Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 301145
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
645 AM CDT SAT JUL 30 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 332 AM CDT Sat Jul 30 2016

Short-wave trough evident on 08z/3am water vapor imagery over
northern Illinois will be the primary weather-maker across the
region today.  Numerous slow-moving thunderstorms developed in
advance of this feature across eastern Iowa/northern Illinois
yesterday afternoon, with this convection producing outflow
boundaries that settled southward toward the I-74 corridor during
the evening.  While the strongest synoptic lift associated with the
upper wave will be a bit further east across Michigan/northern
Indiana today, think it will still be close enough to provide
enhanced lift along the lingering outflow boundaries across north-
central Illinois.  Most high-res models suggest only isolated and
very disorganized convection today: however, think storms will be
more numerous further north closer to the boundaries.  As a result,
have carried chance PoPs along/north of I-74 from late morning
through the afternoon.  Further south, have only gone with slight
chance PoPs across the remainder of the area with high temperatures
mainly in the lower 80s.

Any storms that fire today will quickly dissipate by early evening,
followed by dry conditions through the night.  As upper wave moves
further away and ridge of high pressure builds in from the
northwest, mostly sunny and dry weather is expected on Sunday with
highs reaching the lower to middle 80s.

.LONG TERM...(Sunday through Friday)
ISSUED AT 332 AM CDT Sat Jul 30 2016

Upper ridge currently in place over the Desert Southwest will
gradually shift eastward next week. Main question will be how
strongly the ridge will build across central Illinois, as that will
have a big impact on PoPs.  GFS has consistently shown a weaker
ridge, keeping the area in the proverbial "ring of fire" around the
periphery of the ridge.  Meanwhile, the ECMWF has shown a stronger
500mb high, resulting in warmer/drier conditions by mid-week. Latest
GFS/GEM seem to be trending toward the ECMWF, so confidence is
growing that early week rain chances will give way to hot and mainly
dry conditions by Wednesday/Thursday.  Before the ridge builds in
sufficiently though, the potential exists for nocturnal storm
complexes beginning Sunday night.  GFS/ECMWF/GEM are all in good
agreement with this first complex...keeping it west of central
Illinois until early Monday morning.  Have therefore focused highest
PoPs across the Illinois River Valley Sunday night, with dry
conditions expected further east across the E/NE CWA.  Scattered
showers/thunder will prevail across the entire area on Monday,
before another nocturnal system may develop/move across central
Illinois Monday night into Tuesday.  Have carried high chance PoPs
accordingly.  After that, ridge builds further eastward and rain
chances decrease by Wednesday.  Temperatures will start out in the
middle 80s on Monday, but will climb into the lower 90s by Thursday
as upper heights rise.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 645 AM CDT Sat Jul 30 2016

Fog and low clouds will affect central IL terminals until around
14Z before daytime heating dissipates fog. Expect areas of IFR/LIFR
vsby and cigs especially along and just north of a KSPI-KCMI line.
Cigs will likely lift to MVFR category after 14Z and VFR by around
17Z. Scattered shra/tsra are possible from around 18Z-03Z,
especially at KPIA, KBMI, & KCMI. Clearing skies and light winds
will bring a chance for fog redeveloping overnight and have
included 3sm vsby after 09Z in TAFs for now.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Onton



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