Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 192128
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
328 PM CST Fri Dec 19 2014

.SHORT TERM...(Tonight)
ISSUED AT 328 PM CST FRI DEC 19 2014

20z/2pm visible satellite imagery continues to show a large break in
the overcast extending from southeast Iowa across much of central
Illinois into Kentucky. With high pressure directly overhead and
only very light low-level winds, partly to mostly clear conditions
will persist through the evening hours.  As the high begins to shift
eastward, a southerly return flow will gradually develop late
tonight into Saturday, allowing the low clouds currently across
Iowa/Missouri to spill back into the area.  End result will be a
mostly clear start to the night, with overcast conditions expected
across the board by dawn Saturday.  May also see some patchy fog
west of the I-55 corridor late tonight as low-level moisture
increases, but am not expecting any major restrictions to
visibility.  Due to the initially mostly clear skies and light
winds, another cold night is expected with low temperatures
bottoming out in the lower to middle 20s.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 328 PM CST FRI DEC 19 2014

A rather quiet weekend is on tap across central and southeast
Illinois, but weather activity will be on the upswing heading into
the Holiday work week.

Model agreement is good through the weekend with mostly neutral
upper-level flow and high pressure expected to be the dominant
player at the surface. A week wave, currently pushing east across
the central Plains, will cross the area early Saturday. However, the
forcing appears too weak, and moisture depth too shallow, to warrant
a mention of any precipitation.

A strong, slow moving system will impact the area from Monday into
Christmas Eve. We will remain on the warm side of the system through
Tuesday, with all precipitation initially expected to fall in the
form of rain. Temperatures ahead of the system will also average
nearly 10 degrees above normal for late December.

The colder air on the back side of the deepening storm system will
arrive for Tuesday night into Christmas Eve. This would support any
remaining precipitation changing over to snow. At this point, the
threat for significant snowfall on the back side of the system seems
low, but some light snow accumulation is likely. The model
agreement/run-to-run consistency is still a little shaky heading
into midweek, so future model trends will need to be monitored very
closely.

Another system is progged to arrive by late in the week, generally
Friday into Saturday. However, model consistency with this system is
poorer than the first, so confidence in the ultimate outcome is not
very high.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1158 AM CST FRI DEC 19 2014

Latest satellite imagery continues to indicate mostly clear skies
across much of central Illinois late this morning, with VFR ceilings
persisting at only KSPI. Further west, MVFR/IFR ceilings blanket
Iowa/Missouri. With high pressure directly overhead, low-level
winds are quite light and will remain light until the high begins
to shift off to the east later tonight into Saturday. At that
time, return flow on the back side of the slowly departing high
will allow lower clouds to spill back into the area from the W/SW.
Have therefore gone with VFR conditions across the board this
afternoon/evening, followed by a gradual return of MVFR ceilings
overnight into Saturday morning. Have lowered ceilings to around
2500ft and introduced restricted visbys down to 4sm between 13z
and 16z accordingly.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Barnes
LONG TERM...Bak
AVIATION...Barnes






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