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Area forecast discussion 
National Weather Service Lincoln Illinois
659 am CDT sun Oct 4 2015

Short term...(today)
issued at 303 am CDT sun Oct 4 2015

Deep upper low currently centered over the southeast Continental U.S. Continues
to funnel low/mid-level moisture northwestward into central Illinois
this morning. 07z/2am infrared satellite imagery shows a low overcast
across the entire area, with the lowest clouds focused over the east/southeast
kilx County Warning Area. Other than a few very light returns from time to time,
radar has been largely dry over the past several hours. Surface obs
have been showing reduced visbys in the 2-4 mile range along/east of
I-57, indicative of areas of drizzle. High-res models tend to keep
any measurable precip further east across Indiana, perhaps spilling
into the Chicago area this morning. As a result, have opted to
remove pops in favor of patchy drizzle east of the I-55 corridor
through the morning hours. Forecast soundings show a gradual drying
trend as the day progresses, especially across the southeast where partial
clearing will occur by mid to late afternoon. Given some late day
sunshine, high temperatures will likely reach the lower 70s
along/south of I-70. Meanwhile further northwest where clouds will
persist through the entire day, highs will only reach the upper
50s and lower 60s northwest of I-55.

Long term...(tonight through saturday)
issued at 303 am CDT sun Oct 4 2015

As southeast low shifts offshore, heights will rise across the
Midwest Monday through Wednesday, resulting in increasing amounts of
sunshine and warming temps. Models continue to indicate 850mb temps
climbing into the 12-14c range, supporting highs well into the 70s.
The warmest day of the week will be Thursday when winds switch
around to the S/SW ahead of an approaching cold front. High temps
that day may reach the 80 degree mark in a few locations.

00z Oct 4 models are in relatively good agreement concerning the
late week frontal passage, although the European model (ecmwf) has slowed frontal passage by 6
to 12 hours from its previous runs. Meanwhile, the GFS remains
consistent in showing the front passing through central Illinois
Thursday night. Will continue to limit pops to areas west of I-55
during the day Thursday, then will spread high chance pops across
the entire County Warning Area Thursday night. Despite front coming through at an
unfavorable time of day for convection, ample moisture flowing
northward ahead of the boundary will produce modest instability
Thursday afternoon and night, with GFS showing MUCAPES of around
200j/kg and lifted index values of 0 to -2. Given instability and
strong convergence along the front, will mention isolated
thunderstorms as the front passes. Will linger low chance pops
across the southeast into Friday as the front drops into the Ohio River
valley. After that, cooler/drier conditions will be on tap for the
end of the week.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 652 am CDT sun Oct 4 2015

IFR/low end MVFR conditions are widespread across central Illinois
this morning. Northeasterly winds persist on the south side of an
approaching ridge axis, although winds are and should remain
significantly lighter than the past few days. Main forecast
concern is if/when skies will clear or cigs return to VFR levels.
There remains a fair amount of model disagreement in the details,
but have stayed fairly pessimistic given the current condtions and
low level moisture trapped beneath a strong inversion. Low level
wind trajectories do not support much low level drying taking
place either. However, did allow kcmi to improve to VFR by
tonight as they are closest to clearing that is evident on


Ilx watches/warnings/advisories...


Short term...Barnes
long term...Barnes

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