Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 301155
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
655 AM CDT FRI SEP 30 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 308 AM CDT Fri Sep 30 2016

07z/2am water vapor imagery shows center of persistent upper low
centered over central Kentucky.  Scattered showers continue to pivot
around the low, with the most concentrated area of rain immediately
to the north of the center over southern Indiana/far northern
Kentucky.  Based on recent radar loops, have opted to go with likely
PoPs along/south of a Paris to Effingham line early this
morning...with rain chances steadily decreasing further west toward
the Illinois River Valley.  As the day progresses, additional
showers will develop further west, resulting in increasing PoPs
across the remainder of the KILX CWA.  With upper low slowly lifting
back northward and lapse rates steepening, MUCAPE values are progged
to reach the 600-1000J/kg range across the east later today.  As
a result, have mentioned isolated thunder along/east of I-55 this
afternoon.  Given extensive cloud cover and scattered showers,
high temperatures will once again remain in the middle to upper
60s.  Showery weather will continue tonight, although areal
coverage will decrease due to loss of daytime instability.  Will
carry chance PoPs everywhere, with lows dropping into the middle
50s.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 308 AM CDT Fri Sep 30 2016

Upper low will continue to lift northward into northern Indiana by
Saturday evening.  With this feature still in the vicinity, am
expecting scattered showers and cool conditions to persist through
Saturday.  After that, all model solutions track the low into the
Great Lakes by Sunday, resulting in rising heights across the
Midwest and a return to warmer/drier conditions for early next week.
With increasing amounts of sunshine, high temperatures will reach
the lower 70s on Sunday, then the middle 70s by Monday.

The next big weather question will revolve around how quickly a
western CONUS trough can translate eastward next week.  The speed of
this system will likely be impacted by Hurricane Matthew as it
tracks northward off the North Carolina coast by the middle of next
week.  Given the expected track/intensity of Matthew, think a slower
eastward progression of the trough is prudent.  As a result, have
maintained dry conditions through Tuesday night, with only low
chance PoPs arriving across the western CWA by Wednesday.  Wednesday
night into Thursday appears to be the primary time frame for precip
chances as the trough and its associated cold front gradually make
their way eastward into Illinois.  Before the precip arrives
however, a couple of very warm days with temperatures well into the
70s and perhaps to around 80 degrees will be on tap for Tuesday and
Wednesday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 654 AM CDT Fri Sep 30 2016

An occluded low pressure system churning to the SE of our
forecast area will keep clouds and periodic showers in the TAFs
over the next 24 hours. IFR clouds will dominate the first few
hours of the 12z TAFs, with LIFR at BMI. Daytime heating will lift
the LCL, so that MVFR conditions prevail for the rest of the day.
There may be enough mixing to break a few holes in the clouds this
afternoon, but expect overcast conditions for the most part. IFR
clouds and MVFR visibility in fog will likely develop tonight as
the low pressure center lifts north into Indiana.

Rain chances will be hard to pinpoint, but the latest HRRR and
RAP models point toward a band of steadier rains arriving from the
east later this afternoon into the evening. Have focused that time
frame for prevailing rain for CMI and DEC. Outside of that, have
kept VCSH at the other terminals.

Surface winds will remain out of the north-northeast over the next
24 hours, with wind speeds increasing to 10 to 15 kts today. Look
for an occasional gust up to 20 kts at times, especially during
any showers that affect the TAF sites.

&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Shimon


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