Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 212045
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
345 PM CDT SUN AUG 21 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 344 PM CDT Sun Aug 21 2016

Very quiet as SFC ridge retreats with the ridge axis drifting east
of the CWA overnight. Shortly after sunset the diurnal cu will dsspt
and winds will become lght/vrb. This is ideal radiational cooling
which should translate to widespread low temps in the 50s with just
the heart of metro area remaining in the low 60s. Winds will
eventually become S/SE by Mon mrng.

2%

.LONG TERM...  (Monday through Next Sunday)
Issued at 344 PM CDT Sun Aug 21 2016

The quiet weather pattern will continue on Monday with subtle upper
level ridging over the area along with a strong surface ridge
extending from the Ohio Valley region southwest through southeastern
MO.  A slow warming trend will begin as the surface/low level winds
become southerly as the surface/850 mb ridge begins to shift east of
the area.  The chance of showers/storms will return on Tuesday west
of the Mississippi River as the surface/low levels begin to moisten
with rising humidities.  Low-mid level warm air advection can also
be expected with weak southwest flow shortwaves beginning to impact
the region.  Nocturnal convection is possible Tuesday night with the
models depicting a southwesterly low level jet across northern MO.
The best chance of rain will be across northeast and central MO and
west central IL.  The chance of showers and storms will continue
Wednesday and Wednesday night as an upper level trough moves
eastward through the northern Plains and sends a cold front
southeastward into our forecast area.  This front will be slow
moving with an upper level ridge over the southeastern portion of
the US.  This front should make it into southeast MO and southwest
IL on Thursday with continued convection along it.  There may be a
break in the rain chances Thursday night and Friday across most of
the forecast area with a surface ridge moving through the region,
but then return Friday night or Saturday as the surface ridge shifts
east of the area with southerly, moist low level flow returning. The
GFS model is a little more aggressive in bringing convection back
into our area than the ECMWF model.  The ECMWF model is a little
slower in shifting the surface ridge east of the region.

GKS

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1247 PM CDT Sun Aug 21 2016

VFR fcst thru the prd. SFC ridge in control today with ridge axis
sliding east of the area tonight allowing winds to go lght/vrb
overnight...then S/SE by Mon mrng. Expect diurnal cu once again
tomorrow.

SPECIFICS FOR KSTL:

VFR fcst thru the prd with winds aob 10kts. SFC ridge moves east
of the terminal tonight allowing winds to become S/SE by Mon
mrng.

2%

&&

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

$$

WFO LSX



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