Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 190827
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
327 AM CDT Fri Apr 19 2019

.SHORT TERM...  (Through Late Tonight)
Issued at 324 AM CDT Fri Apr 19 2019

Base of a slow moving 500 mb trough was moving south/southeast
across Missouri this morning.  On the forward side of this trough,
showers and low clouds were moving very slowly east/northeast.
These showers will linger over most of our far eastern Illinois
counties until a few hours after daybreak.

Quiet weather is expected over the next several days.  Clouds
associated with the aforementioned trough will gradually clear from
west to east, with some areas seeing the sun before sunset tonight.
Highs today will still be a little cool in the 50`s and lower 60`s
as cold advection dominates until the trough finally moves far
enough east of the Bi State area. Tonights lows will be colder than
Thursday night as cold advection and clear skies will allow for good
radiational cooling.  Temps will be around 40, with some upper 30`s
along and north of a Quincy, IL to Shelbyville, MO line.

Sally

.LONG TERM...  (Saturday through Thursday)
Issued at 324 AM CDT Fri Apr 19 2019


Saturday and Sunday will be progressively warmer and sunny each day
due to surface and 500mb ridging behind the departing low.  High
temps will climb into the mid to upper 60`s on Saturday and then
upper 70`s and low 80`s by Sunday.

The beginning of the workweek introduces another chance of rain and
thunderstorms, mostly in the far northern portion of the CWA.  A
stationary boundary sets up from northeast Illinois into the
panhandle of TX and moves ever so slowly south through Monday with
the eventual surface low moving northeast along the boundary.  This
will allow for a low chance of showers and thunderstorms, especially
in our northern CWA on Monday.

By Tuesday a deepening 500 mb low over the southwest CONUS will give
the midwest stationary front a kick which will push a cold front
through the Bi State region overnight Monday night and into Tuesday.
Moisture profiles aren`t great, but enough to keep a low chance POP
in for Tuesday.  The front stalls again on Tues night into
Wednesday, this time farther south, just south of the St. Louis
metro area and therefore chance POPS will continue into Wednesday.
With such variability in eventual placement of a stationary
boundary, timing and placement of precipitation chances will vary
for now.


Sally

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1147 PM CDT Thu Apr 18 2019

MVFR conditions, mainly due to lower ceilings, are co-located
with rain showers stretching from southeast Missouri into
southwest Illinois. A sharp cutoff exists from about KSTL westward
with scattered to broken mid-level ceilings over central
Missouri, giving way to clearing skies over western portions of
the state.

Mid and upper level moisture is expected to continue to decrease
from west to east through the morning and early afternoon. Rain
will push eastward and exit to the east as well. Expect VFR
conditions to take over through much of the Friday TAF period with
the main concern being related to gusty northerly winds. Gusts
could reach 25-30 knots in most locations through Friday
afternoon.

Expect VFR condition through the remainder of the period with
winds beginning to diminish around or just after sunset.

SPECIFICS FOR KSTL:

Rain continues to march southwest to northeast just east of
terminal. Briefs periods of rain have been observed over the last
couple of hours, but overall eastward progression should lower
rain chances through the early morning. Ceilings could slowly sink
into low VFR territory, before reaching down to MVFR before dawn
this morning.

While mid and upper moisture begins to diminish, plenty of low
level moisture will linger through the morning period. MVFR
ceilings persist from early this to potentially late morning and
early afternoon. Expect a gradual improvement as drier air finally
takes over and breaks ceilings from west to east.

Gusty northerly winds of 25-30 knots will become common through
the afternoon. This will diminish as deeper mixing is lost near
and after sunset Friday evening. Guidance still suggest the
potential for LLWS late Friday into early Saturday, which will
need to be monitored with later updates.

Maples

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



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