249 
fxus63 kilx 151955 
afdilx 


Area forecast discussion 
National Weather Service Lincoln Illinois 
255 PM CDT Wednesday Oct 15 2008 


Discussion... 
issued 255 PM CDT Wednesday Oct 15 2008 


Latest surface analysis had low pressure centered over northern 
Ontario...with the trailing cold front extending southwest across 
central Illinois...and into the Southern Plains. Showers and a few 
thunderstorms persist along and just behind the front. Not many 
forecast concerns the next few days aside from temperatures once 
the front and the associated precipitation departs tonight and 
high pressure largely dominates our weather pattern. 


12z models in reasonable agreement over the next few days...though 
there are discrepancies in the strength of the upper wave that moves 
through the region on Friday. Most model solutions...even those with 
a stronger upper wave...have no surface reflection with Friday/S 
wave. For this reason...and the relatively dry airmass that will be 
in place...will keep the forecast dry. 


Short term...tonight through Saturday... 


Tonight...cold front...lingering showers...and cloud cover...will 
make steady progress south and east tonight. Current trends suggest 
precipitation will clear forecast area by shortly after midnight. 


Thursday through Saturday...quiet but cooler weather than seen in 
recent days is expected through the period. High pressure is 
expected to be in control at the surface...with largely neutral 
flow...except for Friday/S wave...expected aloft. Friday/S wave will 
bring in a reinforcing shot of cold air behind today/S front...with 
850 mb temperatures around zero. If skies clear rapidly enough and 
winds die off quickly enough once the wave departs...Saturday 
morning will likely be the coolest one we have seen in a while. 
Frost is certainly possible...but not definite...and its threat will 
need to be monitored. 


Long term...Saturday night through Wednesday...models/ensembles 
generally agree that quiet weather will persist. Again...high 
pressure will be in place at the surface for the majority of the 
time...with neutral flow aloft. Another wave in the northern stream 
may impact the region by Monday...but the better forcing should stay 
to our north. For this reason...will not go above a slight chance of 
showers in the forecast at this time. Heights will be on a slow 
rise...except possibly on Monday...through the period...so 
temperatures should gradually moderate. 


Bak 
&& 


Aviation... 
issued 1239 PM CDT Wednesday Oct 15 2008 


Low pressure tracking through the Illinois River valley will drag 
a cold front across central Illinois this afternoon. Kpia is 
already on the back-side of this system...with winds out of the 
north and ceilings below 1000ft. Further east...winds are from the 
southwest and ceilings get progressively higher. Main band of rain 
associated with the approaching cold front is now just east of 
I-55 and will impact both kdec and kcmi over the next one to two 
hours. After that...rainfall will be much more scattered in nature 
and will be handled with a tempo group at all taf sites. Any 
lingering showers will come to an end early this evening...followed 
by a clearing trend overnight. Based on model relative humidity profiles and 
latest satellite observation...it appears skies will clear at kpia around 
06z...then further east at kcmi by around 09z. 


Barnes 
&& 


Ilx watches/warnings/advisories... 
none. 
&& 


$$