Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 232045

Area Forecast Discussion
National Weather Service Saint Louis MO
345 PM CDT Sun Apr 23 2017

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 344 PM CDT Sun Apr 23 2017

Quiet and mostly clear sky on tap for tonight as sfc ridge very
slowly slides across the CWA tonight. As pressure gradient relaxes
this evening, expect winds to diminish and become light and
variable. The light winds, clear sky, and low dewpoints should yield
another seasonably cool night and went a degree or two below the
cooler MAV guidance for tonight...particularly in favored
terrain/valleys. This yielded lows ranging from the upper 30s to low
40s.  Similar to this morning, also cannot rule out at least
some patchy frost for these favored locations.

Winds will become predominantly southeasterly by midday on Monday as
sfc ridge slides eastward. Should be another mostly sunny sky with
quickly warming temperatures. Due to the expected plentiful
sunshine, rising heights, and warming low-level
temperatures...leaned warm for tomorrow`s highs compared to
guidance. Expect highs to range from the low to upper 70s.


.LONG TERM...  (Monday Night through Next Sunday)
Issued at 344 PM CDT Sun Apr 23 2017

Warmer and dry weather for Monday night and Tuesday, then the
pattern gets more active for much of the rest of the forecast
period.  Convection will spread southeastward into at least
northeast and central MO and west central IL Tuesday night as an
upper level trough and associated cold front approaches the forecast
area.  The models depict increasing upper level divergence over our
area ahead of the approaching upper level trough.  The cold front
will move southeastward through our forecast area on Wednesday as
the upper level trough deepens.  Following the slower solution of
the GFS and ECMWF models over the quicker NAM solution.  There may
be the potential of severe storms Wednesday afternoon across
southeast MO and southwest IL with strong deep layer shear due to a
strong mid level wind max ahead of the upper level trough.  The
amount of instability is in question depending on the morning cloud
cover and convection and the speed and position of the cold front
during maximum diurnal heating.  Should have a break in the
shower/thunderstorm activity late Wednesday night and Thursday with
cooler temperatures as cooler air filters into the region behind the
cold front.  Still some discrepency as to the start of the next
round of convection between the GFS and ECMWF model, but it appears
that precipitation should return to much of the forecast area on
Friday as we get into an active upper level southwest flow pattern
with a warm front shifting slowly northward through the region
leading to elevated convection Friday and Friday night.  May have
another break in the precipitation Saturday into Saturdy night, at
least across southeast MO and southwest IL as the warm front lifts
north of this area.  More convection, possibly severe will move
through our area Sunday ahead of a surface low and trailing cold



.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1246 PM CDT Sun Apr 23 2017

Clear sky with light northeast winds becoming light/variable
tonight before turning to the southeast Monday morning.


Clear/VFR through Monday afternoon. Northeast winds becoming
light/variable tonight, and then eventually southeasterly by late
Monday morning.





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