Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 231139
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
639 AM CDT Mon Apr 23 2018

.SHORT TERM...(Today and tonight)
ISSUED AT 321 AM CDT Mon Apr 23 2018

Northeasterly winds continue today and most of tonight for
Central Illinois as a low stalls just to the south at the
confluence of the Ohio River. That low aloft is cut off and making
very slow forward motion, if any. Overnight, it has shown some
signs of brief retrograde. At any rate, the slow motion will
likely keep some cloudiness over the southern half of the state at
the very least. Some precip finally working its way into
southeastern IL up to Interstate 70, having had plenty of lower
level dry air to saturate. Spreading of the precip to the north is
expected through the day, though the northern extent is the bigger
question. NW of the Illinois River Valley is least likely to see
the precip, and as a result will have the higher max temps in the
upper 60s. Further to the south with the cloud cover and precip,
high temps will be confined to the low 60s. Temps only dropping
into the upper 40s overnight as that low makes very slow progress
and keeps the clouds in place with some showers through the
overnight.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 321 AM CDT Mon Apr 23 2018
Extended forecast remains largely unchanged. Slight precip
chances mainly in the east continuing through tomorrow with the
slow progress of the upper low into the Appalachians. Forecast
dries out as the GFS comes around to a more ECMWF/NAM solution
with the evolution of the kicker/next system. Previously phasing
the two shorter waves moving into the Plains/Midwest midweek...the
GFS et al are now keeping the two smaller waves separate,
resulting in a drier forecast through the middle of the week.
First pushes through the Great Lakes mid week, although its effect
as a kicker is a little less than, and the current low remains cut
off and a bit wobbly over the mid eastern seaboard. Another wave
dives into the southeast, bringing a wet end of the week to the
Gulf states. Illinois ends up between them and mid week stays dry.
However, that second wave sets up a more northwesterly flow aloft,
and the next trof is a bit more pronounced and brings a shot of
cooler air into the region. Showers move in with the frontal
boundary Thursday night into Friday as the surface low starts to
develop just to the south. Weekend looking dry and warmer on the
other side of precip for Friday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 639 AM CDT Mon Apr 23 2018

VFR conditions expected to deteriorate today into tonight as
showers associated with a slow moving low pressure system to the
south spread northward, along with lowering ceilings. Terminals
along I-72: KSPI-KDEC-KCMI should see the earliest shower activity
and MVFR cigs, currently timed around 18-20Z. Farther to the
northwest at KPIA, showers are doubtful, while MVFR cigs will
likely hold off until this evening. Overnight, guidance points to
a continued lowering of ceilings, potentially reaching IFR. At
this time, best chances of this look to be at KCMI and have not
included elsewhere due to lower probabilities. Winds E-NE 10-15
kts with higher gusts to around 20 kts by afternoon, diminishing
to around 10 kts or less after 00Z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SHORT TERM...HJS
LONG TERM...HJS
AVIATION...37



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