Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 280450

Area Forecast Discussion
National Weather Service Lincoln IL
1150 PM CDT THU OCT 27 2016

Issued at 825 PM CDT Thu Oct 27 2016

High pressure centered over eastern Illinois with skies clearing
to the west combined with a moist boundary layer should result in
patchy fog forming over much of central IL overnight. Dewpoints
this afternoon and evening have been generally in the low to mid
40s and temperatures should be easily able to drop to this level
under clearing skies. 00Z KILX upper air sounding shows a fairly
deep moist mixed layer which should be favorable for fog as well.
Have therefore increased fog coverage overnight in evening


.SHORT TERM...(This evening through Friday)
ISSUED AT 254 PM CDT Thu Oct 27 2016

Weak high pressure starts to move into the region this evening.
Low level clouds that have persisted through the day have limited
diurnal mixing and the dewpoints have remained in the low to mid
40s, with yesterdays rainfall likely enhancing the RH near the
surface.  Satellite imagery is beginning to show a clearing trend on
the western border of IL.  A cool overnight low is expected, and
with clearing skies and winds slowly weakening under the surface
ridge axis...there is a chance for some patchy fog through much of
the Midwest.  Tomorrow, WAA starts to kick in with more southerly
winds and midlevels warming to 13-15C at 850mb.  Max temps tomorrow
should be unseasonably warm again...into the low 70s...with
increasing winds/gusts through the afternoon as the pressure
gradient reestablishes over the region.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 254 PM CDT Thu Oct 27 2016

Windy conditions will start off the extended forecast as mixing of
strong low level winds to the surface produces sustained southwest
winds of 20-25mph and gusts to 35 mph during the evening. Typical
decoupling of the boundary layer winds may reduce sustained winds
somewhat, but feel that enough mixing will occur to produce the
gusty conditions. Have trended on the higher side of the guidance
wind forecast as a result. The warm southerly winds will keep low
temps Friday night much above normal, as temps bottom out in the
low 60s west of I-55, with mid to upper 50s east of I-55.

A cold front will make progress toward N Illinois on Saturday, as
breezy conditions continue into early afternoon. High temps will
climb through the 70s, with some low 80s possible in our SW counties
toward Jacksonville/Springfield. The cold front is expected to
progress south through central IL Saturday night into Sunday
morning, with a few showers possible Saturday night north of a line
from Canton to Bloomington. The front will only have limited
moisture the farther south it progresses, so precip should end by
Sunday morning. Cooler temps will result from the cold FROPA, as
high temps on Sunday range from the low 60s north of Peoria, to the
low to mid 70s south of I-70.

The extended models are in good agreement that dry conditions will
occur from Sunday night into Tuesday, as high pressure remains in
control of the weather. Monday will be another mild day, much like
Saturday, with high temps well into the 70s and even a few low 80s
possible. A cold front is forecast to move south into central IL
later Tuesday and stall out across our counties Tuesday night.
Limited moisture will prevent rain from developing on Tuesday.
Increasing clouds will limit high temps a little from Mondays
readings, with highs around 70 near Galesburg, and in the mid to
upper 70s south of I-70. Slight chances /20%/ of rain are in the
forecast for north of I-72 from later Tues night through Wednesday.
Model differences become more prominent Wed night and Thursday, with
ECMWF showing low pressure passing across the IL/WI border, with the
trailing cold front settling into central IL on Thursday. The GFS,
on the other hand, shows cool Canadian high pressure building into
the western Great Lakes including Illinois. The extended blend was
still more influenced by the wet ECMWF, and low chances of rain were
included in the forecast for Wed night and Thursday for now.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1150 PM CDT Thu Oct 27 2016

MVFR ceilings continue just east of the central IL terminals this
evening and should continue to move east. Under mostly clear skies
developing to the west...nocturnal cooling combined with
lingering low level moisture should result in fog forming
overnight as depicted by several models...especially west of I-57.
Fog should form earliest toward western Illinois. Have included
vsby reaching IFR category over all central IL terminals
overnight...although potential exists for lower visibility. Fog
should dissipate by late morning as increased southerly winds
develop...becoming 12-16 kts with gusts to around 20 kts by


.ILX Watches/Warnings/Advisories...


LONG TERM...Shimon
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