Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 250539
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1139 PM CST Wed Dec 24 2014

.UPDATE...
ISSUED AT 900 PM CST WED DEC 24 2014

Continued lift in the cyclonic flow will keep clouds and spotty
drizzle around the rest of the evening, and possibly a couple
hours after midnight. There could even be a few flurries later
tonight when air temps drop toward overnight lows around 32F. The
blanket of clouds may even keep lows temps up a couple degrees
above freezing in some locations. The clouds will likely stick
around until during the afternoon tomorrow, when the clearing line
should begin to advance across IL. Updated the weather to just
very light rain or patchy drizzle through midnight, and no mention
of snow or flurries later tonight. Low temps may be bumped up a
degree or two to account for thick layer of low clouds. Updated
info will be available shortly.

&&

.SHORT TERM...(Tonight)
ISSUED AT 310 PM CST WED DEC 24 2014

Weak system turned out a lot warmer and a little further to the east
with the heavier precipitation today.  Low clouds, rain and the
occasional mix with snow dominated Central Illinois today.  Showers
becoming far and few between as sunset approaches.  Pops are reduced
considerably as the system lifts out of the region. Expecting cloud
cover to remain in place with plenty of llvl moisture and clearing
not seen until west of the Missouri River valley on sat imagery.
Not dropping temps too far, though there is some concern as to
whether or not the lows will even drop that far into the 30s.
Precip ending before midnight as the system  pulls all precip  from
the state.

&&

.LONG TERM...(Thursday through Wednesday)
ISSUED AT 310 PM CST WED DEC 24 2014

High pressure will build into the region for Christmas Day bringing
dry conditions, but expecting clearing to struggle as an inversion
traps low level moisture. Temperatures will be mild reaching into
the 40s as breezy southerly winds develop due to a gradient between
the high centered to the southeast and approaching low pressure from
the west.

GFS, NAM, and ECMWF are in relative agreement with holding off
precipitation until at least Friday evening with the next low
pressure trough and cold front approaching from the west. This
should start out as rain, changing over to snow Saturday as the cold
front crosses the area. However, most precipitation should fall
before the change-over, so not expecting much if any accumulation.

Cooler highs in the 30s on Sunday across region behind the cold
front. Latest model runs keep a consensus for dry conditions under a
low-amplitude high pressure ridge until at least Tuesday morning,
then perhaps another weather system for midweek, however large model
inconsistencies develop by that time indicating large uncertainty.
What does appear more likely is a continued push of northwesterly
flow bringing much colder temperatures as the week wears on.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 1139 PM CST WED DEC 24 2014

The local radar images have shown a decrease in returns over the
last hour, so any lingering drizzle/flurries should be
diminishing. Will not include any mention of precip in the 06z
TAFS as anything additional overnight will have a negligible affect
on travel surfaces. Low cloud heights have oscillated in the last
few hours, with PIA jumping up to VFR and BMI and CMI dipping down
to IFR at times. Will go with prevailing MVFR cloud heights and
tempo in some IFR for BMI/CMI toward sunrise. Upstream obs in
Missouri show IFR clouds lingering under the sfc ridge axis, but
they may not advance over PIA and SPI by morning. After sunrise,
any IFR clouds should lift to MVFR, before some clearing develops
from west to east Christmas afternoon. Will continue with a
clearing trend, as the NAM/GFS/ECMWF all show a break up of clouds
during the afternoon. The NAM delays the clearing the most, which
seems more plausible based on the extent of clouds to the west.

Winds will be westerly through 12z then begin to shift to the SW
then S during Christmas Day. Wind speeds will remain brisk due to
a continued pressure gradient across IL, with sustained winds in
the 12-15kt range during the day and a few gusts around 20kt.

&&

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

$$

UPDATE...Shimon
SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Shimon






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