Weather

473 
fxus63 kilx 071749 
afdilx 


Area forecast discussion 
National Weather Service Lincoln Illinois 
1249 PM CDT sun Sep 7 2008 


Discussion... 
issued 958 am CDT sun Sep 7 2008 


Middle-level short-wave responsible for the light rain last night has 
now tracked well to the east of the area across the eastern Great 
Lakes into Indiana. Subsidence in the wake of this feature has 
allowed skies to become mostly sunny across the northern kilx 
County Warning Area...with partly to mostly cloudy skies persisting along and 
south of I-72. Atmosphere remains unchanged from yesterday...so 
should see a good amount of diurnal cumulus developing later this 
morning into the afternoon...and the cumulus-rule verifies this quite 
nicely. Already beginning to see the first signs of the cumulus now 
forming on satellite imagery...so think balance of the day will be 
partly sunny across central and southeast Illinois. Current temperatures 
have risen into the lower to middle 60s...and are on track to 
reach forecast highs in the middle to upper 70s this afternoon. 
Have updated the grids to remove morning probability of precipitation and to better 
reflect latest sky cover trends. 






&& 


Aviation... 
issued 1249 PM CDT sun Sep 7 2008 


Scattered-broken cumulus with bases between 3000 and 4000ft has developed across 
central Illinois early this afternoon. This cloud cover will 
quickly dissipate toward sunset...but will be replaced by increasing 
middle-level cloudiness ahead of the next approaching weather system. 
12z models suggesting the bulk of the energy with this feature may 
remain west and north of the taf sites until Monday afternoon and 
evening. At this point...will gradually lower ceilings overnight 
and will introduce vcsh at kpia after 09z. With middle-level wave 
approaching from the west...will carry tempo group for -shra at 
kpia after 15z...but will only mention vcsh further east at kbmi 
and kspi. 


Barnes 
&& 


Previous discussion... 
issued 335 am CDT sun Sep 7 2008 


00z short range models have trended quicker with first middle level 
short wave trough exiting central Illinois early this morning. Models have 
trended further north with second stronger middle level short wave 
trough Monday/Monday night and heaviest rain appears to be over northern 
Illinois Monday. Models trending drier and warmer over southeast Illinois Monday. Models 
continue to show stronger high pressure building into the Midwest 
and Great Lakes Tuesday/Tuesday night clearing skies and dry weather. Extended 
models trending slower with next weather system later in the week and 
most models keeping Illinois drier and warmer Wednesday and Thursday as upper level 
ridge over the southeast states raises heights over central/southeast Illinois. 


Short term...today through Monday night. 


Initial middle level short wave trough moving east toward Illinois bringing 
widespread showers to central Illinois early this morning. Showers have 
ended north of peroia and moving into far southeast Illinois. RUC model was way 
too dry but NAM models appears to have a good handle on this 
precipitation which ends it by 15z/10 am. So have 20 to 30% chance 
of showers into middle morning from Peoria south. Very little 
lightning strikes past few hours and those were in NE MO...so will 
not mention thunder though a few moderate to heavier rain showers 
possible. Middle level short wave trough quickly exits NE of central Illinois 
by afternoon with skies becoming partly sunny. Highs in the low to 
middle 70s most areas with upper 70s in southeast Illinois from I-70 south. 


Weak high pressure builds east into Illinois by this evening from the 
Central Plains and passes east into the central Ohio Valley by dawn 
Monday. Progressive upper level flow brings a second stronger middle 
level short wave trough from the northenr rockies into Midwest Monday. 
This to increase clouds Sunday night from the west with a 20 to 
30% chance of showers later Sunday night over western Illinois. Best 
chance of convection will be Monday and Monday evening especially northwest 
of Lincoln as middle level trough drives a sharpening cold front southeast 
through central Illinois later Monday/Monday evening. Southeast Illinois could stay dry 
until sunset Monday evening and more sunshine to bring warmer highs 
in the low to middle 80s. Much cooler from the Illinois River northwest due to more 
clouds and showers around with highs in the upper 60s and lower 
70s. Storm Prediction Center said a few strong storms possible Monday afternoon/evening 
over central/southeast Illinois but no slight risk of severe storms since best 
instablity SW of MO and best upper level energy and wind fields 
north of central Illinois. Convection chances should diminish from northwest to 
southeast after midnight Monday night as cold front presses southeast toward the 
ohi river by dawn Tuesday as low pressure moves into the eastern Great 
Lakes. 


Long term...Tuesday through Saturday. 


Models continue to shower about a 1024 mb high pressure building 
into the Midwest Tuesday and Great Lakes Tuesday night. This to clear 
skies from the west Tuesday with highs in the middle to upper 60s from 
I-72 north and low to middle 70s in southeast Illinois. Cooled lows Tuesday night by a 
few degrees with middle to upper 40s central Illinois and lower 50s southeast Illinois. 
Large high pressure settles over New England Wednesday as upper level 
ridge noses northward into Illinois. This to keep it dry with warmer 
temperatures in the middle to upper 70s central Illinois and around 80f southeast Illinois. 
Extended models slower moving next weather system from The Rockies into 
the Midwest later this week and trending drier over central and 
especially southeast Illinois Thursday. Lower probability of precipitation Thursday especially eastern Illinois with 
better chance of convection Thursday night and Friday. 


Major Hurricane Ike moving west at 15 miles per hour packing winds of 135 miles per hour 
(category 4) near the turks islands taken by NHC into the central 
Gulf of Mexico Thursday. European model (ecmwf) has trended toward the GFS solution of 
bringing the remnants of Ike north-northeast across the Ohio Valley on Monday/Sep 
15 with heavy quantitative precipitation forecast over southeast Illinois. Still quite a bit of uncertainty 
that far out but will be interesting to watch Ike as it emerges 
into the Gulf of Mexico during middle week. 


Huettl 




&& 


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


$$ 

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