Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 232247
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
547 PM CDT SAT JUL 23 2016

.SHORT TERM...(This evening through Sunday)
ISSUED AT 305 PM CDT Sat Jul 23 2016

19z/2pm surface analysis shows stationary frontal boundary extending
from southern Lake Michigan northwestward into the Dakotas.
Widespread convection is ongoing along/north of the boundary in
advance of a well-defined short-wave trough evident on water vapor
imagery over southern Manitoba.  Latest radar mosaic shows bulk of
thunderstorms focused from Minnesota and northeast Iowa across
Wisconsin...however a few radar echoes extending southwestward into
central Illinois will have to be watched as they may impact parts of
north-central Illinois this evening.  Models are handling the
convective evolution differently...with the WRF-ARW and GFS
depicting a dry forecast across the KILX CWA tonight...and the NAM
and HRRR showing the central Iowa convection tracking into the
northwest counties around Galesburg early this evening.  Based on
current radar/satellite trends...will follow the NAM/HRRR most
closely for the immediate short-term.  As such...have brought low
chance PoPs into the Illinois River Valley from the Canton area
northward early this evening...with the PoPs spreading eastward
along/north of I-74 through the overnight hours.  Further south
across the remainder of the CWA...have gone with a mostly clear
forecast with patchy fog developing along/southeast of a Paris to
Shelbyville line where dense fog was observed last night.

Cold front currently over the western Plains will push slowly
eastward on Sunday...eventually reaching the Mississippi River by
late afternoon.  Airmass ahead of the front will remain capped...as
evidenced by 700mb temps around 12C.  As a result, most model
guidance suggests dry conditions until the cap weakens late in the
day.  Have tailored PoPs accordingly to go with 30-40 PoPs
along/west of I-57 by afternoon...with only slight chance PoPs
further east and south.  High temperatures will once again reach the
lower to middle 90s...with heat index values topping out between 100
and 110 degrees.  Will continue the current Excessive Heat Warning
along/south of a Rushville to Danville line through Sunday
evening...and may need to include the northwest CWA in a headline
as well if current trends continue.

.LONG TERM...(Sunday night through Saturday)
ISSUED AT 305 PM CDT Sat Jul 23 2016

Cold front will sink into central Illinois Sunday night...bringing
scattered showers and thunderstorms to the entire area.  Have gone
with 50 PoPs across the board accordingly.  Boundary will then drop
slowly southward into the Ohio River Valley on Monday...gradually
taking the rain chances with it.  Have gone with chance PoPs
everywhere during the morning...then only south of I-72 by
afternoon.  Temperatures behind the front will be slightly
cooler...with highs dropping back into the middle to upper 80s.

High pressure will build into the Great Lakes for Tuesday, pushing
the front into Missouri/Kentucky.  While a warm/dry day will be on
tap across all of central and southeast Illinois, the front will
quickly begin to return northward as the high departs the region.
Models have continued the trend of bringing rain chances back into
central Illinois faster, with chance PoPs now in place across nearly
the entire area by Wednesday.  After that, the boundary will become
nearly stationary across the Midwest, resulting in daily rain
chances through the end of the week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 545 PM CDT Sat Jul 23 2016

Main concern will be with thunderstorm complex to our north and
whether any of our northern TAF sites will be affected later this
evening. Storms north of Moline tracking to the east and based on
the present movement, look to stay north of our area this evening.
However, a trailing band of showers stretched south of the storms
and may affect PIA and BMI in the 01z-04z time frame, so will hold
on to VCTS for those locations, otherwise, not expecting any
precip further south overnight. VFR conditions will continue thru
about 08z-09z before the potential of some patchy fog for our
forecast area. Any fog should lift with mainly VFR conditions for
the remainder of the forecast time frame. Surface winds will be
south-southeast tonight at 5 to 10 kts and then south to southwest
at 10 to 15 kts on Sunday.

&&

.ILX Watches/Warnings/Advisories...
Excessive Heat Warning until 7 PM CDT Sunday for ILZ040>057-
061>063-066>068-071>073.

Excessive Heat Warning until 7 PM CDT this evening for
ILZ027>031-036>038.

&&

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Smith



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