Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 191728

1228 PM CDT Sun Apr 19 2015

Issued at 1042 AM CDT Sun Apr 19 2015

Quick update to the forecast to try to capture precipitation and
temperature trends for late this morning and afternoon. Rain
showers continue to blossom across the CWA as low pressure moves
to the south of the region with coverage approaching 100 percent
from central Missouri to central Illinois. Temperature have
trended to fall a few degrees in moderate rain to wetbulb



.SHORT TERM:  (Through Late This Afternoon)
Issued at 405 AM CDT Sun Apr 19 2015

An area of showers and storms across southeast MO and southern IL
associated with a surface low near the MO bootheel will shift
northward through much of the forecast area this morning,
particularly the eastern half as the surface low moves northeastward
into southern IL by 18Z Sunday.  More scattered activity is expected
this afternoon as the upper level low over western KS opens up and
shifts eastward to near the KS MO border by 00Z Monday.  The models
depict upper level divergence over our forecast area ahead of the
upper level trough.  Some of the high resolution explicit models
depict a narrow line of convection shifting eastward through our
forecast area this afternoon.  With more cloud cover and
precipitation today the highs will not be quite as warm as
yesterday, but will still be slightly above normal.


.LONG TERM:  (Tonight through Saturday)
Issued at 443 AM CDT Sun Apr 19 2015

Showers and thunderstorms will continue tonight as the upper level
trough and associated cold front move eastward through our area.
The GFS model has a little higher pops and QPF over a portion of our
area tonight as it develops a surface low on the front which moves
northeastward through southeast MO and southern IL.  The other
models do not develop this surface low so am not real confident of
the GFS forecast solution and its higher pops and QPF.  Showers may
linger across IL Monday morning as more shortwaves move through the
area south of a northern Plains upper level trough.  Colder
temperatures can be expected tonight and Monday due to low level
cold air advection after the passage of the 850 mb trough and
surface cold front.  A persistent period of below normal
temperatures is expected for the upcoming work week due to the upper
level trough over the Great Lakes region and northwest flow over our
area.  More showers are expected Tuesday afternoon, mainly across
the southern half of our forecast area due to low-mid level warm air
advection ahead of a fast moving shortwave.  The chance of rain will
continue Tuesday night and Wednesday as a cold front drops southward
through our area.  This will bring a reinforcing shot of colder air
to the region Wednesday and Wednesday night with the models dropping
the zero degree C 850 mb isotherm southward to around STL.  Another
chance of rain is expected for Friday night and Saturday as an upper
level trough/low and associated surface low move eastward through
the region.



.AVIATION:  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1222 PM CDT Sun Apr 19 2015

Large area of rain showers continues to develop and slowly spin
northeast across the forecast area early this afternoon. Behind
this feature, isolated to scattered convection is developing where
heating has resutled from partial sunshine. Wind remains variable
as low pressure trof moves through the area.

For this afternoon, large area of rain will spin northeast into
Illinois with wind becoming predominately west in its wake. Will
see MVFR visibility in the moderate rain. Behind this rain
shield, scattered showers and thunderstorms are expected, but
coverage keeps a mention out of terminal forecasts for now. Cold
front will finally arrive later tonight with breezy conditions
expected Monday.

Specifics for KSTL:

Large rain shield will spin over the terminal the next few hours
providing MVFR visibility at times. Wind initially will be
variable as this trof of low pressure moves through, but will turn
out of the west by late afternoon. Scattered showers and
thunderstorms are expected to continue to develop on the fringe of
the main rain shield where breaks in the cloud cover has allowed
the local atmosphere to become unstable. Cold front arrives later
tonight with breezy northwest wind expected on Monday.





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