474 
fxus63 kdmx 051206 aaa 
afddmx 


Area forecast discussion 
National Weather Service Des Moines Iowa 
706 am CDT Sat Jul 05 2008 


Updated for 05/12z aviation discussion... 


Discussion... 
large area of high pressure over much of the lower Great Lakes and 
through the eastern Continental U.S. Will move slowly east today and allowing 
for return flow to develop by tonight. Gradual warming will occur at 
850 mb today allowing for some response at the surface with highs a few 
degrees warmer than Friday. The more significant push of Theta-E 
advection will arrive overnight tonight and this will bring the 
potential for elevated thunderstorms over the north...mainly after 
09z. Any storms that develop in the Theta-E advection zone with be 
have a difficult time sustaining a strong updraft with weak middle 
level flow ongoing. Some hints that an mesoscale convective system will dive out of South 
Dakota late. Probability of precipitation may need to be increased for this period with 
future forecasts if this remains on track. 


A frontal boundary is expected to be over central Iowa on Sunday 
with a Summer like air mass in place over the south and the best 
chances for thunderstorms over the north. Potential outflow 
boundaries from Saturday night convection leads to some uncertainty 
in boundary location. The boundary will remain the focus for 
thunderstorms Sunday night. Precipitable waters  will rise to near 2 inches during 
this period and with slow moving storms potentially training along 
the boundary...very heavy rainfall will be possible. A few lingering 
storms may persist on Monday before the main frontal boundary 
passage moves through Monday. Night. With moisture remaining 
abundant along with better shear to support organized updrafts...a 
severe...heavy rain producing mesoscale convective system may roll across the state. Will 
issue a hydrologic outlook for heavy rain threat during this period. 
Probability of precipitation begin to diminish from west to east on Tuesday with a slightly 
cooler and less humid air mass in place. 


&& 


Aviation...05/12z 


VFR conditions will continue through most if not all of the forecast 
period. Expect southerly surface flow becoming gusty by late 
morning. Latest models suggest possibility of mesoscale convective system impacting northern 
Iowa late tonight...mainly kfod/kmcw...but confidence level not high 
enough to mention in tafs at this time. 


&& 


Dmx watches/warnings/advisories...none. 


&& 


$$ 


Short term/aviation...Kinney 
long term...donavon