946 
fxus63 kgrb 211220 cca 
afdgrb 


Area forecast discussion...corrected 
National Weather Service Green Bay WI 
618 am CST Sat Nov 21 2009 


Short term...today through Sunday. 


Main forecast concern will be fog/freezing fog this morning. 


Weak area of high pressure working its way across the forecast 
area this morning. Residual low-level moisture...clearing skies 
and light winds have allowed dense fog to form across much of central 
and northern Wisconsin...with several locations reporting a quarter 
mile or less. Decided to go with a dense fog advisory generally 
west a line from Iron Mountain to Waupaca until about 15z. 
Surface temperatures across northcentral Wisconsin have also 
fallen to well below freezing...thus some slippery Road 
conditions are possible especially on bridges and overpasses. Infrared 
imagery also shows lingering middle-level clouds across parts of 
eastcentral Wisconsin which is holding temperatures up closer to 
40f in some locations. Visibilities in the Fox Valley currently 
in 2 to 5 mile range...but expect patchy areas of dense fog to 
develop here as well...especially west of Highway 41 before 
sunrise. 


After fog Burns off later this morning...expect mostly sunny 
skies with unseasonably mild temperatures...approaching middle 50s 
today. Normal highs this time of year around 40f. 


Expect some areas of fog to develop again tonight over much of the 
forecast area as weak high pressure slowly drifts off to the east 
and some low-level moisture works northward ahead of approaching 
shortwave trough. Increasing clouds ahead of the approaching 
shortwave and somewhat more wind in the boundary layer should 
prevent widespread dense fog Saturday night...however will let 
day shift reassess this possibility. Fox Valley area may stand the 
best chance for seeing patchy dense fog early Sunday morning. 


Mild conditions to continue on Sunday as southerly flow increases 
ahead of shortwave trough. Kept low chance probability of precipitation across western 
sections as best lift (albeit weak) should be approaching that 
area in association with rrq of upper jet. Any precipitation that 
does form later in the day is expected to scattered and rather 
light. 


Long term...Saturday night through next Friday. 


Medium range model solutions once again started doing their own 
thing by early next week. This once again led to HPC guidance 
being followed more closely than any of the 12z model runs. Rain 
chances were confined to the western part of the forecast area 
Sunday night...ahead of an approaching cold front. Precipitation 
chances continued into Wednesday as the HPC manual surface forecast 
brought a low through Wisconsin. Colder air in the wake of the 
system made precipitation type an issue for Tuesday night and 
Wednesday so both rain and snow were mentioned for those periods. 
Lake effect appeared to be a possibility across the extreme north 
and northeast starting Thursday...as Delta ts...lake surface to 
850mb...increase. Otherwise only went with some slight chance probability of precipitation 
across the area. Made a good Faith effort to blend well with 
surrounding forecast grids. 


Did not make major changes to high or low temperatures. 
&& 


Aviation...areas of dense fog expected at rhi...County Warning Area and auw through 
about 15z Saturday morning. Conditions to gradually improve to VFR 
thereafter. Some patchy fog possible again after 06z Sunday. 


&& 


Grb watches/warnings/advisories... 
dense fog advisory until 9 am CST this morning for wiz005- 
010>012-018-019-030-035-036. 


&& 


$$ 
Esb/eckberg