Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 250508
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1108 PM CST Mon Nov 24 2014

.SHORT TERM:  (Through Tonight)
Issued at 209 PM CST Mon Nov 24 2014

Focus thru the period will be temps with no precip anticipated.

System will continue to move newd thru the period with large area of
cloud cover advecting s into the region. Mdls are in somewhat good
agreement keeping at least the nrn half of the CWA cloudy overnight.
The remainder of the CWA is more uncertain with pockets within cloud
deck that may open after sunset. Cloud cover will have a big impact
on temps tonight. Strong winds are also expected to linger longer
than prev anticipated, but gusts shud diminish by mid evening.

Taking this into consideration, have trended temps tonight slightly
warmer than prev forecast.

Tilly

.LONG TERM:  (Tuesday through Next Monday)
Issued at 304 PM CST Mon Nov 24 2014

(Tuesday through Thursday)

Latest models runs indicate the clipper that will move across
the area on Wednesday will be slightly deeper than previous runs
with slightly more QPF.  Have increased PoPs, particularly on
Wednesday, when the NAM and GFS show swath of decent ascent moving
across the CWA during the morning hours.  Precipitation type should
be mainly snow Tuesday night into Wednesday morning before low
level  temperatures warm during the afternoon.  Should be enough
moisture with this clipper for some minor snow accumulations over
northeast Missouri and west central Illinois.  Then the system will
quickly move out of the area leaving Wednesday night and Thursday
dry.

Stayed close to reasonable MOS guidance for temperatures which will
be below normal through Thursday.

(Friday through Monday)

GFS and ECMWF agree that upper pattern will be zonal through the
extended period with an upper trough approaching the area from the
west by next Monday.  Even with the current agreement with the upper
pattern and no big systems moving across the area, timing of weak
troughs can be difficult with zonal flow so there is some
uncertainty with this forecast. Then there is good agreement in both
models that a cold front will move southeast across the area on
Sunday night, though with zonal flow staying over the area the
coldest air will not move into the area. Both models are showing
some precipitation developing along this front over the area on
Sunday and Monday.  Still looks like low level flow will be
southwestly on Friday and Saturday with 850mb temperatures near +10C
on both models on Saturday.  This supports above normal temperatures
both days.

Britt

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1047 PM CST Mon Nov 24 2014

Low level clouds continue to rotate southeastward through
northeast MO and west central IL this evening, southwest of the
deep surface low just northeast of the Great Lakes region. These
clouds may remain just east northeast of COU late tonight, but
will continue to drop southeastward through UIN and may also move
through the St Louis metro area. There will be at least a brief
period of MVFR cloud heights in UIN, and also possibly in the St
Louis metro area as well. These low level clouds should completely
shift east of UIN and the St Louis metro area Tuesday morning.
W-nwly surface winds will weaken and lose the gustiness late
tonight as the surface pressure gradient relaxes. The surface wind
will back around to a swly direction Tuesday afternoon at UIN and
COU as the surface ridge axis shifts southeast of these taf
sites, and become light in the St Louis metro area Tuesday
evening.

Specifics for KSTL: Low level clouds across northern MO may advect
southeastward into STL late tonight with a brief period of MVFR
cigs possible. These clouds will shift east of STL by Tuesday
morning. W-nwly surface wind will weaken to around 8 kts late
tonight, then become light early Tuesday evening.

GKS

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     28  39  30  42 /   0   5   5  50
Quincy          22  35  25  38 /   5   5  10  60
Columbia        23  39  28  42 /   0   0  30  40
Jefferson City  24  40  27  43 /   0   0  20  30
Salem           27  37  25  41 /   5   5   0  50
Farmington      26  41  26  44 /   0   0   5  40

&&

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

$$

WFO LSX





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