Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 180522

Area Forecast Discussion
National Weather Service Lincoln IL
1222 AM CDT Fri Aug 18 2017

Issued at 915 PM CDT Thu Aug 17 2017

Slightly cooler and less humid air is filtering into central and
southeast Illinois in the wake of a weak cold front. Neutral
upper-level flow and surface ridging will also build in behind the
front. This scenario supports quiet weather across the area
tonight. Going forecast is in good shape with only minor hourly
tweaks needed at this time.


.SHORT TERM...(This evening through Friday)
ISSUED AT 306 PM CDT Thu Aug 17 2017

19z/2pm surface analysis shows a cold front advancing slowly
eastward across central Illinois, with the boundary essentially
along the I-55 corridor. Am watching a line of enhanced CU on
satellite imagery from Paris to Effingham for potential isolated
convective development over the next 2-4 hours. Have maintained
slight chance PoPs across the far E/SE KILX CWA into early evening
accordingly. Once the front passes, skies will become clear and low
temperatures will drop into the lower to middle 60s.

The next weather system of interest is already evident on water
vapor imagery over Montana and will be approaching Illinois from
the northwest by Friday afternoon. Based on 12z model consensus,
think any convection associated with this feature will remain
along/west of the Mississippi River until Friday evening. As a
result, am expecting a mostly sunny and dry day on Friday with
highs in the middle 80s. Scattered showers and thunderstorms will
develop Friday night as the upper wave arrives across the area.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 306 PM CDT Thu Aug 17 2017

A few showers may linger into Saturday morning across the far
E/SE, but these will quickly exit as the upper wave tracks into
the Ohio River Valley. The remainder of the weekend is expected to
be dry, with temperatures climbing into the upper 80s to around 90
degrees by Sunday. The next system will come into the picture
early next week, bringing rain chances back to central Illinois
by late Monday into Tuesday. As is typically the case, the GFS is
quicker and more bullish with precip than the ECMWF. Model
consensus suggests the strongest lift and deepest moisture will
coincide on Tuesday when the wave passes through the region. Have
therefore kept PoPs confined to the north and in the chance
category for Monday/Monday night...before spreading them further
south and increasing them to high chance to likely on Tuesday.
After that, upper troughing digging across the Great Lakes will
bring cooler/drier weather by next Wednesday and Thursday.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1222 AM CDT Fri Aug 18 2017

VFR conditions expected to prevail the next 24 hours. Pressure
gradient around a low over Lake Superior will bring winds west up
to around 10 knots or so by late morning, mainly from KPIA-KCMI,
before settling late afternoon. An approaching cold front will
bring scattered thunderstorms into parts of central Illinois late
in the period.




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