Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 301736
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1136 AM CST Fri Jan 30 2015

.UPDATE...
ISSUED AT 1135 AM CST FRI JAN 30 2015

After coordination with WPC and surrounding offices, a winter
storm watch is being issued for a large part of our forecast area,
except along and south of I-70. Forecast soundings from the
southeast CWA indicate a fair amount of mixed precip or even rain
on Sunday, lowering the threat of significant snowfall in that
area. Further north, heavier amounts of 6-8 inches are indicated
north of a Havana to Paris line, with the heaviest snow axis
expected to set up a little further north in east central
Illinois. Updated products will be out shortly.


UPDATE ISSUED AT 945 AM CST FRI JAN 30 2015

Little change needed to the morning forecast, but did update high
temperatures a degree or two in some areas. Band of altocumulus
in the upper Mississippi Valley is tracking southeast, but the
trajectory would favor the thicker clouds staying just to our
northeast. Some increase in cirrus expected from the west as well,
but skies generally to remain mostly sunny as ridge axis moves on
top of us.

Early look at the 12Z NAM for this weekend continues to favor the
northern half of the forecast area for the heavier snow amounts,
with the GFS just starting to arrive. Will be coordinating with
WPC and neighboring offices on any headlines, which may be issued
before the regular afternoon forecast package.

&&

.SHORT TERM...(Today)
ISSUED AT 329 AM CST FRI JAN 30 2015

High pressure will build across central and southeast Illinois today
from the northwest. This Canadian high will bring cooler air into
the area than yesterday, but the fact that winds will be much
lighter and at least partly sunny skies are anticipated should make
for a decent late January day. The only real wild card today from
what should be a quiet weather day is how much cloud cover there
will be. Skies across the area are rapidly clearing from the
northwest as the high builds in, but there are still significant
patches of clouds upstream beneath the ridge axis across the upper
Midwest. For now, plan to be optimistic with cloud cover given the
clearing that has taken place so far, and the fact that forecast
soundings do not suggest significant low level moisture trapped
beneath the subsidence inversion.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 329 AM CST FRI JAN 30 2015

00Z Jan 30th forecast model suite continues to trend further north
with ECMWF model the further north and much further north than its
model runs a few runs ago. Consensus of models has heaviest snow
band to set up over our northern counties north of a Springfield to
Paris line during Saturday night and Sunday where 6-8 inches of snow
and locally higher amounts possible. Between 3-5 inches of snow
south of I-70 in southeast IL where mix precipitation to occur Sat
afternoon/evening before changing to all snow by overnight Sat night
into Sunday. Will issue another SPS to address the potential of several
inches of snow accumulations Saturday night and Sunday especially
from I-72 north. A winter storm watch may eventually be needed
Saturday night and Sunday especially over northern counties.

1037 MB high pressure over MN into the central plains will drift
east into the Ohio river valley by midnight tonight and into the mid
Atlantic States Sat morning and continue dry weather over central
and eastern IL. Lows tonight mostly in the lower 20s with a few
upper teens from Champaign and Paris northeast.

Low pressure organizing in the SW states to deepen surface low
pressure NE into the central Ohio river valley by sunset Sunday.
This to spread mixed precipitation into central IL during Sat
afternoon with areas from Lincoln south mainly light rain and mix of
light rain/snow northern counties with little or no snow
accumulations during daytime hours Sat. Highs Sat in the lower 40s,
with upper 30s from I-74 north. Brunt of snow and moderate at times
to develop during Saturday night into Sunday with mix of rain/snow
SW counties Sat evening. Models have trended heavier with QPF close
to three quarter inches and snowfall amounts especially north of
I-70. NE winds to veer north and increase during day Sunday from NW
to SE and temperatures will likely be slipping Sunday especially in
afternoon with some blowing snow developing by Sunday afternoon into
Sunday evening. Light snow to diminish from the west during Sunday
night as low pressure pulls away from IL.

Canadian high pressure drifts down into IL from western Canadian Rockies
by Monday afternoon returning dry but cold weather as skies become
partly to mostly sunny. Highs Monday only in upper teens and lower
20s Monday due to expected snow pack. Temps briefly climb Tue into
low to mid 30s with breezy SSW winds ahead of clipper system that
moves into Great Lakes region Tue night and swings a cold front SE
through IL Wed bringing chances of light snow and flurries. Even
colder air to follow this weather system for from Wed night through
Friday with lows possibly getting below zero Thu night after highs
Thu in mid to upper teens over central IL with lower 20s south of
I-70.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1135 AM CST FRI JAN 30 2015

VFR conditions to remain on tap through the forecast period. We
are seeing some stratocumulus developing over the eastern half of
Illinois around 2000 feet, but this should remain scattered for
the most part. General trend will be for high clouds to spread in
from the west later tonight and especially on Saturday. Northeast
winds have started to become light and variable as an axis of high
pressure moves overhead, but will trend more south/southwest this
evening as the axis moves to the east.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from Saturday evening through Sunday
afternoon FOR ILZ027>031-036>038-040>057.

&&

$$

UPDATE...Geelhart
SHORT TERM...Bak
LONG TERM...07
AVIATION...Geelhart





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