Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 120215

Area Forecast Discussion
National Weather Service Lincoln IL
915 PM CDT Fri Aug 11 2017

Issued at 905 PM CDT Fri Aug 11 2017

The weak cool front the brought the showers and thunderstorms to
parts of our area last night into early this morning has pushed
into extreme southeast Illinois this evening with isolated showers
and thunderstorms confined mainly to its south. Further north,
the cumulus clouds for the most part have dissipated with the loss
of daytime heating which should allow temperatures to drop into
the mid 50s to around 60 by dawn Saturday. A nice day shaping up
on Saturday as the fair weather system drifts southeast into the
Midwest bringing plenty of sunshine, light winds and afternoon
temperatures around the 80 degree mark. Current forecast has a
good handle on the late evening and early morning trends, so other
than some minor tweaks to the evening temperatures in the grids
and taking precip out in far southeast Illinois, the rest of the
forecast looks good. Should have the update out by 920 pm.


.SHORT TERM...(This evening through Saturday)
ISSUED AT 301 PM CDT Fri Aug 11 2017
A low pressure center is making its way through the Great Lakes
this afternoon, and the associated cold front has slipped south of
Interstate 70 and out of ILXs forecast area. In the wake of the
front, an expansive cu field has developed, but expect to lose the
fair weather clouds quickly around sunset. Overnight will be
cooler as clear skies and light winds in general set up for some
radiational cooling more so than a major difference in airmasses
behind the front. To that end, tomorrow will be partly
cloudy/mostly sunny, and the temperatures will be fairly similar
todays, in the upper 70s/near 80.

.LONG TERM...(Saturday night through Friday)
ISSUED AT 301 PM CDT Fri Aug 11 2017

Mild and quiet weather lasts through the weekend as Sunday more or
less repeats Saturday. High pressure remains in place over the
Midwest for most of the forecast. Potential trouble spots in the
forecast are Sun night Monday when a series of two shortwaves
ripples through. GFS and ECMWF have both become less amplified and
the first wave passes through dry with little impact. Mon/Monday
night, the GFS continues to persist with the second wave, bringing
a run of precip mainly in the southern tier of IL and points
south. Monday into midweek remains mild and dry for Central IL as
a slow warming trend kicks in midweek as the winds slowly come
around to more southerly to end the forecast. Whereas the first
half of the week is dominated by a low passing over eastern Canada
with little amplification in the CONUS... the second low moving
in later in the week has more of an impact, developing showers and
thunderstorms in the Midwest for Wednesday and Thursday.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 605 PM CDT Fri Aug 11 2017

VFR conditions are expected across the TAF area through Saturday
as high pressure drifts in from the northwest. Cumulus field late
this afternoon starting to show signs of dissipating on the latest
satellite loop and we expect that trend to continue into early
this evening. Forecast soundings indicate few-sct cumulus will
develop by late Saturday morning, especially along and east of
the I-55 corridor with bases from 4000-5000 feet. Surface winds
will not be a factor through this forecast period with light
northwest winds expected tonight and northerly flow forecast on
Saturday at 7 to 12 kts.




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