Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 270459

1059 PM CST Fri Dec 26 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 833 PM CST Fri Dec 26 2014

Scattered showers developing and streaming northeast from the
Ozarks this evening. Have adjusted POPs based on latest radar
trends. Some indication by the new NAM that rain will come to an
end earlier tomorrow than is currently forecast. Will wait to see
the GFS and if trend is same - may speed up departure of rain
behind the front.


.LONG TERM: (Monday through Next Friday)
Issued at 329 PM CST Fri Dec 26 2014

There is relatively good agreement in the global models in that a
positively tilted mean trough will stay established through at
least the first half of next week from central Canada into the
western CONUS. This will keep a relatively fast zonal flow over
MO/IL through most of the period. A large area of surface high
pressure will move under the zonal flow with no real notable
shortwaves troughs that would offer any precipitation chances at
least through Thursday. Model discrepancies show up by Friday as
the operational GFS is faster than it`s own ensemble mean in
ejecting the main upper low out of the southwest toward the
Midwest. While this is faster than the rest of the models, even
the ECMWF is showing precipitation developing over the area in a
broad warm air advection regime ahead of it bringing the upper low
through the area on Saturday. So with this said will go ahead and
introduce snow with some rain to the forecast on Friday.

Cold front will pass through the area on Monday and temperatures
will fall below normal on Tuesday and Wednesday before returning to
near normal for the start of a new year late in the week.



.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1043 PM CST Fri Dec 26 2014
Area of light rain should exit the KSTL metro area by around 08Z,
with only occaisional sprinkles thereafter through the night. MVFR
ceilings should hold through the night and into the morning on
Saturday at all TAF sites. Ceilings will gradually start to lift
to VFR range by mid morning at KUIN, then at KSTL by mid
afternoon. Cold front will reach KCOU by around 12Z, and KSTL by
around 16Z with winds veering to 280 degrees behind the front.

Specifics for KSTL: Main area of light rain should exit KSTL TAF
site by around 08Z. Only isolated very light showers or sprinkles
are expected for the remainder of the night. MVFR ceilings will
last through the night and into early afternoon on Saturday, then
gradually lift to VFR range before sunset. Ahead of an
approaching cold front, winds will veer to 230 degrees around 14Z,
then to 280 degrees after frontal passage around 16Z.





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