613 
fxus63 kdvn 300755 
afddvn 


Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois 
255 am CDT Sat Aug 30 2008 


Synopsis... 
high pressure to control our weather through early next week. Upper 
ridge then weakens allowing for strong cold front to push into the 
Midwest about middle week. European model (ecmwf) insists on bringing major Hurricane 
Gustav into la on Labor Day with remnants of Gustav then spreading 
tropical moisture into the dvn County Warning Area late in the week. Still remains 
to be seen how this all plays out and the eventual impact on our 
region but this has been a consistent signal. 


&& 


Short term...today and tonight... 
high pressure to guarantee spectacular weather for the region. With 
very dry airmass in place nary a cloud expected. Temperatures will 
rise rapidly today due to the dry air followed by a quick cool off 
tonight. Looking for about a 30 degree spread between the minimum 
and maximum temperatures. The unusual low dewpoints should also 
preclude fog formation despite near perfect radiational fog 
conditions...clear skies calm winds and middle to late August being 
climatologically favored for fog formation. 


.Haase.. 


Long term...Sunday through next Friday... 
upper level ridge shifts slowly east of the forecast area Sunday 
and Monday...along with the surface ridge that has held our weather 
very quiet the last day or two. The surface flow slowly turns from 
east to southeast...and temperatures slowly warm through the 
period. The wind flow is not the best for a large warm up...and 
have kept temperatures in the middle of the range of guidance values 
for Sunday...and closer to the warmer values on Monday. On Tuesday 
an upper level trough approaches the Midwest...with a surface low 
developing over eastern South Dakota. This surface low moves 
northeast across Minnesota and into Canada on Tuesday. The 
associated cold front drags across Iowa Tuesday...and across the 
forecast area Tuesday night and early Wednesday. Precipitation 
chances along the boundary appear to be in the low chance category 
for now...as the early morning timing is not auspicious. Behind the 
cold front the GFS indicates that a surface ridge builds in for 
Wednesday night and Thursday...and a shortwave moves across the area 
on Friday. The European model (ecmwf) brings the remnants of Gustav up over the area 
at the same time...and indicates precipitation chances for Thursday 
and Friday. Models have been shifting these features about these 
last few days...so will not be making any changes to Thursday and 
Friday at this time...and later shifts will have to re-evaluate 
these features. ... 


&& 


Aviation... 
nearly ideal flying conditions today through tonight. High pressure 
to ensure VFR with sky clear along with light winds. 


.Haase.. 


&& 


Dvn watches/warnings/advisories... 
Iowa...none. 
Illinois...none. 
MO...none. 


&& 


$$ 


Haase/le