Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 271149

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
649 AM CDT WED JUL 27 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 312 AM CDT Wed Jul 27 2016

Despite some mid-high level cloudiness, fog has developed
overnight across portions of southeast MO and southwest IL due to
high surface dewpoints and calm winds. The fog was especially
dense in the FAM area. Scattered showers and thunderstorms are
expected to develop again later this morning and this afternoon,
mainly across southeast MO and southwest IL with the St. Louis
metro area on the northern fringe of most of the convection. This
activity will be associated with an old, weak frontal boundary
that has become stationary. High temperatures today will be
similar to yesterdays highs, and close to seasonal normals.


.LONG TERM...  (Tonight through Tuesday)
Issued at 312 AM CDT Wed Jul 27 2016

Relatively active pattern will continue for late July as
shortwaves carve out an upper level trough over the central US and
another weak, subtle cold front drops slowly southeastward through
our area Thursday and Thursday night. Will include chance pops
across most of the forecast area through the remainder of the work
week. The NAM model has a strong shortwave and associated surface
low moving eastward through MO and IL on Friday and Friday night.
It appears a little too strong with these features and prefer the
weaker solutions and lower QPF of the other models. The cloud
cover and precipitation should keep high temperatures to values
just below normal for Friday and Saturday. The chance of
convection should finally lessen, while the temperatures rise by the
start of the next work week as both the GFS and ECMWF models
depict a 595 decameter 500 mb high building over MO by Monday
night, along with mainly southerly or southwesterly surface winds.



.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 627 AM CDT Wed Jul 27 2016

SPECIFICS FOR KUIN: Isolated-scattered SHRA/TSRA will continue
today, but KUIN is too far north of the stalled front to be
affected by the rain before 28/00z. Fog is expected to develop
near the terminal after 28/06z.

SPECIFICS FOR KCOU: Fog developed overnight at KCOU, and
conditions should improve to VFR by mid-morning. KCOU is close
enough to a stalled front to be affected by isolated-scattered
SHRA/TSRA today. Fog is expected to develop once again overnight.

SPECIFICS FOR KSTL, KSUS, KCPS: Light fog was noted near the St.
Louis metro area terminals at TAF issuance, but conditions should
improve by mid-morning. The St. Louis metro area TAF sites are
close enough to a stalled cdfnt to be clipped by the continuously
percolating areas of SHRA/TSRA near the bdry, and this will
continue throughout most of the valid TAF pd. The 12z TAFs
attempt to highlight the two most likely pds for pcpn: this
morning (associated with ongoing sct SHRA/TSRA moving northeast)
and this aftn (new TSRA dvlpmt). Fog is expected once again





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