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Area forecast discussion 
National Weather Service Green Bay WI 
330 PM CDT Friday Aug 8 2008 


Short term...tonight through Saturday 


Primary forecast concern is precipitation chances Saturday. 


Middle-level vortex near Hudson Bay Canada late this after forecast to sink 
southward to near Lake Huron by 00z Sunday. This system will be 
the primary weather system to affect our weather next 24 hours. 
Latest NAM/GFS deterministic runs generally similar on timing of 
frontal passage across the forecast area for Saturday. Best estimate is 
frontal passage in the Green Bay area sometime between about 16z and 
17z...perhaps slightly faster than previous runs. Although 
boundary layer moisture limited and timimg not as 
favorable...upper dynamics associated with vupper ortex fairly 
strong and will at least brush the northeast portion of the 
forecast area. Continued chance probability of precipitation as per previous forecast for 
Saturday but bumped up frontal passage timing a bit. As front 
passes...boundary layer winds to shift to north/NE and increase to 15 
to 20 miles per hour. Decided to hold off on Small Craft Advisory for nearshore zones for now 
and let the evening shift take a closer look. 


Assuming a slightly faster frontal passage...bumped maximum temperatures for Saturday 
down a degree or two...especially across the northeast. 


Long term...Saturday night through next Friday. 


12z NAM...NGM...GFS all have precipitation out of the County Warning Area by 00z 
Sunday as surface high pressure builds into the region. Good 
agreement among the models on dry weather...at least through 
Monday. After that...uncertainty increases as models start to show 
more significant differences. Timing of precipitation is in 
question so have slight chance probability of precipitation going for Monday night and 
chance probability of precipitation on Tuesday...in most of the County Warning Area. Timing of the ending 
of precipitation is not a sure thing either with weak short waves 
forecast to pass through the state...so at least slight chance probability of precipitation 
remain in the grids through Friday. 
&& 


Aviation...expect generally VFR conditions overnight. 
&& 


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


$$ 
Esb/mg