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397
FXUS63 KILX 221035
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
535 AM CDT Thu Jun 22 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 242 AM CDT Thu Jun 22 2017

Central Illinois was located between a couple notable features
early this morning. Small MCS`s across Iowa and western Wisconsin
will track to our north, although radar was showing some tiny,
light showers widely scattered across our area. Meanwhile to our
south, some of the high clouds associated with Tropical Storm
Cindy have spread into central and southern Illinois, although the
closest rainfall with it was near the southern Tennessee border.
This area of rain will be tracking northward today, with the
high-resolution model guidance suggesting an arrival around midday
over areas south of I-70. Main threat will remain across the
southeast CWA into the afternoon hours, with a few stray storms
possible as far north as I-72. With lower clouds and more rain,
in that area, highs should be confined to the lower 80s, while
areas further north around Galesburg and Peoria may be nudging 90.

The remnants of the tropical system will lift northeast into
southern Arkansas overnight, while a cold front in the northern
stream descends into the Illinois River valley after midnight.
Central part of the CWA should get off easier tonight in between
these systems, but rain chances ramp up after midnight with the
front, as well as with an additional surge ahead of the tropical
remnants. The NAM keeps the heaviest rains closer to the Ohio
River, while the GFS and ECMWF bring the heavier axis just south
of I-70. Have maintained the high PoP`s in the northwest and
southeast corners of the CWA, while refining the general trends.
Severe-wise, primary severe weather threat appears to be a bit
further north/northwest due the late arrival of the front in our
area, but parts of the expected MCS may dip into the far northern
CWA late tonight.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 242 AM CDT Thu Jun 22 2017

Most of the evening models have picked up the speed of the front`s
passage across the forecast area on Friday, and areas from about
Danville-Taylorville northwest should be dry by midday. With the
tropical remnants lifting northeast into the Tennessee Valley,
the high rain chances will continue over the far southeast CWA
through the afternoon hours. The heaviest precipitation should
stay closer to the Ohio Valley, but overall rainfall of a half to
1 inch appears likely over the southeast CWA.

A broad upper trough still appears likely over the Mississippi
Valley through the weekend through about Tuesday, when the
western ridge begins to shift eastward. Most of the shortwaves
within this trough will be swinging through the Upper Midwest, and
with the main threat of any precipitation generally closer to the
Great Lakes. The GFS features a bit more of a southern track on
these waves, with some isolated showers over the northern CWA
during the afternoon hours of Sunday and Monday. Monday would
seem the more likely of the two, as a cold pocket at 500 mb
(temperatures down to -22C) moves across the Great Lakes. In any
event, only slight chance PoP`s were included north of I-74 at
this time. Highs should only be in the mid 70s in most areas from
Saturday into Monday as a lobe of cooler air swings across the
Midwest. However, a return to more seasonal highs is expected by
mid week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 534 AM CDT Thu Jun 22 2017

Initial concern will be with an area of MVFR ceilings advecting
northward this morning. These lower clouds are expected to start
affecting areas from KSPI-KCMI in the 20-23Z time frame, but
further northwest around KPIA it may take until mid evening to
arrive. Conditions will slowly degrade late this evening and
overnight, with potential for IFR conditions over eastern Illinois
and low MVFR ceilings further west. Outside chances for some
convection early this evening near KCMI, but main risk will be
further south. However, as a cold front approaches from the
northwest after 06Z, showers and thunderstorms will accompany it.
Have included some mention of rain at all sites late in the
period, but limited VCTS mention to KPIA/KBMI for now.

&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Geelhart