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Area forecast discussion 
National Weather Service Lincoln Illinois
1229 PM CDT Wednesday Oct 7 2015

issued at 925 am CDT Wednesday Oct 7 2015

Visible satellite imagery at 9 am shows what's left of the low
clouds and dense fog across Coles, Edgar and southern Vermilion
counties. This will continue to shrink over the next hour, and
since the remainder of east central Illinois saw the fog lift an
hour or so ago, the advisory was allowed to expire. Otherwise,
little change was needed to the forecast, with partly cloudy skies
and most areas reaching the upper 70s.


Short term...(today)
issued at 314 am CDT Wednesday Oct 7 2015

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 north/northwest 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 County Warning Area over
the next few hours. Hrrr has been consistently showing this signal
as confidence is high that dense fog will develop across
the east. 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 west/northwest 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)
issued at 314 am CDT Wednesday Oct 7 2015

00z Oct 7 models have slowed the approach of the next cold front by
about 6 hours...with the boundary now remaining well west/northwest of the
area through the day Thursday. As a result...have removed pops
across the northwest County Warning Area 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 frontal passage
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 Continental U.S. 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 18z tafs through 18z Thursday afternoon)
issued at 1229 PM CDT Wednesday Oct 7 2015

VFR conditions expected through much of the next 24 hours. As
high pressure axis shifts eastward, the light and persistent
north/northeast flow will become more south-southwest after 06z
and increase to near 10 knots by Thursday morning. Currently
thinking that any fog that forms would mainly be south of kcmi,
and have only kept the tempo MVFR group at that site.


Ilx watches/warnings/advisories...


short term...Barnes
long term...Barnes

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