Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 170931

431 AM CDT Fri Oct 17 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 319 AM CDT Fri Oct 17 2014

A cold front extending from a surface low over WI southwest through
east central MO will continue moving southeastward through the rest
of our forecast area this morning as an upper level low over
northeast MN moves southeastward through the Great Lakes region
today.  Precipitation is not expected across our forecast area today
in association with this front, but cold air advection behind this
front will lead to cooler high temperatures for northeast and
central MO as well as west central IL today compared to yesterdays
maximum temperatures.  There was also a large area of low level
clouds across the northern Plains which will advect southeastward
into northeast MO later this morning and into west central IL and
parts of central MO this afternoon.  This cloudiness will limit
solar insolation this afternoon and hinder the diurnal rise in
temperatures along with the post frontal low level cold air


.LONG TERM:  (Tonight through Thursday)
Issued at 431 AM CDT Fri Oct 17 2014

Cooler low temperatures are expected tonight due to the upper level
trough over the Great Lakes region and low level cold air advection
across the entire area as a relatively strong and large surface
ridge over the northern Plains builds southeastward into MO.  The
models drop the 4 degree C 850 mb isotherm southward to just south
of STL by 12z Saturday.  The models bring a strong shortwave
southeastward through IL on Saturday.  Any precipitation associated
with this feature should remain east of our forecast area, but this
shortwave may bring a reinforcing shot of cold air to the region.
The coldest temperatures should occur Saturday night due to good
radiational cooling as the surface ridge axis moves through our
forecast area with a mostly clear sky along with light surface winds
and surface dew points dropping into the middle 30s to around 40.
There may be light patchy frost in the colder, low lying locations
late Saturday night.  Are only chance of rain this forecast period
will occur Sunday night and Monday as a northwest flow shortwave and
associated cold front drop southeastward through the region.  The
models do depict a narrow band of low-mid level warm air advection
and moisture ahead of this shortwave and cold front.  The NAM model
does not generate any precipitation across our forecast area, while
the ECMWF model keeps most of the precipitation just east of the
forecast area.  The GFS model does have some light QPF mainly across
east central and southeast MO as well as southwest IL late Sunday
night and Monday.  For now will just include slight chance pops
across parts of the forecast area late Sunday night and Monday.
Cooler temperatures are expected for Monday night and Tuesday,
particularly across IL with a deep upper level trough over the Great
Lakes and Ohio Valley regions.  Dry conditions for the remainder of
the extended forecast with surface ridging across our area, and as
an upper level ridge moves slowly eastward into MO.



.AVIATION:  (For the 06z TAFs through 06z Friday Night)
Issued at 1109 PM CDT Thu Oct 16 2014

Dry and VFR conditions are expected through the TAF period.
Southerly winds are expected to turn westerly behind a cold front
that will move across the area between 06-08Z. Wind speeds and
gusts will increase after 15Z tomorrow with VFR deck of clouds
building south across the Midwest.

Specifics for KSTL:
Dry and VFR conditions are expected during the next 30 hours with
a cold FROPA around 07Z. Wind speeds and gusts will increase
after 15Z tomorrow with VFR cloud deck advancing overhead by 01Z.





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