Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 260425
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1125 PM CDT MON JUL 25 2016

.UPDATE...
Issued at 825 PM CDT Mon Jul 25 2016

The actual cool front has slippped south of our forecast area this
evening, however, a couple of weak mesoscale boundaries were
noted on the ILX radar late this afternoon. May have been a dew
point discontinuity of just a suttle wind shift that produced just
enough convergence/stretching of the updraft to produce some
funnel clouds. The ones reported to our office were in Champaign
county, especially along the Interstate 74 corridor.

With the frontal boundary over far southern Illinois, the better
chances for scattered showers and thunderstorms will be across
far southeast Illinois tonight as a weak upper level wave and
attendant surface low shifts east along the boundary. Will
continue to carry low change POPs mainly along the I-70 corridor
overnight but will need to watch this as short term forecast
models continue to edge precip further north later tonight as the
surface wave moves along the stalled frontal boundary to our
south.

Further north, some patch fog will develop overnight due to the
combination of a mostly clear sky, light wind and copious amounts
of low level moisture from previous days rainfall. Have made only
minor changes to the weather/precip grids for the overnight hours
with the remainder of the forecast in good shape. Should have the
update out by 845 pm.

&&

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 258 PM CDT Mon Jul 25 2016

Despite cold front dropping southward toward the Ohio River Valley,
the airmass remains quite moist across central Illinois this
afternoon, with 18z/1pm surface dewpoints generally in the lower to
middle 70s.  The significantly drier air lags well behind the front
across Iowa and far northern Illinois where dewpoints have mixed
into the lower to middle 60s.  Mid/high clouds currently blanketing
the area will gradually push E/SE and should be largely confined to
locations along and south of the I-70 corridor tonight.  12z Jul 25
models all show scattered showers and thunderstorms across the SE
KILX CWA this afternoon and tonight, while areas further north
gradually clear out.  Have maintained low chance PoPs along/south of
I-70 through tonight accordingly.  Elsewhere around the area, have
gone with a dry forecast with patchy fog developing overnight.

High pressure will build into the Great Lakes on Tuesday, providing
mostly sunny and dry weather across most of the area.  The exception
will be south of I-70, where a few showers and thunderstorms will
remain a possibility in closer proximity to the stalled frontal
boundary near the Ohio River.  High temperatures will reach the
middle to upper 80s.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 258 PM CDT Mon Jul 25 2016

High pressure will slowly drift east of the area Tuesday night and
allow the frontal system to begin to lift back north and become
oriented northwest to southeast across MO and into southern IL. As
the high pressure continues to move east the front out west will
slowly get closer to the CWA and bring the return of showers and
thunderstorms to the southwest third of the state beginning Wed.
Then more showers and storms will advect northward as the front
lifts further north and then cover the entire CWA Wed night and
Thur. As the associated mid level trough rotates through the area,
somewhat cyclonic flow/northwest flow will setup. This will keep the
sfc boundary near the area through the rest of the week, which will
keep chance of showers and thunderstorms over the CWA through the
rest of the week and into the weekend. Things should improve some
the latter part of the weekend as the chance of showers and
thunderstorms will be limited to the east and southeastern parts of
the CWA.

High pressure will also bring cooler temps for Wed and Thur. And
with cyclonic/northwest flow setting up over the area, slightly
cooler temps will prevail the remainder of the week and into the
weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1120 PM CDT Mon Jul 25 2016

High pressure will slowly build into the region over the next 12
to 18 hours bringing in slightly drier air and mostly VFR
conditions. The only exception will be in the 08z-13z time frame
where some MVFR vsbys in fog will be possible. Forecast soundings
suggest it will be quite shallow so any fog the does form
overnight will quickly dissipate btwn 13z-14z. Scattered to broken
cumulus will develop by late morning into the afternoon hours with
cig bases in the 4000-5000 foot range. With the slightly drier
look to the forecast soundings tomorrow, will lean more towards
scattered clouds at this time. Light and variable winds tonight
will become light northeast to east on Tuesday with speeds of
less than 10 kts.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...Smith
SHORT TERM...Barnes
LONG TERM...Auten
AVIATION...Smith



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