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000
FXUS63 KLSX 090027
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
627 PM CST Sun Dec 8 2013

.UPDATE:
Issued at 622 PM CST Sun Dec 8 2013

Made a quick update to issue a winter weather advisory this
evening for portions of eastern missouri and western illinois. A
band of a freezing drizzle/light snow mix extends from near KSPI
to KSTL to just east of KVIH. elsewhere there is patchy freezing
drizzle occurring. The combo will result in a thin glaze of ice on
untreated surfaces. Have already had a handfull of reports of
slick conditions. The precipitation should all be to the east by late
evening/midnight as flow becomes westerly and lower clouds exit.

Glass

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 258 PM CST Sun Dec 8 2013

Areas of sn and fzdz are quickly moving out of the CWA this
afternoon. Reduced visbys due to fg will linger across much of the
area into this evening, but are expected to improve as the cdfnt
pushes thru the area.

However, some very light fzdz may linger into the evening hours, but
is not expected to produce any ice accumulation. That said, with
temps dropping into the teens, refreezing will be an issue on roads.

With the weak sfc low moving thru the CWA tonight, have used a
non-diurnal temp trend overnight. Given temps behind this system,
have trended temps tonight twd the coolest guidance.

TILLY

.LONG TERM:  (Monday through Next Sunday)
Issued at 258 PM CST Sun Dec 8 2013

Model guidance continues to show an area of enhanced lift associated
with a shortwave rounding the base of the longwave trof Monday
night. In addition, the area will also be in the right entrance
region of a strong jet streak to the north and east. The result of
this forcing will likely be a narrow band of snow racing across the
southern part of the CWA dropping an inch or two of snow. Have not
increased PoPs to likely category as position of the band may still
change.

Rest of the work week should remain seasonally cold and dry. Have
trended cooler for temperatures in areas that have deep snow pack.
Coldest night appears to be Wednesday night/Thursday morning when
conditions will support good radiational cooling. Wouldn`t be
surprised if temperatures dip down toward zero over that snow cover
to the south of St. Louis.

Next shortwave moving out of the southwest CONUS will bring a threat
of precipitation to the region as early as Friday afternoon and
continuing into next weekend. Too early to pinpoint precipitation
types, but colder and less amplified ECWMF solution would suggest
widespread accumulating snow.

CVKING

&&

.AVIATION:  (For the 00z TAFs through 00z Monday Evening)
Issued at 542 PM CST Sun Dec 8 2013

Warm front has lifted north of forecast area. However, still have
an area of freezing drizzle with some light snow mixed in moving
east through the forecast area. Precipitation is expected to taper
off not too long after 00z Monday at taf sites, though ifr cigs and
vsbys to persist through the evening hours until a cold front
moves through during the overnight hours. The cold front will move
through KUIN by 04z, KCOU by 06z and metro area by 08z. The front
will bring in drier air allowing cigs to lift to mvfr, eventually
scattering out between 11z-14z Monday. As for winds, to persist
from the south this evening, then veer to the west to northwest
once the cold front moves through and remain between 5 and 10 kts.

Specifics for KSTL:
Warm front has lifted north of forecast area. However, still have
an area of freezing drizzle with some light snow mixed in moving
east through the forecast area. Precipitation is expected to taper
off not too long after 00z Monday in metro area, though ifr cigs and
vsbys to persist through the evening hours until a cold front
moves through by 08z Monday. The front will bring in drier air allowing
cigs to lift to mvfr, eventually scattering out by 14z Monday.
Will see cigs lower back down to low end vfr after 00z Tuesday as
an upper level shortwave approaches the region Monday night. As
for winds, to persist from the south this evening, then veer to
the west to northwest once the cold front moves through and remain
between 5 and 10 kts.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...WINTER WEATHER ADVISORY until Midnight CST tonight FOR Crawford
     MO-Franklin MO-Gasconade MO-Iron MO-Jefferson MO-Lincoln MO-
     Madison MO-Montgomery MO-Pike MO-Reynolds MO-St. Charles MO-
     St. Francois MO-St. Louis City MO-St. Louis MO-Ste.
     Genevieve MO-Warren MO-Washington MO.

IL...WINTER WEATHER ADVISORY until Midnight CST tonight FOR Adams IL-
     Bond IL-Brown IL-Calhoun IL-Clinton IL-Fayette IL-Greene IL-
     Jersey IL-Macoupin IL-Madison IL-Marion IL-Monroe IL-
     Montgomery IL-Pike IL-Randolph IL-St. Clair IL-Washington
     IL.

&&

$$

WFO LSX