576 
FXUS63 KLSX 080341
AFDLSX

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
941 PM CST Wed Dec 7 2016

.UPDATE...
Issued at 928 PM CST Wed Dec 7 2016

Large and strong surface ridge building into MO from the northern
Plains tonight. Low-mid level cloudiness across southeast MO along
with flurries should shift south of the forecast area by midnight.
With a clearing sky along with continued low level cold air
advection and lowering surface dew points will lead to unseasonably
cold temperatures late tonight/Thursday morning. Lows tonight
will be close to 10 degrees below normal for early December. West-
northwest surface winds, gusty at times overnight will make it
feel colder.

GKS

&&

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 239 PM CST Wed Dec 7 2016

Area of light snow across parts of central MO is expected to
continue to sink south this afternoon and evening. Did pull PoPs and
mention of flurries a little further west with very dry boundary
layer in place. Still appears the accumulating snow will remain just
west of the CWA. 

PoPs drop quickly this evening as forcing pushes out of the region.
Expect clouds to clear out overnight. While the CWA should be
completely clear by sunrise Thurs morning, expect mixing to increase
overnight with gusts around 20 kts by 12z. Have overall trended twd
a compromise of guidance for temps tonight. 

As for temps on Thurs, while the area will remain under CAA with the
sfc ridge building into the region, a clear sky shud help push temps
upward with mixing as deep as 925 mb. However, given the cold air
under the ridge currently upstream, have still trended twd the
coolest guidance for Thurs. 

Tilly

.LONG TERM...  (Thursday Night through Next Wednesday)
Issued at 239 PM CST Wed Dec 7 2016

Main concerns during the long term are snow fall potential and
timing along with the cold weather. High pressure over the area will
slide into the Ohio valley by saturday morning. A progressive
shortwave will race over southern Iowa and into Indiana saturday
afternoon and evening. This will bring isolated chances of snow
showers to northeast Missouri into west central Illinois. 

Attention then turns to the cold front which will provide better
chance for snow fall to areas north of I-70 with a rain/snow mix
more likely for areas south of I-70 Sunday. It is too early at this
point to speculate on accumulation amounts.  All precipitation
should end west to east with frontal passage late sunday night into
early monday morning. An even colder shot of air comes in behind the
front Tuesday into Wednesday. 

Kelly

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 545 PM CST Wed Dec 7 2016

Any light snow or flurries should remain south of the taf sites
this evening. Band of mid level clouds should shift south of the
taf sites later tonight. Strong surface ridge over the northern
Plains will build southeastward into MO. West-northwest surface
wind will strengthen late tonight/early Thursday morning and
become gusty.

SPECIFICS FOR KSTL: Any light snow or flurries should remain south
of STL this evening. Band of mid level clouds should shift south
of STL late tonight. Strong surface ridge over the northern
Plains will build southeastward into MO. West-northwest surface
wind will strengthen late tonight/early Thursday morning and
become gusty. The surface wind will weaken Thursday night as the
surface pressure gradient relaxes.

GKS

&&

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

$$

WFO LSX