Chesterfield, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

612
FXUS63 KLSX 130400
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1000 PM CST Tue Nov 12 2024

.KEY MESSAGES...

- Light rain will move through the area Wednesday, bringing less
  than 0.25" of rain to a majority the area.


&&

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 214 PM CST Tue Nov 12 2024

Mid-day water vapor imagery shows a deep mid-level trough across the
Inner-Mountain West. Over the remainder of the day and into the
evening the trough will eject eastward, and surface cyclogenesis
will develop a surface low over the Upper Plains in response. The
system will approach the mid-Mississippi Valley tomorrow, bringing
showers to the forecast area ahead of a west to east moving
surface front during the afternoon and into the evening. Moisture
convergence ahead of and along the front weakens with eastward
movement, and despite upper level support, results in relatively
light QPF across the area. The best location for higher rainfall
will be to the southeast of the forecast area where a low-level
jet will ramp up to provide significantly better moisture
convergence and lift.

The probability of over 0.25" of rain on Wednesday maximizes around
40-50% across far southeast Missouri and southwest Illinois, closest
to the axis of highest precipitation. The probability of 0.50" of
rain or more peaks around 20% in the same area, increasing
confidence that precipitation amounts will remain modest. A rumble
of thunder or two is possible during the afternoon as 100-300 J/kg
of instability slides northward along the Missouri-Illinois border.
Mainly though, this will produce more showery than stratiform
precipitation. Brief periods of drizzle will follow behind the front
as ascent becomes increasingly shallow.

The front will push through the area during the evening and clear
out any lingering rain and drizzle. Despite the wind shift the air
behind the front will be no cooler than ahead of it. In fact, the
heavy cloud cover will help keep temperatures a few degrees
warmer Wednesday night than tonight.

Delia

&&

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 214 PM CST Tue Nov 12 2024

With the exit of the mid-level trough a ridge will build into the
central CONUS in it`s wake. This ridge will linger through the end
of the work week, and coupled with a large surface high will provide
a few days of dry weather. Temperatures will increase a few degrees
each day under a clearer sky and low-level warm air advection.

During the end of the work week a deep mid-level trough will move
onshore along the West Coast. All ensemble members show the trough
deepening and eventually developing into a split stream system over
the western CONUS by the end of the weekend. The northern stream
trough will slide through the Great Lakes Region, bringing a
weakening surface front into the forecast area during the end of the
weekend/start of the work week. This front may linger across the
area into the start of the work week, providing a focus for
precipitation as the synoptic pattern becomes more active beyond the
current forecast period.

Despite the multiple chances for precipitation, ensemble guidance
shows a trend of gradual warming above normal (mid to upper 50s)
through the period. Exactly how warm we get by the weekend and start
of next week remains uncertain (4-7 degree C interquartile spread)
as the location of the surface front and any associated
precipitation will have an impact on daily highs.

Delia

&&

.AVIATION...  (For the 06z TAFs through 06z Wednesday Night)
Issued at 951 PM CST Tue Nov 12 2024

VFR flight conditions are expected to prevail across the area
through late Wednesday morning/early afternoon. Low MVFR/IFR
ceilings as well as light to moderate rain will spread north and
east across the area through Wednesday afternoon as a storm
system moves from the eastern Plains into western Missouri and
Iowa. Guidance continues to suggest that the lowest flight
conditions will likely be across southeast Missouri into
southwest and south central Illinois during the afternoon and
evening where ceilings may fall below 500 ft AGL. Rain and fog is
also likely to reduce the visibility to less than 3SM. Rain will
clear the area from west to east through the evening and early
overnight hours. Isolated showers and/or areas of drizzle will
likely persist behind the steadier rain. Ceilings are likely to
improve somewhat to low MVFR, although the patchy drizzle may
continue to suppress visibilities.

Carney

&&

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

$$

WFO LSX