Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 191747
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1247 PM CDT Fri Sep 19 2014

.SHORT TERM: (Through Tonight)
Issued at 300 AM CDT Fri Sep 19 2014

Large area of sfc high pressure will move from the Grt Lks to off
the NE coast with the ridge axis extending thru the OH Rvr Vly and
then into the sthrn Plains. The morning should start off with
some patchy fog, especially across cntrl and SE MO, which should
burn off by mid mrng. There will also be some scattered stratus
floating around, again esp across MO. Stratus, transitioning to
scttrd stratocu should persist thru the day. Friday should be a
few degrees warmer than Thursday. Low to mid 850 mb temps in the
low/mid teens support high temps in the upper 70s to lower 80s.
the placement of the ridge axis should limit the amount of low
level moisture return on the backside of the sfc high as it slides
off the coast.

2%

.LONG TERM: (Saturday through Thursday)
Issued at 300 AM CDT Fri Sep 19 2014

Energy that came ashore in the Pacific NW yesterday is fcst to
flatten the ridge across the Plains today and then dig SE thru the
wknd. This will drive a cold front thru the CWA late Saturday into
Saturday night. Temps in advance of the front are expected to be a
few degrees warmer than today which puts them above normal in the
low/mid 80s. At least scttrd SHRAs/TSTMs are expected to dvlp
along the front during the aftn and then continue thru the aftn
and into the overnight hrs as the front slides thru the CWA. The
front should clear the sthrn zones a few hrs shortly after
midnight. Any lingering precip should move out of our sthrn zones
Sunday mrng with drier air filtering in as another strong area of
high pressure assumes control. A secondary short wave will dig
down the back side of the trough on Sunday. The majority of the
dynamics pass well to the NE of the CWA but if this feature tracks
further to the SW, then an increase in cloud cover will be needed
with the possibility of adding mentionable POPs. the region
remains on the SW fringe of NW flow thru Monday. By then the
trough will have progressed to the east coast.

The remainder of the week is expected to be quiet with a persistent
500mb ridge across the Plains and large area of high pressure in
control of the majority of the eastern part of the CONUS. Temps
will slowly moderate thru the week while remaining in the 70s for
the most part for the rest of the week, which is near normal.

2%

&&

.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1237 PM CDT Fri Sep 19 2014

Ridge of high pressure extends southwest from the Ohio Valley
through east central Missouri into eastern Oklahoma. VFR flight
conditions will prevail this afternoon with scattered to broken
clouds around 4000 FT in parts of central and southeast Missouri.
Expect only a few clouds around 4000 FT elsewhere. VFR conditions
should continue to prevail tonight, except localized areas of
river fog which may reduce visibilities to IFR in some spots.
River valley fog should dissipate quickly after sunrise and VFR
conditions are expected to prevail Saturday morning.

Specifics for KSTL:

VFR flight conditions will prevail at Lambert at least through
Saturday morning. Wind will shift from the south the west-
southwest Saturday morning which will force a runway swap. There is
a slight chance of a thunderstorm Sunday afternoon ahead of a cold
front which will move through the area Saturday night, but
probabilities are too low to mention in the TAF at this time.

Carney

&&

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

$$

WFO LSX





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