Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 011513
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1013 AM CDT SAT OCT 1 2016

.UPDATE...
Issued at 1013 AM CDT Sat Oct 1 2016

Upper low has reached northeast Indiana late this morning, with
lobes of energy rotating around the northwest flank of the low.
Decent area of showers extends from near Milwaukee southward to
Danville as of 10 am, but areas further west mostly dry with some
light showers or drizzle from Galesburg to Springfield. Main focus
into the afternoon will remain over the northeast CWA as the waves
of energy get some enhancement off the lake. Have updated the PoP
trends to concentrate the highest chances from around
Bloomington-Danville with mainly scattered showers elsewhere.
Little change needed to temperatures at this time.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 324 AM CDT Sat Oct 1 2016

Short term will still be dominated by the slow moving low pressure
system just east of Illinois. The upper low center is expected to
gradually lift north through eastern Indiana today, while the
surface low center generally remains in western Indiana along the
Illinois border. Various lobes of energy are depicted to rotate
around the upper low through the day, with plenty of low level
moisture available to produce periodic rain showers and drizzle.
Low clouds, fog and drizzle will start the day, with periods of
heavier drizzle or showers at times the rest of the day. While the
better chances appear to reside in eastern Illinois, showers look
to hold together into western Illinois per the latest HRRR and RAP
model updates. Rainfall amounts should generally remain less than
a quarter inch, with most locations around a tenth of an inch. The
potential for thunder looks low, but a few rumbles of thunder
could develop this afternoon east of I-57. Diurnal temperature
swings will be held in check by the overcast skies, as high temps
only climb 10 to 12 degrees above morning lows. Highs should reach
the upper 60s to around 70 today.

Tonight, showers and drizzle should dissipate overnight, as the
surface and upper lows pull farther away to the northeast. Stratus
clouds will likely linger through at least Sunday morning. Patchy
fog will be possible as well, due to plenty of boundary layer
moisture. Low temperatures will be in the middle 50s.

.LONG TERM...(Sunday through Friday)
ISSUED AT 324 AM CDT Sat Oct 1 2016

Large 564 dm 500 mb low over southeast Indiana will lift up
toward Detroit by sunrise Sunday, and into nw NY by dawn Monday.
IL will still be in a cyclonic flow on Sunday, as upper level low
pulls way from the region, though chances of rain showers to lift
ne of CWA on Sunday. Mostly cloudy skies expected most of the day
Sunday, though skies could become partly sunny during Sunday
afternoon especially sw of I-74 as nw winds bring in some drier
air. Highs around 70F from I-74 northeast and in the lower 70s sw
of I-74 on Sunday. Partly cloudy skies Sunday night with lows in
the low to mid 50s as weak surface high pressure ridge settles in.

Upper level ridge moves into the Great Lakes region on Monday and
provides a nice day to central/southeast IL with partly to mostly
sunny skies, light winds and seasonable highs in the low to mid 70s.
Fair skies Monday night with lows in the mid 50s. Upper level ridge
shifts east into New England on Tuesday, while cutoff upper level
low off the Pacific nw coast tracks into the northern high plains.
Another nice early fall day expected for IL with mostly sunny skies
on Tue and southeast winds bringing milder highs in the upper 70s.
Dry conditions expected to continue through Tue night with lows in
the upper 50s to around 60F.

00Z models still differ with movement of cold front eastward across
IL around Thursday. ECMWF model is keep CWA dry yet on Wed, while
GEM brings qpf into the IL river valley and GFS has qpf as far east
as I-55. Category 5 Hurricane Matthew with winds of 160 mph at 13.3N
and 72.5W is forecast to track northward into the Bahamas during Wed
and this may tend to slow the upper level trof and cold front west
of IL then. Have dry conditions over IL on Wed and 20-40% of showers
and thunderstorms by Wed afternoon from I-55 west with highest pops
of 30-40% nw of IL river. Highs in the upper 70s west of the IL
river on Wed with lower 80s east of the IL river. Have increasing
pops from west to east during Wed night with approaching of cold
front, with likely pops over IL river valley. Then this cold front
appears to move over IL on Thu as it weakens somewhat. Continued 40-
50% pops on Thu with highs in the lower 70s over IL river valley and
upper 70s over the Wabash river valley. Temps continue to cool
behind the front on Fri/Sat with highs in upper 60s/lower 70s on Fri
and mid to upper 60s on Sat. Dry conditions expected Fri and
Saturday with surface high pressure moving into from the west.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 637 AM CDT Sat Oct 1 2016

The large upper low over southern Indiana will finally make some
slow progress to the north today. An elongated surface low in
eastern Indiana will bring IFR conditions to the forecast area
this morning, along with drizzle and showers. As the low shifts
north through Indiana, the showers and drizzle threat will hold
over the area thru the afternoon with a typical lifting of the
cigs to MVFR. As the low shifts away from our area tonight, MVFR
cigs are expected to continue, with ceilings dropping to IFR again
after midnight. Plenty of surface moisture will set the stage for
some MVFR fog as well. Surface winds will start out from the N-NE
this morning, then begin to shift around to the NW this afternoon
and evening. Wind speeds will generally remain below 10 kt through
the period, under a weak surface pressure gradient and limited
mixing down of the mid-level winds.


&&

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

$$

UPDATE...Geelhart
SHORT TERM...Shimon
LONG TERM...07
AVIATION...Shimon



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