Area Forecast Discussion
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FXUS63 KILX 072306

606 PM CDT WED OCT 7 2015

.SHORT TERM...(Tonight)

Temperatures rebounding nicely this afternoon, with most areas of
the CWA in the mid-upper 70s at 2 pm. Main area of clouds the last
few hours has been a blob of stratocumulus across Missouri, spilling
a bit over the Mississippi River, although this eastern flank is
taking on more of a diurnal look with time.

Main concern for the forecast tonight remains with any fog
redevelopment. The area of concern continues to shrink, as the ridge
axis shifts east overnight and winds start to pick up ahead of the
shortwave currently advancing across the Dakotas. Currently thinking
that areas along and east of I-57 would be most prone, as the winds
there will remain very light with the ridge axis not too far away.
Lower levels of the forecast soundings suggest the fog would be
shallower than recent nights. Will only mention patchy fog late
tonight at this point. Otherwise, skies generally should be partly

.LONG TERM...(Thursday through Wednesday)

Main forecast concern will be timing of precip into the area along a
cold front slated to push through central Illinois tomorrow night
into Friday morning. Most of the operational models now similar in
their timing of the cold front across the forecast area Thursday
night with one more warm day ahead of the boundary as afternoon
temperatures top out mostly in the lower 80s with a gusty south to
southwest wind. We may even see a few mid 80s across west central
IL if cloud cover holds off during the day. Models suggest some
weak instability and lapse rates just ahead of the cold front late
Thursday afternoon with NAM forecast soundings a bit more
aggressive in forecasting Mixed Layer Capes of around 1000 J/KG
in a rather narrow axis stretching from southeast Iowa through
extreme west central Illinois, before the instability wanes with
the loss of daytime heating just after 00z. 0-6km shear values of
around 30 kts forecast across west central IL late tomorrow
afternoon and evening, so some storm organization may occur just
ahead of the cold front, but with most of the models indicating
the boundary still well out to our west/northwest tomorrow
afternoon, it appears that may occur over far eastern Iowa into
northwest Illinois. We may see some isolated storms produce gusty
winds and small hail, but with the weaker lapse rates depicted on
the latest models, it appears the hail threat has diminished. The
highest POPs will occur across the far northwest late tomorrow
afternoon with 50-60 POPs depicted along the frontal boundary
further south and east into central IL tomorrow evening, where the
low level convergence will be maximized.

Lingering shower chances will slide into southeast Illinois Friday
morning and gradually work off to the east and south of our forecast
area by late in the day. Much cooler weather will invade central
IL for a few days before a rapid warm up pushes in Sunday ahead
of a fast moving cold front which now looks to be pusing into our
forecast area Monday morning. With the fast movement of the
boundary and the better dynamics well to our north, not much of an
opportunity for moisture to work its way back into our area ahead
of the early week frontal passage so will continue to keep the
forecast dry ahead of this feature. Another quick shot of cool air
will push in behind the front later Monday into Tuesday, but a
fast turn-around in temps expected Tuesday night into Wednesday
ahead of another quick moving shortwave and frontal boundary
slated to push through our area dry for Wednesday afternoon and


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)

VFR conditions expected through much of the next 24 hours. As a
high pressure axis shifts eastward, light and variable winds will
become more south-southwest after 09Z and increase to near 10
knots Thursday morning. Currently thinking that any fog that forms
would be mainly from around KCMI south and eastward, and have kept
a TEMPO MVFR group at that site. After 18Z thursday...a cold front
will approach the area from the northwest...bringing increased
southwest winds of 10-15 kts gusting to around 20 well as
increasing chances for showers and thunderstorms. Have included
VCTS with continued VFR conditions after 21Z for KPIA-KBMI as
timing/location uncertainties of potential MVFR conditions with
thunderstorms preclude mention at this point.




SHORT TERM...Geelhart
AVIATION...Onton is the U.S. government's official web portal to all federal, state and local government web resources and services.