Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 181158
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
558 AM CST Sat Nov 18 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 345 AM CST Sat Nov 18 2017

09Z/3 am surface map shows a 993 mb low pressure deepening along
the KS/MO border with a frontal boundary extending ne across the
IL river valley. An area of showers and isolated thunderstorms was
north of I-72 and lifting ENE. Temperatures ranged from around 50F
along and nw of the IL river, to the lower 60s in southeast IL
from Pittsfield to Effingham to Lawrenceville south. Breezy south
winds se of I-55 were gusting in the 20s and bringing in the
milder/moist air mass with dewpoints in the low to mid 50s.

Will expand the wind advisory another row of counties northward
today with sustained winds of 25-30 mph and gusts of 40-45 mph
expected with strongest winds (nw) behind the cold front from 11
am to 5 pm. Wind advisory is in effect from 8 am to 9 pm today,
though strongest winds will be from late morning through sunset.
Models deepen surface low pressure ENE to 989 mb over ne IN by
18Z/noon, and 985 mb over Lake Erie by 00Z/6 pm and pulls cold
front from the IL river southeast through Lawrenceville early
this afternoon. Showers will continue to become more widespread as
deepening low pressure moves across area during this morning,
with thunderstorms also possible. SPC day1 outlook has marginal
risk se of Knox, Stark and Marshall counties, with a slight risk
of severe storms from Terre Haute to Flora se mainly during late
morning into early afternoon with passage of cold front. There is
a 5% risk of large hail and damaging winds gusts in marginal risk
area, while slight risk area in southeast IL has 15% risk of
damaging wind gusts and 2% risk of tornadoes. Rainfall amounts
average from a half to 1 inch today with highest amounts ne CWA.
Highs today range from around 50F from IL river nw early this
morning, to the mid to upper 60s in southeast IL from I-70 south.
Temperatures will fall behind the cold front, reaching 35-45F from
nw to se by sunset.

Will see rain mix with or change to light snow showers during the
afternoon northern CWA but no accumulations expected. Shower
chances linger east of I-57 early this evening, then dry rest of
the night as nw winds remain gusty through the night, strongest
during the 1st part of the evening when wind advisory is still in
effect. Much colder lows in the mid to upper 20s overnight, with
Lawrenceville near 30F.

.LONG TERM...(Sunday through Friday)
ISSUED AT 345 AM CST Sat Nov 18 2017

A quiet weather pattern expected during this time frame as dry
conditions return. Strong 980 mb surface low pressure will lift
over the St Lawrence Seaway during Sunday, while 1028 mb high
pressure settles into Texas and ridges into IL by Sunday
afternoon. This should lighten WNW winds to around 10 mph during
Sunday with return of sunshine as skies clear during overnight.
Highs Sunday only 35-40F and lows Sunday night of 25-30F.

Surface ridge over Texas settles over the TN river valley by
Monday morning and return ssw winds to moderate temperatures to
50-55F on Monday with mostly sunny skies. A dry cold front moves
se across CWA on Tue and starts to bring in cooler air especially
over the IL river valley where highs in the mid to upper 40s.
Milder 50-55F from Lincoln southeast. Lows back in the low to mid
20s on Tue and Wed night with highs on Wed in the mid to upper
30s as another area of high pressure settles over IL by sunset Wed.
A weather system moves into the upper Midwest and Great Lakes
region on Friday keeping its precipitation north of central IL
then. Highs in the lower 40s Thu moderate back to the upper 40s
and lower 50s on Friday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 558 AM CST Sat Nov 18 2017

12Z/6 am surface map shows 993 mb low pressure over central MO
with a frontal boundary extending ne along I-55 in central IL.
Numerous showers and scattered thunderstorms to continue this
morning over central IL as a strong cold front pushes se of DEC
and CMI around 15Z/9 am and to I-70 by 18Z/noon as low pressure
deepens to 989 mb over northeast IN. IFR to MVFR conditions to
occur into the afternoon with showers diminishing from nw to se
between 21-24Z. Breezy south winds gusting to 18-24 kts along I-72
early this morning will turn NW during mid/late morning and
increase to 18-23 kts with gusts in the 30s late morning into
early evening. MVFR clouds to scattered out during early/mid
evening as brisk nw winds gradually diminish to 10-15 kts and
gusts to around 20 kts overnight.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 9 PM CST this evening for ILZ040>057-061>063-
066>068-071>073.

&&

$$

SHORT TERM...07
LONG TERM...07
AVIATION...07


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