Weather

209 
fxus63 kind 071817 
afdind 


Area forecast discussion 
National Weather Service Indianapolis in 
215 PM EDT sun Sep 7 2008 


Discussion...broad upper troffing expeceted across the eastern half of the 
country into the middle of the week. Short WV trough currently 
dropping into the northern rockies expeceted to move eastward across the Great Lakes Monday 
night...dragging a cold front through the local area at that time. Models in 
good agreement with the main details. Forecast focus centers on probability of precipitation 
associated with this cold front. 


No sig weather expeceted tonight with surface hi pressure drifting over the area. Low level 
temperature gradient tightens up on Monday from northern Illinois into southern Michigan as a frontal system 
develops in that area. Appears the deeper lift/moisture will be on the 
cool side of the boundary with model data also suggesting air mass over 
the local area may be capped off most of the day on Monday. Based on 
above reasoning...will restrict probability of precipitation during the day on Monday to the northwest zones. 


Best precipitation threat should move over the area Monday night as lift...deep 
moisture...and surface fnt move through. Will go with likely probability of precipitation over the northern 
half of County Warning Area...tapering to chance farther S where lift will be a little 
weaker. Most of the model data suggest precipitation threat should be over by 
sunrise Tuesday...but will keep a chance pop in the eastern zones through the middle 
morning hours on Tuesday in case models are a little fast with the frontal 
timing. After that...dry weather expeceted through the middle of week with a large 
area of surface hi pressure moving across the area. 


Low level thicknesses suggest NGM MOS guidance looks OK for the most 
part...but may be under estimating the cold air advection in the later periods. Will shave 
a few degrees off of the MOS Monday night/Tuesday to cover this. 


&& 


Aviation discussion...for the 18z tafs 


VFR conditions through the taf period. A weak cold front will exit 
the area during teh first 6 hours of the taf period as weak high pressure 
over the plains builds across Indiana. Another weak short wave over South Dakota is 
expected to bring some VFR ceilings to Indiana overnight...but with dry 
forecast soundings and little in the way of lower level 
convergence...no precipitation is expected. 


The VFR ceilings will remain across the area through 18z on Monday. 


&& 


Ind watches/warnings/advisories...none. 


&& 


$$ 


Public...jas 
aviation...jp