393 
fxus63 kilx 072325 
afdilx 


Area forecast discussion 
National Weather Service Lincoln Illinois 
625 PM CDT Thursday Aug 7 2008 


Discussion... 
issued 228 PM CDT Thursday Aug 7 2008 


Models continue to lack model to model and run to run consistency 
though 12z suite seems to be better than 00z NCEP suite. 


Short term...tonight through Sunday... 
high pressure continues to dominate the Midwest as drier air 
filters into Illinois. Convection has moved well south of the 
state. Cool and dry are the buzzwords into the weekend. Some 
patchy fog near agriculturally active areas may be possible tonight 
with light winds and clear skies...but as dew points drop into the 
50s any coverage will be small. 


12z GFS and NAM are coming more in line with 00z European model (ecmwf) on the 
evolution of the highly meridional pattern expected into next week. 
Both NAM and GFS move a reinforcing shot of cooler air into 
Illinois on Saturday night and Sunday...but moisture should be quite 
limited with the effective front over the lower Mississippi Valley 
and the Gulf cut off. Only NAM is painting any precipitation. Will go with 
drier GFS and European model (ecmwf) in holding off chances of precipitation through the 
weekend. 


Long term...Sunday night through Thursday... 
European model (ecmwf) and GFS diverge significantly into early next week as GFS 
cuts off an upper low over the Great Lakes and the European model (ecmwf) persists 
with broad trough over eastern North America. The GFS would suggest that 
the upper low in the area should allow for cooler temperatures and at 
least chance probability of precipitation beginning Monday night into midweek. The European model (ecmwf) 
solution implies slightly warmer and drier conditions as bulk of 
middle-level energy remains over Great Lakes. 


Will follow HPC guidance which went with the Canadian Gem as a 
compromise. This suggests introducing probability of precipitation on Tuesday and Tuesday 
night. However...uncertainty is above average with this scenario. 
As for temperatures...slightly below normal readings should persist with 
generally northwest flow throughout the depth of the atmosphere 
indicated by European model (ecmwf)...GFS...and Gem. 


&& 


Aviation... 
issued 620 PM CDT Thursday Aug 7 2008 


Except for a few hours just before sunrise Friday morning...VFR 
conditions are expected through the period. Diurnal cumulus field quickly 
dissipating early this evening and that trend should continue with 
mostly clear skies expected overnight. Any fog development tonight will 
be patchy at best as once again good mixing occurred today with 
dew points lowering into the upper 50s to lower 60s at peak heating 
time. Surface winds will be light northerly tonight and continue out of the north 
on Friday at speeds of 10 kts or less. 


Smith 
&& 


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


$$