Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 231734

Area Forecast Discussion
National Weather Service Lincoln IL
1134 AM CST Mon Jan 23 2017

Issued at 1050 AM CST Mon Jan 23 2017

A narrow ridge of high pressure is building into the Plains and
the Missouri River Valley, but trapped low level moisture is
keeping a thick layer of clouds over Central Illinois and likely
to continue through tonight. North/northwesterly winds also to
continue through the day, eventually becoming lighter as the ridge
shifts eastward. Forecast is doing well and updates are not
anticipated at this time.


.SHORT TERM...(Today and tonight)
ISSUED AT 329 AM CST Mon Jan 23 2017

Main feature through Monday night will be the extensive stratus
deck over the upper Midwest that will continue to advect over
central and southeast Illinois bringing cloudy conditions. Perhaps
some thinning of the cloud layer in the afternoon as surface
temperatures max out in the low to mid 40s, but at this point looks
to remain cloudy. Lows tonight generally around 32 degrees, with
cooling limited by cloud cover and lingering low level moisture.

The cloudy conditions will limit fog development so overnight fog
should generally be thin. However, a frontogenetical zone around 850
mb looks to continue eastward across the state coupled with an upper
level shortwave and will bring isolated light showers through early
morning today. Currently the broken band of showers is just west of

Breezy NW winds 10-20 mph will continue much of the day today due to
the influence of the deep low pressure system over the southeast.
Winds to lighten overnight tonight as the low continues
northeastward and pressure gradients weaken over central IL.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 329 AM CST Mon Jan 23 2017

00Z forecast models continue to build an upper level ridge into IL
by sunrise Tue and shifting east into the Ohio river valley by Tue
afternoon. This should keep most of the CWA dry during the day Tue.
Just have a slight chance of light rain showers over Knox and Stark
counties Tuesday afternoon, mainly late. An upper level trof near
the West Coast, will shift east into the Rockies by Tue morning and
develop surface low pressure over eastern CO and into nw KS. Surface
low pressure tracks toward the IA/MO/NE border by sunset Tue.
Meanwhile weak surface high pressure ridge over IL at sunrise Tue
shifts east into the Ohio river valley Tue afternoon with increase
SSE winds during day Tue bringing milder highs in the upper 40s,
with lower 50s sw CWA. A mostly cloudy day overall for central IL
Tue with more sunshine possible in southeast IL especially south of

Low pressure to track into central IA by midnight Tue night, into
south central WI by sunrise Wed and then toward northern lower MI
and Lake Huron by sunset Wed. Continued 20-40% chances of light rain
showers over northern CWA especially from I-74 on Tue night and Wed
while southeast IL remains dry. Lows Tue night in the upper 30s
central IL and lower 40s southeast IL, with mid 30s by Galesburg.
Highs Wed range from lower 40s over the IL river valley, to lower
50s near Lawrenceville in far southeast IL. Upper level trof digs
into central IL Wed afternoon and Wed night bringing in cooler air.
This to turn light rain chances to light snow chances from nw to se
during Wed night but little or no snow accumulations. Lingered small
chances of light snow or flurries over ne CWA Thu, mainly in the

A major upper level pattern shift will occur Wednesday night and
Thursday across the Midwest, bringing more seasonable winter weather
to the region. A strong upper level low lifts into southeast Canada,
while upper ridging builds over the west coast. A few northern
stream shortwaves will track southeast out of central Canada, and
dig a broad upper level trough over the eastern United States.
These weak shortwave may produce a few flurries Wed night and Thu,
but no accumulations expected over central IL. Temperatures will
cool closer to normal for late January. Highs Thu in the mid to
upper 30s, with lower 30s by Galesburg. Highs in the low to mid 30s
from Friday through Sunday, then back in the mid to upper 30s next
Monday. Lows Thu night in the mid 20s, with lower 20s by Galesburg.
Lows 20-25F from Fri night thru Sunday night.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1130 AM CST Mon Jan 23 2017

Weak ridging to the west and north/northwesterly winds getting
lighter this evening as the ridge passes. Today, cigs on the cusp
of IFR/MVFR around 1000ft. Expect cigs to lift somewhat with the
heat of afternoon...before coming back down tonight. Models
producing some weak reduced vis for btwn 09Z and 14Z...and have
reflected the trend in the TAFS, in the IFR range.




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