320 
fxus63 kind 181931 
afdind 


Area forecast discussion 
National Weather Service Indianapolis in 
322 PM EDT Friday Jul 18 2008 


Discussion... 


Forecast focus remains on temperatures and precipitation chances this weekend and early 
next week. 


High pressure ridge extended from the Middle Atlantic States to 
Kentucky. A quasi-stationary front extended from central lower 
Michigan to the Central Plains. Satellite shows a short wave over the 
Central Plains and models key on this tomorrow and are more 
aggressive brining in precipitation than previous runs for Saturday. Will 
go along with their higher probability of precipitation and add low probability of precipitation over our far northwest 
Saturday morning. 


This short wave moves on by Saturday night and a cold front moves into our 
area by Sunday. It is hard to key on any upper features for Sunday. 
However models indicate 850 mb Theta-E ridge across our area and GFS 
has convective available potential energy 2500-3500 j/kg by late Sunday. Storm Prediction Center has US under a day 3 
slight risk for Sunday. Will raise MOS probability of precipitation for Sunday and keep them 
in the chance category. 


In the extended period...things are more muddled. All the models 
stall the front across the middle Mississippi Valley and Ohio Valley 
and bring a series of short wave along this front. Timing of short wave are 
different between models as well. Will keep chance or slight probability of precipitation 
most of this time. The only period I decided to go dry was for our 
northern sections around Wednesday as European and GFS indicate a 
stronger high pressure over the Great Lakes. Used a MOS blend on 
temperatures for most periods. 


&& 








Aviation...discussion for 18z tafs 


Scattered cumulus will dissipate and winds will diminish after sunset. Expect 
MVFR fog to form once again as conds will be similar to previous nights. 
As with previous nights cannot rule out brief IFR conds at all xcpt ind 
but some high clouds moving in late should help keep things MVFR. 


Fog will burn off by 13-14z. Weak wave moving in from the west will 
bring in more middle and high clouds on Sat as well as a small chance 
for thunderstorms and rain. Chances too low to mention in tafs. 


&& 


Ind watches/warnings/advisories...none. 


&& 


$$ 


Aviation...cs 
public...jh