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000
FXUS63 KILX 101747
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1147 AM CST Tue Dec 10 2013

.DISCUSSION...
ISSUED 1039 AM CST Tue Dec 10 2013

Morning surface analysis shows low pressure over northern
Wisconsin, with cold front trailing southwestward into Iowa.
Ahead of the front, W/SW winds have brought slightly warmer air
into central Illinois. After overnight lows in the single digits
below zero in some areas, 16z/10am temps have rebounded into the
lower 20s. The exception is across the far southeast where a
substantial snow cover exists and current readings are hovering in
the teens at both Olney and Lawrenceville. Cold front will swing
through the region this afternoon, but not before high temps reach
the middle to upper 20s. Have made adjustments to hourly
temps/dewpoints and nudged highs up a degree or two accordingly.
Changes are minor and do not require a zone update at this time.


Barnes
&&

.AVIATION...
ISSUED 1147 AM CST Tue Dec 10 2013

Strong westerly winds gusting to between 20 and 25kt will persist
through the afternoon before gradually subsiding and backing to
southwesterly toward sunset. Light southwesterly winds will
continue through the night then will veer back to the northwest
and gust to around 20kt behind a departing storm system Wednesday
morning. Skies will initially be clear this afternoon, then
mid-level clouds will increase this evening in advance of a
fast-moving clipper system expected to track across north-central
Illinois overnight. The best moisture and strongest lift
associated with this system will remain north of the central
Illinois terminals, but may graze KPIA late tonight into Wednesday
morning. Have therefore included a period of light snow and MVFR
ceilings between 09z and 14z at KPIA. Once the wave passes and
winds become northwesterly, forecast soundings suggest MVFR
ceilings of around 2500ft will spread across the entire area after
14z.

Barnes
&&

.PREV DISCUSSION...
ISSUED 247 AM CST Tue Dec 10 2013

Fast moving area of light snow, along axis of 170+ knot jet at 300
mb, is slowly shifting southward but is persisting in the extreme
southeast corner of the forecast area. An area of clearing has
pushed through a good portion of the CWA northwest of I-70, and
temperatures have been dipping below zero northwest of the
Illinois River. Clouds are already quickly moving east through
Iowa, associated with the next shortwave that is currently diving
southeast through Minnesota.

Several waves/storm systems to focus on over the next several
days, with the Friday night system of most concern for widespread
wintry weather over the forecast area.

SHORT TERM...Today through Thursday:

Incoming wave this morning will only provide us with a glancing
blow of the mid/high clouds, however rather blustery conditions
can be expected. Next wave of concern is currently dropping into
western Montana, with and will rapidly track southeast. Latest
models continue to produce light snow from northern Iowa into
northern Illinois overnight, exiting the area Wednesday morning.
Main snow axis expected to be just north of us toward the I-80
corridor, but a half to 1 inch of snow is plausible across the
extreme northern CWA from Galesburg to Minonk. Temperatures only
expected to reach the mid to upper 20s today, but hold fairly
steady in the teens overnight.

Next surge of Arctic air poised to drop southward through the
Great Lakes on Wednesday, as the snow exits. Will go with falling
temperatures over most of the CWA Wednesday afternoon. Lows
expected to drop into the zero to 5 above range Wednesday night,
with wind chills below zero in most areas. This shot of cold air
will be brief though, with some slow moderation beginning on
Thursday.

LONG TERM...Friday through Monday:

Forecast starts to become more complicated toward the end of the
week, as the split upper flow tries to phase a bit and develops a
significant trough across the middle of the country. Longer range
models coming into better agreement with timing of precipitation
and surface features that will affect our area later Friday into
early Saturday, but are still struggling a bit with the precip
type. Some indications of a bit of sleet or rain possible Friday
afternoon, primarily across the southeast, before changing back
over to snow. Currently looking like a couple inches of snow will
be possible, especially southeast of I-55 where heavier precip
will track northeast ahead of the main wave. Snow will taper from
west to east on Saturday.

Later in the weekend, the models are in reasonable agreement with
dropping a closed low into the upper Great Lakes region, with an
associated surge of Arctic air. However, they have a rather wide
spread on exactly how intense and far south this air mass will
reach, with 850 mb temperatures over us ranging from -3C on the
ECMWF model, to -18C on the GFS and -28C with the Canadian model.
The latter model would suggest highs well below zero. Temperature
grids will trend more toward the ECMWF, suggesting mainly 20s over
the area.

Geelhart


&&

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

$$