Weather

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fxus63 kgrb 062030 cca 
afdgrb 


Area forecast discussion...corrected 
National Weather Service Green Bay WI 
329 PM CDT Sat Sep 6 2008 


Short term...tonight and Sunday. 


Short waves within a broad 500mb trough over the Continental U.S. Will be the 
main concern. 


Scattered showers over western Upper Michigan...northwest 
Wisconsin and northern Minnesota...associated with one of the short 
waves...should diminish somewhat around sunset. Lightning 
detection network also had some cloud-ground lightning but any 
thunder should remain north of the forecast area...closer to the upper 
support. A more solid area of showers and thunderstorms was over 
southwest Minnesota this afternoon and additional convection was 
over Iowa and northern Missouri. This was forecast to remain south 
of the forecast area during the night...but am not sure the models 
had a great handle on this. Have left out anything other than 
isolated showers in the north this evening. There will be a better 
chance of showers...and thunderstorms...across the area on Sunday 
with a more impressive looking short wave and an approaching cold 
front. Have chance probability of precipitation...approaching likely in central 
Wisconsin...by afternoon. 


Long term...Sunday night through next Saturday. Medium range 
models in good agreement with upper air pattern through the middle 
of next week. Then they differ in how quickly an upper trough 
moves out of The Rockies...probably due to differences in how they 
handle Ike. The European model (ecmwf) is faster and further north with the 
hurricane than the GFS...which may explain why the European model (ecmwf) is 
slower moving the upper trough eastward towards the Great Lakes 
and Midwest. The first significant feature in this forecast period 
is Monday and Monday night as a small but negatively tilted 
system lifts northeast towards Wisconsin. The differences aloft 
are not that great...but there is a big differences between the 
track of the surface low and northward extent of precipitation. 
Think that the GFS is too far north with the surface low...and 
also too far north and too heavy with precipitation. Neighboring 
offices seem to agree. So went more or less with NAM for the 
Monday through Tuesday period. Next chance of rain is Wednesday 
night and Thursday or possibly later...depending on movement of 
upper system from rockies. Seasonable temperatures expected for 
the most part. 
&& 


Aviation... 
ceilings and visibilities should be mostly VFR through the night. 
Scattered showers and isolated thunderstorms expected into the 
evening across the north. MVFR ceilings and visibilities return on 
Sunday with scattered showers and isolated thunderstorms. 
&& 


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


$$ 
Mg/rdm