Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 282003
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
303 PM CDT Sun Sep 28 2014

.SHORT TERM...(Tonight)
ISSUED AT 302 PM CDT SUN SEP 28 2014

The 581 dm 500mb low over central Iowa will become an open wave and
drift southeast across MO and sw IL tonight. That will just bring
scattered cirrus clouds with it to central IL, while diurnally driven
few to scattered cumulus clouds 5-7k ft dissipate around sunset. A
shallow layer of moisture below a subsidence inversion will allow
some patchy ground fog to develop again near river valleys like the
IL and Wabash rivers overnight. Any fog that develops overnight
should dissipate by 830 am Monday morning. Lows overnight will be
similar to last night lows and current dewpoints in the low to mid
50s with coolest readings over east central IL. Winds will remain
light to calm through Monday morning under a weak surface pressure
gradient as 1021 mb high pressure and ridging into WI, northern IL
and eastern IA remains in place through Monday.

&&

.LONG TERM...(Monday through Sunday)
ISSUED AT 302 PM CDT SUN SEP 28 2014

Quiet weather is still expected for the start of the work week.
Shortwave currently entering western Saskatchewan will be digging as
it approaches Lake Superior, forming a closed low over Lake Huron by
early Tuesday. This will push a cold front southward, with all
models indicating it getting into central IL before lifting back
north as a warm front on Wednesday.

Then a broad trough in the Rockies will slowly move east into the
plains. The first surface low associated with this feature will lift
northeast into the northern plains with showers and thunderstorms
trailing just ahead of a front in the plains, slowly moving east.
This first batch of pcpn will not make it into the CWA, as it will
be well away from it`s best support and it will be moving into a
strong ridge. The cold front will still be west of the area, but
will refire with showers and thunderstorms Wed night. The front will
also be moving into the area Wed night and Thur, so pcpn will become
likely through Thur night, across the CWA. A strong surge of cooler
air move into the midwest on Friday behind the front. Models differ
on timing of all this pcpn and believe the ECMWF/GEM have the best
handle on the timing of onset of the pcpn, while the GFS is too
fast. Beyond this system and into the weekend, much cooler high
pressure will build into the area for the weekend.

850 mb temperatures in the 13-15C range will keep our highs above
normal, with some cooling on Tuesday as the front moves south into
the CWA and then back north Tue night. Temps will stay above normal
for Thur ahead of the cold front and pcpn, but then cool behind this
front for the remainder of the week and into the weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 1245 PM CDT SUN SEP 28 2014

Used persistance for the central IL aviation forecast next 24 hours
through 18Z/Mon. Few to scattered cumulus clouds 5-7k ft this
afternoon especially from I-55 west, will dissipate by sunset at
2345Z. Otherwise patches of high clouds to occur next 24 hours
while few-scattered cumulus clouds reappear after 16Z Mon especially
from I-55 west again. Light and variable winds to prevail through
early Mon morning and then have nnw winds 3-5 kts after 16Z Monday.
1022 mb high pressure over lower MI and ridging westward into WI,
northern IL and eastern IA to remain near central IL through
Monday. This to continue fair weather through Monday as upper
level ridge extends from Texas up to IL. Patchy shallow ground fog
possible from 09-13Z along IL river at PIA where vsbys could lower
to MVFR of 5 miles.

&&

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

$$

SHORT TERM...07
LONG TERM...Auten
AVIATION...07





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