Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 281949

Area Forecast Discussion
National Weather Service Lincoln IL
249 PM CDT FRI OCT 28 2016

.SHORT TERM...(This evening through Saturday)
ISSUED AT 249 PM CDT Fri Oct 28 2016

Warm and windy for tonight and into tomorrow morning as the Midwest
is between an exiting high pressure, and a developing storm system
well to the northwest.  The increasing gradient and winds just off
the surface to 40 kts later tonight...will result in gusts this
afternoon and evening with some turbulent mixing, and potentially
into the overnight. The gusts may calm a bit after midnight...but
the winds will still stay up in the 10-15kt range out of the SSW.
The intense southerly flow will keep the overnight lows up a bit,
mainly in the upper 50s/lower 60s...which is 15-20 degrees F over
last nights lows. Tomorrow the winds veer to more southwesterly
flow...continuing to advect plenty of warm air into the region and
highs tomorrow will soar into the upper 70s/lower 80s.


.LONG TERM...(Saturday night through Friday)
ISSUED AT 249 PM CDT Fri Oct 28 2016

Above normal temperatures will highlight the extended forecast, as
relatively zonal flow in the upper levels prevents any deep pushes
of cold air into Illinois.

Saturday night will see low pressure advancing across Illinois which
will help pull a cold front south into central Illinois. The better
forcing for precip will remain north of the low across northern IL,
therefore only expecting spotty showers north of a line from Canton
to Champaign after midnight Saturday night through sunrise Sunday.
Low temps Saturday night will remain quite mild, with readings
ranging from around 55 near Galesburg to around 60 south of Lincoln.
The cold frontal passage Sat night will keep Sunday a little cooler
than Saturday, but highs should remain above normal ranging from the
low 60s north of I-74 to the mid to upper 70s south of I-70.

The cooler temps will be short-lived, as southerly warm air
advection flows crank up by sunrise on Monday. 850mb temps are
projected to climb into the 17 to 19C range by 00z/7pm Monday. Gusty
southwest winds mixing those temps to the surface would support high
temps in the low 70s N of I-74 and the upper 70s S of Springfield to
Mattoon. Very similar temperatures will linger into Tuesday as a
cold front approaches western Illinois, and central Illinois remains
in the warm sector of the nearby frontal system.

There are model differences in how that front progresses on Tuesday
night and Wednesday. Overall consensus is that low pressure will
drift toward or into NW Illinois, lifting the front northward as a
warm front on Wednesday. That would provide yet another day of very
mild temperatures in the 70s, but would also bring increasing clouds
and chances of rain. We have slight /20%/ chances W of I-55 after
midnight Tues night and Wed morning, with chance /30-40%/ PoPs Wed
afternoon NW of the IL river. Rain chances climb to high chance and
low likely /50-60%/ Wed night through Thursday morning as the front
is pulled across Illinois by low pressure departing into the Great
Lakes. Instability looks weak in general, but isolated thunderstorms
could develop during that time, with help from marginal bulk wind

Model differences become more pronounced for Thurs night and Friday,
as the ECMWF slowly pushes low pressure across Illinois in contrast
to the GFS solution of advancing the cold front southeast of
Illinois under advancing high pressure. For this update, the
extended blend leaned toward the dry GFS, which seems more
reasonable in the zonal flow pattern.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1257 PM CDT Fri Oct 28 2016

Mainly a cirrus forecast with southerly winds moving in on the
back side of a ridge axis throughout the TAF pd. However, it bears
mentioning that not only will the gusts stay up a bit through the
evening hours tonight...but it will be borderline LLWS criteria
with winds btwn 1500-2000 ft being up to near 40


.ILX Watches/Warnings/Advisories...


LONG TERM...Shimon
AVIATION...HJS is the U.S. government's official web portal to all federal, state and local government web resources and services.