Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 270429

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1129 PM CDT Wed Oct 26 2016

Issued at 942 PM CDT Wed Oct 26 2016

Cold front as of 0200 UTC was roughly along a KJEF to KPPQ line.
This front will continue to slide southeast and clear the CWA
around 0900 UTC. Along/ahead of this boundary...isolated showers
and sprinkles are possible. Winds behind the front will sharply
turn from the southwest to the north/northwest. Main change to the
previous forecast was to up cloud cover quite a bit overnight
tonight and into early Thursday morning. Widespread stratus
currently extends into southern Canada and as far west as the
Missouri River near the IA/NE border. 950-850 hPa winds are out of
the NNW so advection will be very slow from west to east over the
next 12-18 hours. Stratus should breakup by mid/late morning
holding off the longest on the IL side of the Mississippi River.
Other change from the previous forecast was to slightly boost
overnight lows up 1-3 degrees due to the aforementioned stratus.



.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 340 PM CDT Wed Oct 26 2016

Mesoscale vort center which has triggered showers and isolated
thunderstorms this afternoon will move east of the CWA by around 00Z
ending the threat of additional storms. Behind that feature...a cold
front will move through the CWA during the evening and reach the St.
Louis metro by around 06Z. There may be a few light showers along
the front...however insufficient CAPE should preclude additional
thunder. Winds will become northwest behind the front with a low
stratus deck moving in as well. Stratus will gradually clear from
west to east during the late morning and afternoon on Thursday.
Temperatures will be near seasonal normals on Thursday...with highs
in the low to mid 60s.


.LONG TERM...  (Thursday Night through Next Wednesday)
Issued at 340 PM CDT Wed Oct 26 2016

The current weather pattern indicates a warm and dry fcst thru early
next week.

Thursday night thru Friday

SW upper flow in place Thu night gradually becomes zonal Fri as a
chunk of energy is ejected from the West Coast trough. The short wave
comes onshore across the Pac NW Thu PM and then traverses the
US/Canadian border Fri. At the SFC...SFC ridge is already E of the
CWA by Thu night allowing return flow to be well established on Fri.
Thu night should be seasonable warm with lows temps 5-10 degrees
above avg due to a mild air mass in place and the sthrly flow. This
will set the stage for a warm Fri. Deep S/SW flow and 850 temps in
the mid/upper teens are basic ingredients to a warm day but the key
is how deep mixing will be. The NAM/Local WRF and SREF all indicate
mixing heights sloping from approx 925mb across sthrn IL to 875mb
across cntrl MO...but the GFS is considerably higher except across
sthrn IL. This should lead to highs ranging from near 70 for sthrn IL
to low and potentially mid 80s for cntrl MO. Another short wave is
kicked out of the base of the West Coast trough Fri.

Friday night thru Sunday night

Sthrly flow will keep up Fri night as the initial short wave slides
SE into the Grt Lks. This feature will drag a cold front into the
nthrn FA Sat mrng. Since the short wave is fcst to pass well N of
the FA...the bndry doesn`t have a whole lot of drive to push it S so
it is expected to slowly sinks S thru the day reaching along or just
N of I70 by Sat night. FROPA appears to be dry attm. The next short
wave approaches the region late Sat night into Sun mrng. The vort
assocd with this feature generates a bit of precip but the bulk of
this activity remains NE of the CWA as the short wave passes by.
This feature helps push the bndry a little farther S by Sun
evng...taking it S of the MO Rvr. The bulk of the West Coast trough
comes onshore a result... upper level ridging begins to
work into the area Sun PM. Solutions for the wknd have shifted
considerably over the past several days so I would think there will
continue to be addtnl adjustments as guidance tries to fine tune the

Sat should be another warm day...esp for locations that remain S of
the bndry thru a good portion of the aftn. 850mb temps remain in the
mid/upper teens and would expect maybe even a little better
mixing out ahead of the advancing cold front which should lead to
another day with widespread 70s with a few lower 80s. Even with a
bndry that is expected to be S of the majority of the CWA by Sun
aftn...Sun is expected to be another day with above avg temps with
highs in the upper 60s to mid 70s from N to the same time
being possibly the coolest day thru the middle of next week.

Monday thru Wed

Upper flow turns SWrly in advance of the main short wave. The wknd
cold front will lift back north as a warm from reestablishing deep
sthrly flow thru the day setting the stage for yet another day with
much above normal temps. 850mb temps are once again in the mid/upper
teens...though the 850 thermal ridge is centered N of the FA. The GFS
and ECMWF have timing differences with the main short wave energy.
The GFS is about 6-12 hrs faster than the ECMWF. The GFS drags a
cold front thru the CWA Mon night whereas the ECMWF has the cold
front entering the nthrn CWA Tue mrng. The ECMWF solution stalls the
bndry approx along I70 Tue PM and then washes the front out
overnight. Regardless of the would appear that the
pattern of dry FROPAs will continue. Depending on the eventual
timing of the Tue cold front...Tue could be another warm day for at
least a portion of the area.  A SFC ridge passes N of the area Tue
into Wed allowing return flow to begin again by late Tue night. Wed
could very well be yet another day of aoa normal temps.



.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1121 PM CDT Wed Oct 26 2016

Cold front is currently nearing KSUS and KSTL as of 0400 UTC and
should be through those terminals within the hour. Frontal passage
at KCPS looks to be between 0500 and 0600 UTC. Behind this
front...expect NNW winds of 10-15 mph overnight tonight. Main
story however will be on stratus. Ceilings of around 1500 feet AGL
are expected to persist through the morning hours before
scattering out from late morning to early afternoon from west to
east. This is about 3-5 hours slower than the previous TAF. Delay
was mainly due to the widespread coverage to the northwest and the
time of year. In addition...0000 UTC models have finally caught up
with what is actually going on currently. A mostly clear sky is
expected by late Thursday afternoon with light/variable winds as
the sfc ridge comes across the bi-state region.


Cold front just on the doorstep of Lambert Field as of 0400 UTC
and should be through by 0500 UTC. Winds will sharply turn to the
NNW behind the front with speeds between 10 and 15 mph. MVFR
celings with bases around 1500 feet AGL will be the rule for the
rest of tonight and into very early Thursday afternoon. Slow
improvement in ceilings this time of year in part due to low solar
angle. By late afternoon expect a mostly clear sky with
light/variable winds due to surface ridge coming across the mid-
Mississippi Valley.



Issued at 340 PM CDT Wed Oct 26 2016

With an upcoming stretch of unseasonable warmth expected over the
weekend, here is a list of record high temperatures thru the weekend.
Although there are no record high temperatures in the forecast just
yet, stay tuned to the forecast as that could change over the next
several days.

     STL    COU     UIN
Fri10/28 85/1927 85/1927 85/1927



Saint Louis     51  61  52  81 /  20   0   0   0
Quincy          46  58  50  77 /  10   0   0   0
Columbia        48  64  52  80 /  10   0   0   0
Jefferson City  49  64  52  81 /  20   0   0   0
Salem           51  60  47  75 /  20   0   0   0
Farmington      54  63  49  76 /  30   0   0   0




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