 500 J/kg over
central MO, but these values will slowly decrease through the night.
There remains a few factors that may limit the potential for severe
weather late tonight including the CAMS consistently showing a pre-
frontal convection developing ahead of the QLCS which may use up
some of the instability.  In addition, forecast soundings are
showing a warm layer in the low levels which may limit extent and
severity of convection.  If the QLCS can survive, then brief
tornadoes are possible with the line segments along with damaging
winds and large hail.

The cold front will slowly move southeast across the area late
tonight into Saturday.  With this slow movement, there will continue
to be high chances (60-80%) for showers and thunderstorms over
southeast Missouri and southwest Illinois on Saturday morning with
scattered showers (30% chance) lasting into the afternoon.  With
winds turning out of the northwest, highs will be about 10 degrees
cooler than today.

Britt

&&

.LONG TERM...  (Saturday Night through Thursday)
Issued at 350 AM CST Fri Mar 6 2026

The LREF is showing the upper pattern becoming quasi-stationary late
in the weekend into next week.  The only notable system will be an
upper trough that will move through that central CONUS  by the
middle of next week.  There is some question about how much phasing
it will have with a southern stream system that will ultimately
determine its strength and timing, but for now there is chances for
rain from Monday night through Wednesday night with the highest PoPs
(70-90%) Tuesday through Wednesday.  The LREF joint probabilities
including SBCAPE and deep layer shear are supporting the potential
for a few strong storms on Tuesday.  Highs will climb back into the
70s on Monday and Tuesday before dropping back into the 50s and 60s
late next week.

Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1119 AM CST Fri Mar 6 2026

Mostly dry and VFR conditions will persist through today. Tonight,
showers and thunderstorms will overtake the CWA. Some severe is
possible with damaging winds, a brief tornado, and large hail all
potential hazards, especially in portions of central and northeast
MO. Timing reflects the best forecast we have now, but
thunderstorms may arrive more quickly or exit more slowly than
what`s in the TAF. MVFR conditions are expected with any
thunderstorm. MVFR ceilings are forecast to arrive behind the
thunderstorms lasting from mid-morning into the afternoon for most
locations. The cold front associated with these thunderstorms will
pass Saturday morning, ushering in westerly/west-northwesterly
winds behind it.

Jaja

&&

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

$$

WFO LSX