Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 181720
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1220 PM CDT Wed Apr 18 2018

.UPDATE...
Issued at 1050 AM CDT Wed Apr 18 2018

Have decided to issue a Wind Advisory for the southeast CWA,
basically south of I-70, for this afternoon and early evening.
Winds expected to ramp up once the low passes. Bufkit momentum
transfer is showing 30-40 knots mixing down to the surface, in
areas where skies are currently sunny. May see some stronger gusts
over 35 mph between I-72 and I-70, but more of a cloud cover in
that area should temper the highest gusts.

UPDATE Issued at 947 AM CDT Wed Apr 18 2018

Satellite imagery showing upper low moving into central Iowa,
while the surface low was centered near Quincy. So far, the
associated mixed precipitation has stayed to our north, though a
narrow band of showers had started moving into Knox and Fulton
Counties. RAP/HRRR has a good handle on this so far, and expands
the rain showers across the northern CWA north of the low track.
Top-down method suggests some rain/snow mix this afternoon over
the extreme northern CWA, which more of an expansion south to
I-74 early this evening.

Quite a large temperature range over the CWA today, which mainly
upper 30s/near 40 northwest, to near 70 far southeast.
Temperatures should begin steadily falling this afternoon after
the low passes.

Updated zones/grids sent for the latest precip/temperature trends.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 345 AM CDT Wed Apr 18 2018

09Z/3 am surface map shows 998 mb low pressure over northeast
Kansas with a warm front over southern MO and near the KY/TN
border. A surface trof extends north of this low pressure over
western IA/MN. An area of showers was over western IA into
northeast NE and se SD with a cluster of thunderstorms over west
central IA. Temps ranged from lower 30s along and ne of I-74, to
the lower 40s south of I-70. Some broken mid level clouds of 7-8k
ft have spread across ne half of CWA from Macomb to Lincoln to
Terre Haute ne early this morning while still mostly clear skies
sw CWA. Aloft a 550 dm 500 mb low was along the central NE/SD
border with the convection east of this feature.

00Z models have continued to trend further south with surface low
moving from ne KS into track east and pass along or just north of
I-70 in southeast IL by 18Z/1 pm today, and into west central Ohio
by sunset. Showers appear to be confined to areas north of low
pressure track and also slower to arrive during this morning.
Continued mention of isolated thunderstorms from mid morning into
midday over areas north of I-74. Large temp gradient today, with
highs ranging from upper 30s to lower 40s from Peoria north to the
mid to upper 60s in southeast IL with Lawrenceville approaching
70F where windy conditions to develop in warm sector with gusts of
30-40 mph this afternoon. Colder air arriving on back side of
system to turn light rain showers to light snow showers over far
northern CWA during mid/late afternoon and over ne half of CWA
during this evening. Minor snow accumulations of less than a half
inch possible ne of I-74 this evening. Have isolated light snow
showers lingering from Bloomington and Champaign ne early
overnight. Lows tonight in the lower 30s central IL (Galesburg
near 29F) with mid to upper 30s in southeast IL.

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 345 AM CDT Wed Apr 18 2018

A cool day in store on Thu with highs of 50-55F, coolest from I-74
ne as upper level trof shifts into the eastern states and 1034 mb
high pressure settles into northern IA by sunset Thu. Clouds to
start the day Thu, then decreasing clouds from nw to se during the
day Thu. NNW winds 10-15 mph and few gusts up to 20 mph especially
in eastern IL to make it feel cooler. High pressure to ridge into
IL late Thu night into Friday. This will bring fair skies Thu
night and Fri, with cool lows in the lower 30s, with some upper
20s northern CWA. Southeast IL will likely need another freeze
warning overnight Thu night. Highs Fri modify to 55-60F with
lighter winds. These readings are still near 10F below normal.

Extended models have cutoff upper level low off the west coast
moving into the 4 corners/southern Rockies by 18Z/Fri and into SE
CO and TX panhandle by 18Z/Sat. This cutoff system then tracks
into the mid to southern MS river valley by Sunday afternoon, and
then into the southern TN river valley Monday. Brunt of models
continue to keep its moisture south of our CWA through Monday,
though ECMWF now brings some qpf into southeast IL by Monday
afternoon. Followed consensus of models which keeps our area dry
through Tuesday. Temps start out below normal this weekend with
highs in the upper 50s/lower 60s Sat and lower 60s Sunday. Temps
then modify to mid to upper 60s Mon and upper 60s on Tue. A
frontal boundary pushing se into IL Tue night to bring next chance
of rain showers which could linger into Wed with a bit cooler
highs in the lower 60s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1218 PM CDT Wed Apr 18 2018

Surface low currently passing just south of KDEC, and MVFR
ceilings are spreading across central Illinois behind it.
Precipitation so far has been well to the north, but some periodic
rain/snow showers are expected from KPIA to KCMI later this
afternoon into the evening. This area is most likely to see any
IFR conditions from evening through overnight, but overall low
MVFR ceilings will prevail in central Illinois. Winds will quickly
shift around to the northwest this afternoon behind the low, with
some gusts up to 30-35 knots possible near KSPI/KDEC. Gusty winds
should continue through the night, before slowly diminishing along
with the clouds on Thursday morning.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 7 PM CDT this evening for ILZ066>068-071>073.

&&

$$

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


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