870 
fxus63 kgrb 151949 
afdgrb 


Area forecast discussion 
National Weather Service Green Bay WI 
249 PM CDT Wednesday Oct 15 2008 


Short term...tonight and Thursday. Main forecast focus to be on temperatures as 
incoming hi pressure to keep quiet conditions over the region. 


The 19z msas surface analysis indicated that the cold front was now east of 
the forecast area (ovr lake mi). A strong area of low pressure was situated over 
central Ontario...while hi pressure Sat over the plains. Vsbl satellite 
imagery showed low clouds remaining over WI as good cold air advection has allowed a 
SC deck to move into WI. Radar mosaic continued to show precipitation 
associated with the cold front pulling away from NE WI. 


The cold front and associated shortwave trough will continue to pull away from the 
region this evening...with the hi pressure beginning to build eastward from 
the plains overnight. Some remnants of cold air advection and cyclonic flow will 
linger early this evening...but clouds will gradually dissipate as 
drier air surges into WI. An exception to this cloud dissipation may 
be northern WI where northwest winds bring lake clouds inland from Lake Superior. 
Min temperatures will be totally dependent on this cloud sitn with any 
extended clearing allowing readings to really drop off. Have used 
the bias-corrected grids to start with...which ended up close to 
the previous forecast. 


The hi pressure is prognosticated to move into the upper Midwest/western Great Lakes 
on Thursday. Expect to see some fair weather cumulus developing in the morning... 
with more clouds across northern WI where northwest winds persist. There should 
be an increase in hi clouds later Thursday afternoon due to hi level moisture 
increasing ahead of warmer air spreading into the plains. A cool day 
on tap across NE WI even with mixed sunshine due to cool air aloft 
(8h temperatures at or below 0c). Some locations over northern WI will not get out 
of the 40s. 


Long term...Thursday night through Wednesday. Main forecast 
concern is precipitation chances Friday and this weekend. 


High pressure will be building into the region Thursday night. 
A 500mb trough will swing through the western Great Lakes on 
Friday...but high pressure will remain at the surface. NAM/GFS 
keep the County Warning Area dry for Friday under this ridge of high 
pressure...but they show quite a bit of moisture between 
800-900mb. European model (ecmwf) continues to show some light precipitation. With high 
pressure at the surface...can not see much precipitation in our 
area...but do expect increased cloudiness and maybe a few 
sprinkles. Will continue with a slight chance across the southern 
County Warning Area. 


Ridging at 500mb builds in Friday night with surface high 
pressure stretching from the Ohio Valley into the 
northeast...bringing dry weather into Saturday. 


Differences remain between the European model (ecmwf) and the GFS this weekend on 
how they handle a weak 500mb short wave and cold front. GFS brings 
in the cold front Sunday night...while the European model (ecmwf) does not push it 
through the area until Monday morning. However...the European model (ecmwf) tries 
to bring in very light quantitative precipitation forecast into northern Wisconsin Saturday night. 
This seems unrealistic...so will only keep slight chance probability of precipitation for 
the extreme northwest County Warning Area. Not expecting much rain from this front as 
there is not much upper support...but will continue with just 
slight chance probability of precipitation for Sunday through early Monday morning. 


Did lower high temperatures on Monday with decent cold air advection as 
Canadian high pressure pushes into the Great Lakes. Also lowered 
low temperatures Monday night as high pressure will be sitting 
overhead...clear skies and light winds are expected. No other 
major changes to the previous forecast. 
&& 


Aviation...current MVFR ceilings will lift to VFR ceilings late this 
afternoon/early evening and then dissipate as daytime heating 
wanes. VFR conditions to then prevail through 00z Friday. 
&& 


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


$$ 
Kallas/bersch