546 
fxus63 kgrb 191934 
afdgrb 


Area forecast discussion 
National Weather Service Green Bay WI 
234 PM CDT Tuesday Aug 19 2008 


Short term...tonight and Wednesday. 


High pressure centered over the Eastern Lake Superior will 
continue to slide off to the southeast toward Lake Ontario by 
Wednesday afternoon. This high will continue to bring in cool and 
dry air into northeast Wisconsin tonight. However...the return 
flow on the back side of the high pressure will start to affect 
the area Wednesday with slightly higher dewpoints and temperatures 
jumping back into the low to middle 80s...except slightly cooler 
near the Lake Shore. Trended temperatures toward the higher mav for 
Wednesday afternoon. 


Instability will build across the western half of the grb County Warning Area as 
the high pressure moves to the southeast...with cape values 
approaching 500 j/kg...but with forecast soundings showing a 
decent cap around 700 mb and the surface boundary staying well to 
our south and west...continued with a dry forecast on Wednesday. 
Do expect diurnal cumulus to form by late morning. 


Long term...Thursday through next Tuesday. 


Main forecast issue during the long term is the speed and amount of 
moisture associated with Pacific system that moves across northern U.S. Thursday 
through Saturday. For the most part...most recent run of GFS and 
European model (ecmwf) in agreement on onset of precipitation and duration (not to mention 
decent run-to-run consistency). Initial convection develops on 
nose of low- level jet/warm air advection early Friday. Brief break before 
additional convection forms ahead of moderate shortwave/surface cold 
front. Current forecast in good shape...so little change needed. 


Questions on this scenario focus on amount of moisture and speed 
of system...thanks to tropical system meandering across the 
southeast part of the country. 


Temperatures through Saturday mainly above normal. 


Beyond the late week system...upper ridge builds back into Great 
Lakes. The remains of the tropical system will likely still be 
affecting the southeast U.S. The European model (ecmwf) and GFS indicates some northward 
movement of the remains into the Ohio Valley and eastern Great Lakes 
by the middle of next week. 
&& 


Aviation...VFR conditions are generally expected for the rest of 
this afternoon...with only a few lingering patches of 2500-3000 
foot ceilings late this afternoon. Patchy fog is possible late 
tonight across northeast Wisconsin. 
&& 


Grb watches/warnings/advisories... 
none. 
&& 


$$ 
Bersch/jkl