Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 231800

Area Forecast Discussion
National Weather Service Lincoln IL
100 PM CDT TUE AUG 23 2016

Issued at 1102 AM CDT Tue Aug 23 2016

Surface ridge axis off to the east, and southerly winds dominate
Central Illinois this morning. Warm and muggy conditions expected
with increasing clouds as a wave to the southwest edges closer to
the region. Forecast is going well and no updates are anticipated
at this time.


.SHORT TERM...(Today and tonight)
ISSUED AT 302 AM CDT Tue Aug 23 2016

High pressure will move off to the east today, keeping southerly
winds over the area. The southerly winds will bring warm air and
moisture advection into the region, west of the CWA. Warm air
advection precip is expected to develop along a frontal zone and
begin to push into southwest and west central IL this evening. As
the night progresses, expecting this type of precip to continue to
advect further east across the CWA after midnight. GFS looks a bit
fast and too far east with the precip tonight, so like ECMWF and NAM
with highest pops being northwest of I-55 late tonight, though a
chance of precip will spread east as well during the night.

Temps will be a degree or two warmer than yesterday, while overnight
lows will be warmer, only falling to around 70...due continue
southerly winds of around 10kts and continue precip and clouds.
Coolest temps tonight will be in the east.

.LONG TERM...(Wednesday through Monday)
ISSUED AT 302 AM CDT Tue Aug 23 2016

Morning MCS activity will be lifting northeast on Wednesday as the
upper trough moves eastward from Illinois. Main cold front continues
to be progged by the models to not fully pass through the forecast
area until late Thursday, so an extended period of high chance or
likely PoP`s will remain in the forecast through much of Thursday.
Hefty CAPE`s above 3000 J/kg return by Wednesday afternoon, helping
to fuel some afternoon redevelopment. Bulk shear from 0-6km
generally at or below 30 knots through the afternoon, with a more
maximized and higher core arriving late evening when the CAPE`s are
not quite as high, so severe weather threat continues to be
marginal. Abundant precipitable waters over 2 inches will lead to
efficient heavy rains in the stronger storms, though.

Strong upper high over the Tennessee Valley will hold firm through
late week, with central Illinois on the periphery. This will keep
the cooler air behind the front up closer to the Great Lakes, with
some modest cooling for Friday and Friday night. Dew points will be
on the increase again by Saturday though, as the next shortwave
pushes east through the Plains. Highest PoP`s during the day on
Saturday will be across the western half of the forecast area, with
a drier easterly flow persisting near the Indiana border through
late afternoon.

Beyond Saturday, the extended models start to diverge with respect
to the wave. The ECMWF is stronger with the wave and pushes the
associated surface boundary all the way through the area by Sunday
afternoon, while the GFS is much weaker and keeps any sort of
boundary to our north into early next week. The southeast upper
ridge remains quite firm and only drifts slightly east toward the
Carolinas this weekend, so would lean more toward the GFS at the
moment and its scattered thunderstorms.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1255 PM CDT Tue Aug 23 2016

Most of the cu field is to the NE, but a narrow strip of cu ahead
of a thicker cloud shield on vis sat imagery advancing through
Central Illinois ahead of the next weather system. This system
will move mid clouds into the region before sunset...and bring
showers and potential thunder after midnight. Keeping the forecast
relatively conservative for now, with drops to MVFR vis. Concern
that the cigs will also need to drop to MVFR status, especially
for PIA and BMI in the north. Southerly winds throughout.


.ILX Watches/Warnings/Advisories...


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