Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 230755

Area Forecast Discussion
National Weather Service Lincoln IL
255 AM CDT Sun Jul 23 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 255 AM CDT Sun Jul 23 2017

Earlier convection that occurred generally along and east of I-57
late evening and past midnight has largely pushed into Indiana as
of 2 am. Currently watching a large MCS advancing across Missouri.
Trajectory of this would generally keep it south of I-72 as it
begins to move into western Illinois, with the HRRR showing a
diminishing trend as the remnants make it over to about Flora and
Effingham toward 7 am. SPC mesoanalysis still showing CAPE`s over
3000 J/kg at this early hour ahead of the MCS, with dew points at
Springfield almost 80 degrees at 2 am. As the day goes on, the
highest CAPE will shift over into southeast Illinois, as some
lower dew points start to advect into areas northwest of the
Illinois River. However, as the cooler air lags further behind,
temperatures reaching the lower 90s will still result in
significant instability over the northern CWA this afternoon. Will
maintain the mention of scattered storms this afternoon and
evening across the forecast area, as the cold front settles across
the region. Can`t rule out a few severe storms as 0-6km shear is
modest over the area (around 30-35 knots).


.LONG TERM...(Monday through Saturday)
ISSUED AT 255 AM CDT Sun Jul 23 2017

Quiet weather will dominate the first few days of the work week,
as high pressure drifts across the Great Lakes. The northeast
circulation into our area should keep dew points in check, mainly
mid 60s, through Tuesday. After that, the Gulf moisture flow kicks
back in as the upper level high builds eastward back into the
mid-Mississippi Valley. A strong upper low, currently seen in
early formation over northern British Columbia, will keep the
ridge from amplifying too much over us, so after a quick shot of
hot and humid weather, the upcoming end of week looks more

The main concern for precipitation will be Wednesday night into
Thursday, as the cold front trailing the upper low moves through
the area. The GFS introduces some scattered storms as early as
Wednesday afternoon as a weak wave moves through, but the ECMWF
focuses on the main front itself late Wednesday night into
Thursday. In either case, it should take until late Thursday
evening before the front fully crosses the forecast area, and will
keep healthy chance PoP`s going south of I-72 into the evening.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1232 AM CDT Sun Jul 23 2017

Convection overnight should largely be south of the TAF sites.
Will need to watch KSPI for potential clipping of a convective
cluster that is currently tracking east through Missouri, but will
not include it at this point. Main threat for any storms will
generally be in the 22Z-02Z time frame. Have included a mention at
KPIA/KBMI initially, but threat further south is more uncertain
and will not mention from KSPI-KCMI yet.




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