Area Forecast Discussion
Issued by NWS Central Illinois

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253
FXUS63 KILX 262349
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
649 PM CDT MON SEP 26 2016

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 250 PM CDT Mon Sep 26 2016

A cold front has moved through the Midwest and cooler and drier air
has settled in behind the front.  As a result, quiet weather and
cooler temperatures will continue through the overnight.  Tonights
lows will drop into the 40s...chilly by comparison to the weather of
late. Tomorrow will climb back into the upper 60s and low to mid
70s. Skies should remain clear as dry air and subsidence generally
rules.  The pressure gradient should keep the winds relatively
breezy out of the WNW.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 250 PM CDT Mon Sep 26 2016

Cooler than normal conditions will dominate the extended forecast,
as an occluded low pressure system drifts from the western Great
Lakes south toward Indiana/Ohio. The trend in the last couple of
runs of the models has been a farther west track of the low, closer
to Illinois. The ECMWF was the first to show that trend, and the
others have shifted in that direction. The EC remains the farthest
west with where the low lingers this week. It is also the last to
eject the low to the east next Saturday, although the Canadian and
GFS are not nearly as far behind as previous model runs.

The overall effect of a westward shift in the low placement would
mean much cloudier conditions in Illinois, at the very least. It
could also mean more days with the potential for periodic showers as
spokes of energy rotate around the cut-off low. We previously just
had slight chance PoPs on Tuesday night into Wednesday. However, the
influence of the EC model on the blended extended has prompted
additional slight chances for rain east of Bloomington to Decatur,
from Thursday night through Saturday. Friday shows the farthest west
expansion of rain chances, reaching all the way to Peoria and
Springfield. The forecast soundings are minimally supportive of rain
at any point this week, with a narrow layer of moisture in the lower
levels the primary moisture source. So rainfall amounts would be
trace amounts to a few hundredths of an inch for any areas that do
get rain this week and next weekend.

As mentioned previously, temps will linger below normal for the
first time in months. Morning lows on Wednesday will dip into the
upper 40s to low 50s. Mostly cloudy conditions on Wednesday will
keep highs that day limited to the mid to upper 60s, our coolest day
of the next week. The lingering proximity of the low just to the
east of Illinois the rest of the week will allow the chilly air mass
to linger. Highs Thursday through Saturday should remain in the
lower 70s, with lows in the lower 50s. At this point, more sunshine
is expected on Thursday, with increasing clouds Friday and Saturday.
With the forecast eastward departure of the low by Sunday, high
temps should climb a few degrees toward the mid 70s Sunday, with mid
to upper 70s next Monday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 647 PM CDT Mon Sep 26 2016

VFR conditions expected to continue across the central IL airports
next 24 hours through 00Z/7 pm Tuesday. Clear skies to prevail
through Tuesday. Any patchy fog that develops overnight will be
along the larger rivers like the MS and Ohio rivers and south
into KY, as airmass over central IL is too dry to support fog
formation. Breezy west winds will diminish quickly after sunset
and generally 4-9 kts after dark and veer more sw. Surface low
pressure dropping southward into Lake Superior by Tue afternoon
will set up a tight gradient over central IL again. Expect breezy
west winds by 15Z Tue with gusts of 17-23 kts by late Tue morning
and into Tue afternoon, before diminishing at sunset Tue toward
00Z/7 pm at end of TAF period.

&&

.ILX Watches/Warnings/Advisories...
NONE.

&&

$$

SHORT TERM...HJS
LONG TERM...Shimon
AVIATION...07



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