Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 130427
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1127 PM CDT Fri Sep 12 2014

.UPDATE:
Issued at 1027 PM CDT Fri Sep 12 2014
Issued at 620 PM CDT Fri Sep 12 2014

cloud cover continues to slowly recede southeastward across north-
central Missouri. Light to moderate drizzle still continues over
much of central Missouri into southwest and central Illinois.
Light to moderate drizzle will continue over parts of central and
much of east-central - southwest illinois through early Saturday
morning. Cloud cover will slowly recede southward with time. But
will still continue to linger beyond 0900 UTC. Surface winds will
be dimishing to 5 kts after 0600 UTC. temperatures will drop intot
he upper 30s over far northeast Missouri tonight under clear
skies. Should be a fine day on Saturday with partly cloudy skies
and mild tempatures over the region as surface high pressure
builds over the area. Could reach record lows for far northeast
Missouri and again on Sunday morning for northeast through central
Missouri.

Przybylinski

&&

.SHORT TERM:  (Through Tonight)
Issued at 236 PM CDT Fri Sep 12 2014

Cloud cover continues to cover the area this afternoon as stratus is
trapped under a low level inversion and mid-high level clouds are
streaming in ahead of a mid level trough.  There has been some light
rain associated with the mid-level trough moving across northern
Missouri early this afternoon, but it`s coverage has been limited.
Latest runs of the RAP and HRRR still show some redevelopment of
some light rain over western Missouri this afternoon and this
evening ahead of the upper trough that will move across the CWA this
evening.  Then expect clearing of the clouds from north to south
after 06Z as the upper trough moves to the east allowing subsidence
to set in.  Drier air will move into the low levels as the inversion
weakens which should allow the low level clouds to move out.
Temperatures should fall close to agreeable MOS guidance for lows
once skies begin to clear with the light northeasterly winds.

Britt

.LONG TERM: (Saturday through Next Friday)
Issued at 236 PM CDT Fri Sep 12 2014

(Saturday through Monday)

Overall, mdls are in good agreement thru this period. Period begins
with a large sfc ridge settling across the region. This ridge will
keep temps around 15 degrees below seasonal average despite ample
insolation. As the ridge retreats, the approaching trof and sfc fnt
will bring another chance for precip to the region late in the
period. Some minor differences in timing are apparent among the mdl
guidance. Will keep PoPs lower except where mdls are in agreement.

(Tuesday through Friday)

Not much change from the prev forecast. Mdls remain in good
agreement overall thru the period with respect to mass fields
anyway. Sfc ridge builds into the region on Tues with precip coming
to an end Mon night. Cool temps will prevail thru mid week, tho not
as cool as this weekend. Mdls differ regarding precip chances for
late Wed into Thurs. The ECMWF is more robust with nocturnal
convection developing along a stationary fnt across the region. The
GFS would suggest height rising with the sfc ridge still holding on
into the area. Have kept PoPs low given the uncertainty forecasting
mesoscale features on day 7.

As for temps, have trended twd the warmer guidance thru the period
given heights over the region.

Tilly

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1119 PM CDT Fri Sep 12 2014

Subsidence and dry air advection at low levels are significantly
eroding the MVFR stratus in place across the region. The clearing
line has already moved through KUIN and KCOU and should reach St.
Louis metro TAF sites during 06-09z. There could be some isolated
spots of fog once clearing occurs, but the combination of drying
low levels and sustained winds AOA 7kts should act to limit any
fog formation to those sheltered areas with higher low-level
moisture. Generally VFR conditions are expected thereafter.

Kanofsky

&&

.CLIMATE:
Issued at 236 PM CDT Fri Sep 12 2014

Record Lows This Weekend:

       STL        COU        UIN
13   43(1975)   33(1902)   33(1902)
14   46(1996)   40(1892)   38(1996)


&&

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

$$

WFO LSX






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