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FXUS63 KILX 070814

314 AM CDT WED OCT 7 2015

.SHORT TERM...(Today)

As has been the case over the past couple of nights...fog is once
again developing across portions of central Illinois early this
morning.  08z/3am surface obs show widespread dense fog across
northeast Illinois into northwest Indiana.  With surface ridge axis
still in place across the region...low-level flow is generally from
the N/NW as evidenced by area 925mb VAD wind profilers.  Given this
trajectory...the current area of fog will likely advect/develop
slowly southward across mainly the eastern half of the KILX CWA over
the next few hours.  HRRR has been consistently showing this signal
as confidence is high that dense fog will develop across
the E.  Based on HRRR forecast and latest obs...have decided to
issue a Dense Fog Advisory through 14z for all locations
along/northeast of a Marshall line.
Mid-level cloudiness pushing slowly in from the W/NW should prevent
areas further west from seeing quite as much have only gone
with patchy fog in the forecast along/west of I-55.  The fog will
gradually dissipate by mid-morning...with skies becoming partly to
mostly sunny during the afternoon.  Resulting high temperatures will
be similar to yesterday in the middle to upper 70s.


.LONG TERM...(Tonight through Tuesday)

00z Oct 7 models have slowed the approach of the next cold front by
about 6 hours...with the boundary now remaining well W/NW of the
area through the day Thursday.  As a result...have removed PoPs
across the NW CWA during the morning and have limited chance PoPs to
locations along/northwest of I-55 in the afternoon.  With partly
sunny skies and strong/gusty southwesterly winds ahead of the
front...afternoon highs will soar into the lower 80s across the
board.  Better rain chances will arrive Thursday boundary
interacts with an increasingly moist low-level airmass characterized
by surface dewpoints in the upper 50s and lower 60s.  Due to the
slower arrival of the front after dark...daytime instability will be
waning with MUCAPES of less than 500J/kg.  Despite weaker
instability than previously forecast...think increasing shear and
strong convergence along the boundary will be enough to trigger
scattered thunderstorms.  Have carried likely PoPs with FROPA
Thursday night.  Have also lingered rain chances a bit longer into
Friday morning...especially along/south of I-70.  Front is progged
to drop into the Ohio River Valley by Friday afternoon...ending the
rain chances and introducing much cooler weather with highs
remaining in the middle to upper 60s.

After a chilly Friday night with lows in the middle 40s and a
seasonable day on Saturday with afternoon highs in the 60s...another
warming trend will get underway early next week.  Rising upper
heights across the central CONUS will help temps rebound well into
the 70s by Sunday.  Models are not in particularly good agreement
with the timing of the next weak cold front...with the latest GFS
speeding it up by about 12 hours and now bringing it through central
Illinois on Monday.  Regardless of the timing...little to no low-
level moisture will be will continue with a dry
forecast through the remainder of the extended.  Have however cooled
highs on Monday from the lower 80s back into the middle to upper 70s
due to the faster arrival of the front.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)

High pressure settling over Illinois tonight has allowed winds to
taper off. Mid-level clouds to the northwest are advecting into
the state as well and are limiting some of the potential for
radiative cooling. latest short-range models, the 03z RAP and 03z
HRRR in particular, still suggest fog development along and east
of U.S. Highway 51. Though the development isn`t as far west as
the past two nights there is more consistency between the models.

Will bring KCMI down to LIFR conditions for a brief time around
sunrise. Vsbys are a bit more questionable at KBMI and KDEC but a
few hours of IFR still seems a good bet. As the clouds develop
southeast, mesoscale models suggest some improvement at KBMI by
11z and KDEC by 12z.

Dew Point spreads are currently higher at KPIA and KSPI as they
have been more influenced by incoming mid-level cloudiness.

Surface high should remain over the state on Wednesday keeping
winds light through the TAF valid period.


DENSE FOG ADVISORY until 9 AM CDT this morning for ILZ038-



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