517 
FXUS63 KILX 162312
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
612 PM CDT Wed Oct 16 2019

.SYNOPSIS...
Issued at 258 PM CDT Wed Oct 16 2019

Brisk northwest winds over central and southeast Illinois will
taper off this evening. Clouds will gradually clear out overnight
as well. High pressure will provide dry and warming conditions 
Thursday through Friday. The next chance of showers and isolated 
thunderstorms will arrive overnight Friday night over the IL river
valley, and across the area on Saturday as a weak front moves in.

&&

.SHORT TERM...(This evening through Thursday)
ISSUED AT 258 PM CDT Wed Oct 16 2019

Deep low pressure centered over Lake Huron will continue to
influence our weather through tonight. As a result of the deep
occluding low, strong northwest winds have become established 
through a deep layer of the atmosphere. That has transferred into
our gusty conditions, which we expect to continue into evening 
before subsiding. Another result of the low will be persistent
cloud cover at least through midnight. A few pockets of clearing
will be seen, but clouds will dominate the skies through this
evening before clearing later tonight. A few of the CAMs are
showing a few showers even developing in the Champaign to Danville
areas later tonight. Most are dry, so will not introduce precip
tonight. But an enhanced area of forcing looks to rotate through
the northeast portion of our CWA later tonight. That will keep
clouds longer overnight in that area. 

Depending on clearing, we could see patchy frost develop tonight,
as lows dip into the mid 30s in a few locations. 

Thursday is expected to see clearing skies, if any clouds linger,
and slightly warmer conditions. The surface ridge axis is expected
to pass from west to east across Illinois on Thursday, which will
trigger a wind shift to SW winds by later in the afternoon. 

.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 258 PM CDT Wed Oct 16 2019

More patchy frost can not be ruled out Thursday night along the
Indiana border, but chances are lower due to winds becoming
southerly already by Thursday evening. Lows in western counties
will be in the lower 40s, but cooler mid to upper 30s are forecast
in the east from Danville to Lawrenceville.

Dry conditions will continue on Friday, before the next weather
system approaches from the Plains Friday night. Increasing
southerly flow and low level dewpoints will aid in the development
of showers from late Friday night through Saturday afternoon. The
system will be progressive, with steady eastward progression on
Saturday. The speed of the system will limit the time for moisture
return, but we do expect a line of showers and isolated storms to
develop in the marginally unstable airmass, especially Saturday
afternoon. Dry conditions should return for Saturday night, with
only a minor temperature adjustment behind the cold front due to
zonal flow aloft continuing. 

A warming trend will continue Sunday night into Monday as a
vigorous low pressure system takes shape in the Plains. showers
and scattered storms are expected to develop ahead of this dynamic
low, which will be centered somewhere from western Iowa to
southern Minnesota by 12z/7am Monday. The GFS is about 6-12 hours
faster than the ECMWF with a band of strong convection and locally
heavy rainfall. The GFS window of precip is targeting Midnight to
Noon on Monday, whereas the ECMWF is targeting 6 am to 8 pm on
Monday. A more robust moisture feed will develop into this system,
with an open Gulf flow becoming established. The precipitable
water values are expected to climb into the 1.50-1.75" range on
Monday, which is above the 90th percentile for this time of year.
The heaviest rainfall totals look to be south of I-72 and
especially S of I-70, where 1.5-2" of rainfall could occur with
this system. 

Despite the frontal passage on Monday, we are seeing a lobe of
energy and wrap-around moisture surging southward into Illinois on
Tuesday, per the ECMWF and Canadian-NH. So spotty showers may
persist on Tuesday. Cooler high pressure will arrive for 
Wednesday, as the deep low lifts into eastern Canada.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 612 PM CDT Wed Oct 16 2019

VFR conditions are expected for the next 24 hours. A high pressure
ridge axis approaching the area will bring decreasing cloud cover
and winds. Initial broken cloud cover at 4000-4500 feet over the 
area will slowly dissipate and shift eastward overnight, with few
clouds re-developing Thursday afternoon. Winds NW 8-12 kts this
evening will slowly decrease overnight, becoming light and
variable to NW 5-10 kts by Thursday afternoon.

&&

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

&&

$$

SYNOPSIS...Shimon
SHORT TERM...Shimon
LONG TERM...Shimon
AVIATION...37