Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 271749

Area Forecast Discussion
National Weather Service Lincoln IL
1249 PM CDT THU OCT 27 2016

Issued at 1044 AM CDT Thu Oct 27 2016

Cold air advection across the well as persistent cloud
cover through most of the day will keep the temperatures rather
cool. High temperatures in Central Illinois will be mostly in the
50 with north/northwesterly winds becoming lighter towards the
evening hours as the sfc ridge axis moves closer to the region and
lessen the pressure gradient. No updates anticipated at this time.


.SHORT TERM...(Today and tonight)
ISSUED AT 330 AM CDT Thu Oct 27 2016

The cold front that brought the showers/storms to central and
southeast Illinois in the past 24 hours has just about exited our
far southeast counties. Cyclonic flow and low level cold advection
is expected to persist across the region for much of the day, but a
progressive ridge of high pressure will shift across the region late
today into tonight. Due to the strength/persistence of the cold
advection and extent of low clouds expected for much of the day,
have cooled forecast highs into the 50s areawide. Clearing should
finally occur late in the day as the high pressure builds in. This
late clearing and recent rains may pose a fog threat by late
tonight. A strong signal for fog does not exist in the current
guidance, so have left it out at this time. This threat will be need
to be monitored closely by later shifts.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 330 AM CDT Thu Oct 27 2016

Some patchy fog may occur early Friday morning in southeast IL
mainly south of our CWA, otherwise a mostly sunny and nice fall day
in store with increasing southerly breezes bringing milder
temperatures. Highs Friday should reach 70-75F with warmest readings
over west central IL. Friday night will only see lows in the upper
50s to around 60F with mildest readings west of I-57. This is about
20 degrees above normal for late October.

Even warmer highs on Saturday in the mid to upper 70s and our sw CWA
will be approaching 80F with breezy sw winds as clouds increase over
northern CWA with approaching cold front from the Great Lakes as
surface low pressure moves east across the northern Great Lakes into
southeast part of Ontario and southern Quebec. 00Z models have
trended a bit slower with cold front going southward across the
southern Great Lakes and into central IL late Saturday night. Shower
chances still appears to get about as far south as I-74 by overnight
Saturday night from frontogenetic and low level jet forcing with
isolated elevated thunderstorms over northern IL just north of our
CWA (see SPC day3 outlook). Lows Sat night of 52-58F. Skies become
partly to mostly sunny on Sunday with highs ranging from mid 60s
northern CWA to near 75F along highway 50 from Flora to

Upper level ridge over the MS river valley Sunday night shifts east
into the Ohio River valley on Monday while low pressure moves to
near the MN and eastern Dakotas border by sunset Monday. Monday
looks like a repeat of Saturday`s weather with warm highs back in
the mid to upper 70s (near 80F SW CWA) with breezy southerly winds.
Models are slower with this low pressure and associated cool front
as well and have gone a bit warmer on Tue with highs 68-76F, warmest
in southeast IL. Dry conditions looks to continue through Tue
evening. Then the frontal boundary to push into nw IL during mid
week and bring chances of showers and isolated thunderstorms to
mainly areas north of I-70 from overnight Tue night into Thu
morning, then into southeast IL as well by Thu afternoon and Thu
night as front pushes further south with surface low pressure
ejecting northeast along front to near IL. Temps to gradually cool
from nw to se during Wed/Thu with highs by Thu in the lower 60s over
IL river valley and upper 60s in southeast IL, so still above


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1246 PM CDT Thu Oct 27 2016

MVFR conditions still dominate Central Illinois terminals, and
will for a couple hours until the stratus slowly disintegrates
across the region. Satellite imagery looks favorable to an early
evening breaking out of the cloud cover. However, persistent
clouds have kept the mixing to a minimum, and a shallow layer of
higher RH at the ground may result in some patchy fog overnight.
Have kept it conservative, and the vis will be the major concern
through the overnight as winds lighten under the ridge and the
skies clear, creating a radiational fog set up.


.ILX Watches/Warnings/Advisories...


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