Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 270549
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1149 PM CST Fri Dec 26 2014

.UPDATE...
ISSUED AT 910 PM CST FRI DEC 26 2014

Weak low pressure is beginning to develop along the cold front,
over NE Missouri. Radar returns are confirming the increased lift
developing all around the low pressure from SE Missouri to S
Minnesota and S Wisconsin. Rain showers and areas of drizzle look
on track to overspread our forecast area from the southwest the
remainder of the night. Rainfall amounts should remain on the
lighter side, with most areas less than a tenth of an inch through
tomorrow. Temperatures will not drop far from current readings, as
cloud cover thickens and precip develops. Will keep low temps in
the low to mid 40s, which are well above normal highs for this
time of year. Southerly winds will continue in the 10-15mph range
through morning. Winds will shift to the SW as the low passes over
NW IL into Wisconsin early Saturday morning. West winds will
increase tomorrow in the wake of the low, as a cold front pushes
SE across our forecast area and cooler air flows into central IL.
Updated weather grids and forecast info will be available shortly.

&&

.SHORT TERM...(Tonight)
ISSUED AT 307 PM CST FRI DEC 26 2014

Deep trof over the western half of the CONUS this morning while weak
upper level ridging remains over the Atlantic seaboard.  Surface
high pressure sliding off to the east keeping southerly flow over
the region ahead of a slow moving cold front approaching the area
tonight. Temperatures well above normal today will give way to a
chance for precipitation tonight with the passage of the front.
Forecast soundings remain rather shallow with the saturation and
looks to be more drizzle and low clouds...maybe some light rain.
Not a lot of QPF expected.  Guidance shows some patchy light winds,
and close to the low center with a weaker wind gradient associated
with the immediate front...may see a little bit of mist/fog, but
should be more of a low cloud, drizzle situation.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 307 PM CST FRI DEC 26 2014

Cold front to push from near Galesburg around 6 a.m. southeastward
to around Lawrenceville by 6 p.m. Rain showers or drizzle with
this frontal boundary could turn over to snow just before ending,
however it looks as if the bulk of precipitation will fall as rain
so still expecting no snow accumulation. Precipitation amounts
should also be quite light as upper level dynamic lift bypasses
central IL to the northwest. Model precipitation fields are
consistent with this idea. The front should stall out just
southeast of Lawrenceville Saturday night as another upper level
wave approaches from the west. This will cause the front to move
again, with precipitation intensifying just southeast of
Lawrenceville. Temperatures will fall behind the front, with
temperatures peaking before noon from around I-55 westward.

Temperatures near normal with dry conditions Sunday and Monday, as
arctic high pressure settles into the Plains. By midweek, a series
of upper level troughs digging into the Midwest will push more cold
air into the region, with highs only reaching the low to mid 20s and
lows in the teens or potentially colder. Expecting this period to
remain dry. The next good chance for precipitation will be at the
end of next work week as a strong trough could potentially eject out
of the Southwest across the southern Plains.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1149 PM CST FRI DEC 26 2014

Low pressure has moved NE along the cold front this evening,
reaching just west of Macomb at 0530z. Clouds are still at VFR
levels for another hour or two across our forecast area. The low
pressure will continue to advance NE up the front, passing over
Lake Michigan by Saturday morning. As the low departs, a cold
front extending south of the low will advance across our forecast
area. Upstream observations and forecast soundings point toward MVFR
clouds progressing over the terminal sites after midnight, with IFR
clouds accompanying the low as it moves over NW IL between 07z
and 12z. An initial push of rain will mainly affect the eastern
terminals of SPI/DEC/CMI/BMI through 09z. Additional rains are
expected to develop behind the initial line of showers, helping
drop cloud heights to IFR for several hours around sunrise.
Precipitation should diminish by Saturday afternoon, as the cold
front advances SE across the area and dry air aloft begins to
invade.

Winds will remain steady from the south at 9-14kt the rest of
tonight. The KILX VAD wind profiler shows that the low level jet
has already developed in central IL, with 35-40kt of winds at 2k
FT. Therefore we continued to include LLWS conditions for the
first 4-5 hours of this TAF period. Winds may back to the
southeast in the vicinity of the low toward PIA later tonight, but
then shift around to the SW then W during the day on Saturday
behind the cold front. Colder air will arrive on the increasing
W winds, with speeds of 13-16kt expected during the afternoon.
Winds will eventually veer to the NW Sat evening, as they diminish
below 10kt.

&&

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

$$

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





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