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000
FXUS63 KILX 081800
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1200 PM CST Sun Dec 8 2013

.DISCUSSION...
ISSUED 1022 AM CST Sun Dec 8 2013

Light snow associated with WAA/isentropic upglide is lifting
northward across the KILX CWA this morning. 16z/10am radar mosaic
and surface obs indicate that the steady snow has come to an end
along/south of a Jacksonville to Danville line. Further north,
snow will taper off to flurries in Bloomington within the next
hour, but will persist through much of the afternoon
along/northwest of the Illinois River in closer proximity to the
approaching upper wave. A light accumulation of up to 1 inch is
anticipated from the Peoria area northwestward. Elsewhere...only a
dusting to a couple tenths of an inch is expected. Forecast
soundings continue to suggest a loss of ice crystals within the
atmospheric column as drier air advects in aloft. Therefore any
light precip that occurs later this afternoon into the evening
will be in the form of freezing drizzle. Upstream obs still show
light snow/flurries in the St. Louis area: however, lower clouds
and a few freezing rain reports have been noted across
central/southern Missouri. Have updated the forecast to remove
snow mention across all but the far NW CWA from mid-afternoon
through the evening hours. Will have to carefully monitor the
trends/obs as an advisory for freezing drizzle may be needed later
today.


Barnes
&&

.AVIATION...
ISSUED 1159 AM CST Sun Dec 8 2013

MVFR ceilings will gradually lower to IFR this afternoon as the
atmosphere continues to slowly moisten from the top-down. Forecast
soundings suggest low ceilings and patchy freezing drizzle will
develop at the I-72 terminals by around 22z. Several hours of IFR
ceilings are anticipated, before westerly winds develop later this
evening and ceilings/visbys begin to improve from west to east after
the 03 to 05z time frame. Further northwest, light snow will
continue at KPIA for the balance of the afternoon before tapering
off and coming to an end by early evening. IFR ceilings should
remain east of the Illinois River, so will maintain MVFR
conditions at KPIA. MVFR ceilings return across the board after
midnight, as westerly winds bring drier air into the region.

Barnes
&&

.PREV DISCUSSION...
ISSUED 230 AM CST Sun Dec 8 2013

Initial wave of precipitation approaching the southern CWA early
this morning, with light snow being reported over parts of the St
Louis metro and as close as Litchfield at 230 am. Dry air initially
keeping the leading edge of the precip aloft, but the column will
be moistening quickly as isentropic lift persists. Initial
forecast concerns will be with precip through this evening
including specific type. Further out, focus remains on duration of
this cold snap.

SHORT TERM...Today through Tuesday:

Initial precipitation expected to be all snow this morning, then
concern shifts toward potential for some freezing drizzle as the
ice crystals in the column erode from the top down. Have kept
mention of freezing drizzle over most of the area this afternoon
except the far north, where the transition is more likely early in
the evening. Forecast soundings from the far southeast CWA
indicate some sleet potential as well. Not really looking for any
substantial ice accumulation aside from a minor glaze. Snow-wise,
could see around an inch near Galesburg and Peoria, with a half
inch elsewhere west of I-55 and a dusting to the east. Most of the
precipitation should be out of the area by mid evening.

Digging shortwave over Utah early this morning will begin to
accelerate eastward Monday, with associated jet streak passing
through southern Missouri/Illinois Monday night and Tuesday
morning. Evening model runs starting to come into more agreement
with a quick shot of light snow in a narrow band along this
streak. Have added some 30% PoP`s across areas south of I-70 late
Monday night as a result. Any accumulation looks to be just a
tenth or two at this point.

Temperatures will continue to remain well below normal. Winds stay
up enough that wind chills will be approaching 10 below near
Galesburg late Monday night and Tuesday morning, with sub-zero
readings elsewhere north of I-72.

LONG TERM...Wednesday through Saturday:

One last southward surge of cold air expected mid-week, before the
upper pattern finally starts to shift a bit. Unfortunately the GFS
and ECMWF showing some spread in how much this pattern shifts late
in the week, with the GFS in a much milder pattern across the
CONUS and the ECMWF keeping the path of cold air continuing
through the Great Lakes. Have kept with the trend of above-
freezing temperatures by Friday. After that, made no changes to
slight chance PoP`s Friday night/Saturday, as both models show
some sort of precip but do not agree on the frontal configuration.

Geelhart


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$