Area Forecast Discussion
Issued by NWS Central Illinois

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263
FXUS63 KILX 172359
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
559 PM CST Tue Jan 17 2017

.SHORT TERM...(This evening through Wednesday)
ISSUED AT 312 PM CST Tue Jan 17 2017

Very expansive shield of low clouds hanging on tight this afternoon
across the area, with the back edge of the clouds out around Omaha
and Topeka. Forecast soundings are not in too much of a hurry to get
rid of this, with a tight inversion through sunrise, although
lowering down to around 2000 feet by sunrise. NAM and GFS don`t
really show anything breaking through until closer to midday
Wednesday north of I-74, but do show the clouds starting to break
out toward mid-morning across the southwest CWA. Have kept skies
mostly cloudy through the morning, but most of the area should be
seeing some sunshine by afternoon as a ridge of high pressure drifts
eastward.

With the clouds sticking around tonight, have leaned more toward the
NAM MOS guidance, with lows mainly lower 30s, except mid 30s south
of I-70. Wednesday temperatures will be dependent on how fast the
low clouds break, but mid-upper 40s appear feasible, especially over
the southwest CWA.

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 312 PM CST Tue Jan 17 2017

High pressure moving off to the east will allow moisture to return
to the area just ahead of the next weather system coming out of the
southern plains. This moisture will interact with a
developing/deepening system to bring precipitation to the CWA
beginning Thursday and continuing into Thur night. Models have
shifted the track of this system little further northwest of
previous forecast, moving it across southern and southeast IL. With
the further northwest track and the warmer temps, all precip should
be in the form of rain through the period. Based on this track, also
seeing an increase in MUCAPE in southern IL, so have included schc
of thunder in southeast and eastern IL Thur afternoon through
Thursday night. As the surface trough and 500mb trough move through,
precip chances will continue Friday morning, but then should become
dry for the afternoon as things push off to the east and northeast.

Upper level flow will then become more southwest with an upper level
low pressure area to the west and northwest. This setup will
continue to bring warm air into the region and an isolated threat of
diurnal type precip...for into the weekend. For now, will just keep
small chances in the grids to account for this. The next main threat
of precip will begin Sunday and then increase through Sunday night
and Monday. Models show significant differences as to timing,
location, and intensity of the system so pops are in for more
periods than probably will occur. However, best chances look to be
Sun night and Mon.

Temps will warm rest of the week and into the weekend, with mildest
temps being Saturday when some spots could reach the lower 60s.
After the system on Sunday, temps will cool down a bit, but still
remain above normal for this time of year.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 559 PM CST Tue Jan 17 2017

Generally IFR ceilings can be expected to continue through the
overnight hours in most of central Illinois. Could see a brief
period of MVFR ceilings between 02-03z, but this should be short
lived. With a strong low level inversion and trapped moisture
should see patchy fog again overnight with visibility generally
between 3-5 miles. Could see some IFR fog at PIA and BMI for a
period of time just before and after daybreak.

A surface ridge axis, currently from eastern OK to extreme western
IA is projected to move into central IL around 15z tomorrow and
into eastern IL by 17-18z. This will finally bring VFR conditions
to the region with a light southwest wind.

&&

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

$$

SHORT TERM...Geelhart
LONG TERM...Auten
AVIATION...Miller



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