Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 272346

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

.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 00Z TAFS through 00Z Friday evening)
Issued at 646 PM CDT Thu Oct 27 2016

MVFR ceilings continue mainly east of a KBMI-K1H2 line this
evening with the area of low ceilings eroding from the west as low
level SSW flow develops on the west side of high pressure crossing
eastward over the area. Under the clearing area...nocturnal
cooling combined with lingering low level moisture should result
in fog forming overnight as several models depict. 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 afternoon.


.ILX Watches/Warnings/Advisories...



LONG TERM...Shimon
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