023 
fxus63 kgrb 192020 
afdgrb 


Area forecast discussion 
National Weather Service Green Bay WI 
320 PM CDT Friday Mar 19 2010 


Synopsis..split flow expected across noam pretty much through the 
forecast period. For the most part...forecast area will remain between 
branches of the split...so the Prospect for sig widespread precipitation will 
be low. Temperatures won't be as unseasonably mild as they were this 
week...but with the snow cover now gone readings should average at 
least somewhat above normal for the period. 
&& 


Short term...tngt/Sat. Band of precipitation driven by middle-level 
frontogenetic forcing and enhanced by rrq of upper jet shiftg northeastward 
and away from the area will affect the southern part of the forecast area late 
this afternoon and this evening. Toyed with probability of precipitation right up to the last 
minute...but have finally decided to go with likely probability of precipitation across the 
far southern/southeastern part of the area. Precipitation will probably start as rn...then 
change to snow as evap cooling brings down boundary layer temperatures. 
Temperatures aloft likely already cold enough for snow. Warm surfaces 
should keep any accumulations minor and confined to grassy areas. 


Also of note is secondary cold front that will drop southeast across the area 
this evening. Canadian model and RUC seem to handle this best...and 
drop it south-southwestward over eastern WI as a backdoor cold front. Adjusted grids 
to follow that idea...and bring surge of northeasterly winds down the Bay and 
lake. Although temperatures will fall off fairly quickly as precipitation develops... 
Don/T expect overnight lows to drop too far with clouds and winds...so 
stayed toward the warmer side of guidance. 


Precipitation should be S of the area by tomorrow morning. But expect decr 
clouds...so some recovery in temperatures is likely. Used blend of guidance. 


Long term...the models are in pretty good agreement with the 
upper air pattern...keeping all the action south of here through 
the end of next week. Some flurries or sprinkles possible during 
the middle of the week as a weak upper system passes by to the 
north and again Friday as some colder air arrives from the 
northwest. Some difference between the GFS and European model (ecmwf) as to the 
timing of the colder air but thats far enough away to tweak later 
on. 
&& 


Aviation...MVFR ceilings acr the north should overspread most of the area 
tonight...but dissipate Sat as drier air works into the region. 
&& 


Marine...expect to flirt with Small Craft Advisory criteria this 
evening behind the backdoor front. Much of the Bay still iced 
over...but there is now a lot of boat traffic in the vicinity of the 
mouth of the Fox River as the walleye fishing is picking up. Still 
some question about how strong winds will be when front reaches that 
area this evening. Will advise evening shift to monitor closely... 
and may need an mws if if surge of winds down the Bay is 
significant. 
&& 


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


$$ 
Skowronski/rdm