Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 010934

Area Forecast Discussion
National Weather Service Lincoln IL
334 AM CST Thu Dec 1 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 334 AM CST Thu Dec 1 2016

Mostly cloudy conditions are expected across central and southeast
Illinois through the period, as deep cyclonic flow remains in place.
The clouds will limit the diurnal temperature range anticipated.
Forecast daytime highs around 40 degrees are near normal for early
December, while overnight lows in the lower 30s are warmer than
normal. However, brisk west winds, at least through the daytime
hours today, will definitely make it feel rather chilly.


.LONG TERM...(Friday through Wednesday)
ISSUED AT 334 AM CST Thu Dec 1 2016

A large 529 dm 500 mb low pressure perched north of Lake Huron and
east of Lake Superior, is forecast to track east into southern
Quebec tonight and into Maine and Canadian Marinetimes by sunset
Friday. This will keep low clouds over central IL on Friday
especially ne half of CWA while more sunshine possible in southeast
IL and sw CWA. Weak upper level ridging moves into IL by Sat morning
while cyclone departs off the Canadian east coast. May be a brief
period of less cloud cover Friday night and Saturday morning, but
mid/high clouds to already be increase by Sat afternoon ahead of
next approaching wx system. So a mostly cloudy sky overall on
Saturday. Highs Fri and Sat will be similar to todays readings, near
40F from I-74 ne and lower 40s sw of I-74. Lows Friday night in the
upper 20s to near 30F.

Three weather system to impact IL from overnight Sat night through
Thu as a more active weather pattern returns to the area. 00Z models
are in better agreement with handling 1st wx system as northern
stream short wave/trof moves into the Midwest by sunrise Sunday
while a 555 dm 500 mb low moves into northwest Mexico. Moisture to
spread ne into central/southeast IL overnight Sat night into
Sunday as surface low pressure ejects ne from southeast Texas
keeping brunt of heavier qpf southeast of our CWA. System is a
quick mover and dry wx returns by early Sunday evening. Thermal
profiles support a mix of light rain and light snow over sw CWA
overnight Sat night and into northeast CWA during early/mid Sunday
morning, then turning to all rain by late Sunday morning and
Sunday afternoon. Little or no snow accumulations expected, a
dusting to less than a half inch on grassy surfaces north of I-74
Sunday morning. Lows Sat night in the lower 30s. Highs Sunday in
the lower 40s.

Dry weather expected Sunday night and Monday with partly to mostly
cloudy skies Monday and highs in the mid to upper 40s, mildest sw
CWA. Another surface low pressure ejects northeast from southeast
Texas and tracks into west TN by midnight Monday night and across
the Ohio river valley on Tue. This to mainly spread rain ne across
CWA during Monday night and then diminish by Tue afternoon. Lows Mon
night and Tue night in the mid to upper 30s. Highs Tue in the mid
to upper 40s central IL and around 50F in southeast IL.

A third wx system to impact area late Wed into Thu and bring much
colder air into the area Wed night and Thu. Models agree with a
large upper level trof digging into the Midwest and Ohio Valley
Wed/Thu and dropping temperatures. Highs Wed range from lower 40s nw
of IL river by Galesburg to the lower 50s in southeast IL. Highs Thu
only in the low to mid 30s. Lows next Thu night in the upper teens
and lower 20s. Models differ with handling storm system during
middle of next week, with GFS quickly bringing qpf into IL on Wed
while ECMWF model waits until late Wed into Wed night. For now will
bring in rain chances Wed afternoon from the west with highest pops
Wed night, as rain chances turn to snow chances from nw to
southeast as much colder air ushers in behind a strong cold front.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1122 PM CST Wed Nov 30 2016

A large area of MVFR ceilings in low cloud cover will continue to
affect central IL terminals through the 06Z TAF forecast period.
Upstream observations and model guidance suggest lower cigs will
affect KPIA-KBMI while cigs will remain above or close to MVFR/VFR
thresholds at KSPI-KDEC-KCMI. Winds W-WSW 8-14 kts through the




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