Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 231127

Area Forecast Discussion
National Weather Service Lincoln IL
627 AM CDT FRI SEP 23 2016

.SHORT TERM...(Today and tonight)
ISSUED AT 342 AM CDT Fri Sep 23 2016

The surface boundary sitting across northern Illinois this morning
will slowly sag south into the central/southern part of the state.
One would think that showers and storms will develop along this
boundary later this afternoon after max heating of the day. However,
the mid level ridge will be sitting right over the top of the area
and this subsistence should squash any possible convection. So
convection that is ongoing in Iowa will likely remain only in
northern IL today, resulting in a dry forecast for the ILX CWA for
today and into tonight. Any cloud cover will come from the blow-off
from the storms in Iowa. Winds are light now, but should become
southerly again this afternoon, keeping well above normal temps in
the area for another day. Highs should be in the mid 80s in the
north to around 90 in the south, this afternoon. Lows should be in
the middle 60s for tonight.

.LONG TERM...(Saturday through Thursday)
ISSUED AT 342 AM CDT Fri Sep 23 2016

Model performance has been disappointing for the late weekend
system.  The NAM has joined the party at this point, and is in
agreement with the GFS for a new and more progressive approach,
resulting in pops showing up in the forecast for Sunday. Models are
having a major problem with handling this system and pattern shift,
and the ECMWF is the closest to consistent that there is...and
remains slower with the overall upper trof.  All of the models are
splitting the trof/energy and leaving a small closed low over the
SW, resulting in a bit of a breaking up of the dynamics as the
system moves through the Midwest.  With the GFS, the upper low is
deeper, stronger, and further south.  The ECMWF is further north as
a weaker open wave.  The nature and intensity of the sensible
weather at the surface is the question mark...scattered showers vs a
more cohesive line of potential thunder. Rain is the forecast, but
the chances are low at this point, if only for timing and coverage.
This is late Day 3 and into Day 5, Sun night into Tuesday.
Confidence is low presently, but subsequent runs may end up showing
a little more continuity if the trend continues.  Until then, an
unseasonably warm weekend expected.  With the system and front later
in the weekend...the rain chances return, with much cooler temps as
highs on Monday/Tuesday only expected into the 70s.  The cool air is
short-lived however, and the warming trend returns to the latter
half of the week as the mid level ridge shifts into the Midwest yet


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 627 AM CDT Fri Sep 23 2016

VFR conditions will prevail at all sites next 24hrs. Two sites,
PIA and CMI, based on temp/dewpt spread seems to indicate that
some light fog is possible. So have included TEMPO group for each
site for next couple of hours, for 3-4sm. Mid and high clouds is
all expected next 24hrs given the cloud blow-off coming over the
sites from the northwest. Winds will be light and variable.


.ILX Watches/Warnings/Advisories...


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