Weather

987 
fxus63 kilx 070835 
afdilx 


Area forecast discussion 
National Weather Service Lincoln Illinois 
335 am CDT sun Sep 7 2008 


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 


&& 


Aviation... 
issued 1143 PM CDT Sat Sep 6 2008...for the 06z tafs 


Showers are continuing to progress across the County Warning Area. The lowest 
visibility upstream is at Macomb down to 3sm in rain. Will keep 
lowest visible only in the MVFR range for any taf site...mainly in a 
tempo. Will keep prevailing visible VFR...with tempos for any MVFR visible 
and ceilings. 


Any lightning strikes have been confined to the base of the upper 
trough...back in SW Iowa and northwest MO. It appears that secondary wave 
will shear out prior to reaching Illinois. Showers should diminish 
by sunrise...and no thunder is expected in our area. 


Was originally a bit too optimistic with clearing...so I am 
bumping it more toward midday...and will keep 3k-4k ceilings around 
longer. 


Shimon 
&& 


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


$$