363 
FXUS63 KLSX 101208
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
708 AM CDT Wed Oct 10 2018

.SHORT TERM...  (Through Late Tonight)
Issued at 310 AM CDT Wed Oct 10 2018

Cold front extending from a surface low over west central IA 
south through northwest MO and southeast KS will move eastward 
today as a negatively tilted shortwave moves the region. A north 
to south band of showers and a few embedded thunderstorms was 
moving into the St Louis metro area early this morning, and will 
continue to translate slowly eastward. This activity was ahead of 
the cold front and in a region of low level moisture convergence 
associated with a southerly low level jet. There will be the 
potential for isolated strong to severe thunderstorms containing 
locally heavy rainfall and damaging winds today, mainly across 
southwest IL due to favorable low-mid level wind shear as a mid 
level wind max moves over the area, along with sufficient CAPE. By
afternoon most of the showers and storms will be across southwest
IL into parts of southeast MO. Temperatures will fall today due 
to strong low level cold air advection behind the cold front. 
Tonights lows will be much colder as a large and strong surface 
ridge over the northern Plains builds southeastward into MO, 
ending the chance for rain by early evening. Lows tonight will 
only be 5 to 10 degrees below normal, but it will feel quite cold 
due to the unseasonably warm conditions experienced for much of 
October so far.

GKS

.LONG TERM...  (Thursday through Tuesday)
Issued at 310 AM CDT Wed Oct 10 2018

Dry and much colder conditions can be expected Thursday and 
Thursday night. It may be cold enough across northeast MO and west
central IL for patchy frost late Thursday night and early Friday 
morning, although increasing cloudiness will hinder frost 
formation. The models are now stronger with an upper level trough 
moving eastward through our region on Friday and hence have more 
QPF for the forecast area Friday into Friday evening despite the 
relatively dry surface/boundary layer with the surface ridge over 
our area on Friday. With cloud cover hindering diurnal solar 
insolation on Friday high temperatures should be 15 to 20 degrees 
below normal. Will see slightly warmer temperatures on Saturday 
with surface winds becoming southerly on the backside of the 
retreating surface high. Another round of precipitation can be 
expected Saturday night and Sunday, and possibly lingering into 
Monday morning. A southern stream shortwave and associated surface
low will pass south of our area and lead to showers, particularly
across southeast MO and southwest IL. A northern stream shortwave
and associated cold front will drop southeastward through our 
forecast area Sunday and Sunday night behind the surface low. The 
operational GFS is a little more progressive than the ECMWF model 
and shifts the precipitation southeast of our forecast area Sunday
afternoon, while the ECMWF does not shift the rain southeast of 
our area until Monday afternoon. For now will lean toward the 
slower solution. The cold front will bring another shot of cold 
air into the region Sunday night and Monday. Both the GFS and 
ECMWF bring the zero degree C 850 mb isotherm south of our 
forecast area on Monday.

GKS

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 656 AM CDT Wed Oct 10 2018

Showers and scattered thunderstorms will affected KUIN and the St.
Louis area terminals this morning. There will also be a chance of
storms in the St. Louis area terminals this afternoon before a
cold front moves across the area. There will be MVFR and some IFR
ceilings and visibilities today before they clear out behind the
cold front. Winds will gust up to 20 knots today before decreasing
tonight.

SPECIFICS FOR KSTL: 

Showers and scattered thunderstorms will move through the area
this morning into early this afternoon. There will be MVFR and 
some IFR ceilings and visibilities today before they clear out 
behind the cold front. Winds will gust up to 20 knots today before
decreasing tonight.

Britt

&&

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

$$

WFO LSX