Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 112356
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
656 PM CDT Thu Sep 11 2014

.SHORT TERM...(Tonight)
ISSUED AT 259 PM CDT THU SEP 11 2014

Cold front just south of the Ohio River Valley this afternoon as
high pressure builds into the Midwest.  Northerly flow at the sfc
bringing unseasonably cool temps into the region, in stark contrast
to the weather of the last few days.  Cooler temperatures expected
to continue into the overnight hours.  With lows dipping into the
upper 40s across the nrn portions of the state...and low 50s before
dawn for much of Illinois.  Breaks in the cloud cover off to the
west not having much success in moving into the region.  As a
result, continued cloud coverage expected through the overnight
hours as llvl RH has remained trapped.  Both NAM and HRRR slow to
move clouds out, though some brief clearing is possible NW of the
Illinois River.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 259 PM CDT THU SEP 11 2014

Cool and cloudy conditions are expected again Friday as low level
northerly flow continues with a strong capping inversion at around
850 mb. An upper level shortwave will be rapidly approaching from
the west. The axis of the shortwave expected to cross Illinois late
Friday evening to early Saturday morning...pushing another frontal
boundary through the region. Current model forecasts are fairly
consistent keeping precipitation with this feature mainly north of
I-72...and modest amounts around 0.10 inches or less. Have PoPs
beginning Friday afternoon west of I-55 as lift associated with the
approaching shortwave begins...then PoPs spread through most areas
I-55 northward Friday evening. The system moves rapidly east-
northeastward leaving a cool and dry weekend behind it...with highs
in the 60s and lows in the 40s...as high pressure settles over the
area.

The next chance for precipitation will be Monday as models
consistently track another broad trough through the midwest. Cool
dry northwesterly flow aloft is expected to follow for the remainder
of the week with little chance for any precipitation and below
normal temperatures continuing.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 656 PM CDT THU SEP 11 2014

MVFR clouds will prevail over the next 24 hours, with some
periodic IFR cloud heights possible late tonight and early Friday
morning. Subsidence under a cold dome of high pressure is keeping
a blanket of low moisture in place across much of the Upper
Midwest. A fast moving shortwave is triggering a narrow band of
showers across south-central Iowa, that are moving toward N IL.
No precip was included at PIA for now, as the trajectory of the
showers and forecast soundings do not look supportive of precip
that far south with this wave. As the upper trough rotates into N
IL tomorrow, coverage of showers will increase west of I-55. We
included a VCSH in the afternoon for all sites but CMI.

Winds will remain north to northeast over the next 24 hours, with
wind speeds climbing to around 10kt during the day, and
diminishing to 5-7kt at night.

&&

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

$$

SHORT TERM...HJS
LONG TERM...ONTON
AVIATION...SHIMON






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