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Area forecast discussion 
National Weather Service Lincoln Illinois
239 PM CDT Sat Oct 25 2014

Short term...(tonight)
issued at 223 PM CDT Sat Oct 25 2014

Weak frontal boundary continues to settle southward toward the Ohio
River this afternoon, allowing a drier airmass to trickle in from
the northwest. 18z/1pm dewpoints across Iowa are only in the middle
to upper 30s, and this airmass will arrive across central Illinois
tonight. Upstream satellite imagery and forecast soundings indicate
clear skies beneath building high pressure tonight, resulting in
excellent radiational cooling. Have therefore undercut mav guidance
by a couple of degrees, with lows dipping into the lower to middle


Long term...(sunday through saturday)
issued at 230 PM CDT Sat Oct 25 2014

Very pleasant weather expected through Monday and then a deep trof
and associated frontal system will affect the area late Monday into
Tuesday bringing shower chances to the region. Some very chilly air
poised to our north by the end of the week which may bring our first
widespread freeze of the season to parts of central and east central
Illinois next weekend.

High pressure will settle into the area for Sunday bringing in slightly
cooler temperatures, especially to the north and east where afternoon
readings will approach 70, while further south and west the Mercury
will rise into the middle 70s. A warm front is slated to push northeast
across the area Sunday evening with the better lift and elevated
instability forecast to be across the lower Great Lakes, so will continue
to keep rain chances out of the grids with an increasing southerly wind
helping to keep overnight lows quite mild for the end of October. Most
of the operational models agree with the faster solution with respect
to the frontal timing across our area on Tuesday. With the more progressive
trend to the system, deeper moisture will not have a chance to get this
far north ahead of the front late Monday night into Tuesday, however,
still enough mid and upper level forcing associated with the deep 500
mb trof to set off some showers with most unstable CAPES of up to 500
j/kg just ahead of the front, so will continue to hold on to some isolated
convection Monday night into Tuesday morning. Models sweep the front
to our east by early afternoon with an impressive mid level dry slot
surging across central Illinois Tuesday afternoon taking the precip
and cloud cover well to our east.

Fairly cool 850 mb temperatures seen on models in the wake of
tuesday's system, so after the unseasonably warm temperatures
tomorrow and Monday, we should see temps closer to or even below
normal by Wednesday afternoon. The next weather system will track
southeast out of the northern plains on Thursday with little in
the way of moisture available with it to produce much in the way
of rainfall in our area. Low chance pops will be just to our west
late Wednesday night with slight chances for our area on Thursday
as the weak clipper like system shifts across central Illinois
during the day. The shortwave will effectively deepen in the
longwave trof over the Great Lakes which will usher in some of the
coolest air of the fall season so far later Friday and Saturday.
Very good model agreement with respect to 850 temp forecasts for
the end of the week with both the operational GFS and latest European model (ecmwf)
indicating -6 to -10 degrees c by late Friday into Saturday, which
will translate to highs struggling to get out of the 40s across
the north and east on Friday and Saturday with early morning lows
of 30 ot 35 degrees, with a few of our "colder" locations possibly
dipping into the upper 20s Saturday morning.


Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 1222 PM CDT Sat Oct 25 2014

VFR conditions will prevail through the entire 18z taf period as
high pressure builds into the region. Winds will initially be from
the northwest at 5 to 10kt this afternoon, then will become light/variable
tonight into Sunday morning. As the high begins to shift off to
the east, winds will become east/southeast toward midday Sunday.


Ilx watches/warnings/advisories...


Short term...Barnes
long term...Smith

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