Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 160930
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
330 AM CST Tue Dec 16 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 326 AM CST Tue Dec 16 2014

Surface low currently over Quad Cities and will continue to lift
northeast today away from forecast area. Some lingering light
rain/drizzle to persist in wrap around this morning, mainly along
and east of Mississippi River. Otherwise, sc deck to be very slow to
move out of region, as high RH at 925mb remains entrenched over
forecast area today. As for temperatures, colder air to filter in
with temps still dropping a little this morning before becoming
steady or rise a few degrees by the early afternoon hours.

Byrd

.LONG TERM:  (Tonight through Monday)
Issued at 326 AM CST Tue Dec 16 2014

It will remain mostly cloudy tonight with lows in the 20s. On
Wednesday we remain under surface ridge with partly cloudy skies and
highs in the mid 30s to low 40s.

Then the forecast for Wednesday night through Thursday is still
tricky to pin down. Surface ridge moves off to the east with upper
trof developing over southwestern US. Will see pieces of energy
eject out of trof and track through forecast area Wednesday night
and Thursday. We will remain in cold air so any precipitation that
does develop with these shortwaves will be in the form of light snow
for most of the area. QPF amounts will be on the light side with
highest amounts over southern sections of our forecast area. Could
see a few tenths of snowfall with highest amounts south of a
Columbia to Fredericktown line.

Beyond that, extended models still have differing solutions on
system that will remain south of forecast area Friday through
Saturday. GFS is a bit further north then ECMWF. For now will not
make major changes to pops through this period. As for pcpn type,
will cold air in place, should be all light snow.

Byrd
&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1140 PM CST Mon Dec 15 2014

Gusty southwest flow behind the cold front and mostly low end
MVFR ceilings will prevail for the rest of the night. IFR flight
conditions will prevail across northern Missouri and west central
Illinois. Additionally, isolated to widely scattered showers will
pop on and off primarily north of I-70 for much of the remainder
of the night. Should see ceilings improve slowly through the
morning into early afternoon, though current thinking is that
heights will not get above 3000FT. MVFR ceilings may dissipate
and/or move east of the region Tuesday night according to some
guidance, but others keep MVFR ceilings through Tuesday night.
Think the conservative approach is warranted at this time so will
keep ceilings between 2000-3000FT in terminal forecasts for
Tuesday evening. Gusty southwest flow will veer to the west by
early Tuesday morning and continue to veer to the northwest by
Tuesday afternoon.

Specifics for KSTL:

Ceilings between 1000-1500 ft are expected to prevail throughout
the perdawn hours with an isolated shower or two possible, tho
expect most of the precipitation to fall north of the terminal.
Some guidance suggests that ceilings could drop below 1000FT
before 12Z Tuesday morning. While I cannot rule this out present
indications are that the lower ceilings should stay north of the
terminal. Should see ceilings improve slowly through the morning
into early afternoon, though current thinking is that heights will
not get above 3000FT. MVFR ceilings may dissipate and/or move east
of the region Tuesday night according to some guidance, but others
keep MVFR ceilings through Tuesday night. Think the conservative
approach is warranted at this time so will keep ceilings between
2000-3000FT in terminal forecasts for Tuesday evening. Gusty
southwest flow will veer to the west by early Tuesday morning and
continue to veer to the northwest by Tuesday afternoon.

Carney/Truett
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$
WFO LSX




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