876 
FXUS63 KGRB 281118
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
618 AM CDT Fri Jun 28 2019

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 422 AM CDT Fri Jun 28 2019

Upper winds veering to the northwest and cool 
outflow from convection will combine to push a weak cold front to
the south today. The air behind is not much cooler or drier but
should be enough to keep precipitation mostly to our south once 
the current activity exits the area. Highs today will be close to 
normal. 

Clearing skies, light winds and wet ground may combine to produce
a relatively rare mid summer fog event late tonight. Areas of
dense fog could from after midnight and continue until an hour or
so after sunrise. Fog over the lake and bay could last a bit
longer. Lows will be close to normal.

Saturday will be sunny and very warm with dewpoints falling a bit,
especially in the north. Highs will be five to eight degrees
above normal.

.LONG TERM...Saturday Night Through Thursday
Issued at 422 AM CDT Fri Jun 28 2019

Main concerns for this forecast period are the hot and humid
conditions on Sunday and the potential for intermittent showers 
and thunderstorms through the middle of next week.

Saturday night through Sunday morning...An upper-level ridge axis
will extend from Hudson Bay to the Upper Mississippi Valley
ultimately keeping conditions dry for Saturday night. As the ridge
shifts further east into Sunday morning and begins flattening over
the Upper Mississippi Valley, a surface low pressure system over 
northern Manitoba will also shift further east. The cold front 
associated with this low will extend from northwest Ontario to the
Northern Plains. The majority of model guidance is in agreement 
with keeping the forecast area dry Sunday morning, however, the 
GFS and NAM indicate a disturbance ahead of the main cold front 
would bring some showers and storms to the forecast.

Sunday through Monday...Model guidance is in agreement with the 
overall evolution of the upper-level flow flattening out over the 
Northern Plains and the cold front extending across the Upper 
Mississippi Valley into the SD/WY/NE border. With the forecast 
area being in the warm sector on Sunday afternoon, max 
temperatures will be in the 70s along the lakeshore and middle 80s
to lower 90s elsewhere. Dew points will also be higher making it 
a muggy day. Model guidance remains uncertain with the timing of 
the cold frontal passage. Therefore, depending on when the cold 
front will move over the region, the potential for stronger storms
may be possible from Sunday afternoon through Monday.

Rest of extended...By Monday night, the cold front will sag into
southern Wisconsin and remain parallel with the upper-level flow.
Model guidance indicates this front will stall across southern 
Wisconsin and northern Illinois through Tuesday. This will keep
chance PoPs for showers and storms across the region through
Tuesday. However, there is also evidence of the zonal mean flow
continuing through the rest of the extended, keeping the chance
PoPs through the remainder of the week.
&&

.AVIATION...for 12Z TAF Issuance
Issued at 618 AM CDT Fri Jun 28 2019

Showers will end over eastcentral Wisconsin this morning
as a weak cold front moves south. IFR conditions in northcentral 
Wisconsin should dissipate by midday. Skies should clear across 
the entire area by late afternoon. 

With clear skies and light winds, dense fog could form late tonight
over much of the area, with LIFR possible between 08z and 11. VFR
conditions are expected Saturday once any ground fog dissipates.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....RDM
LONG TERM......Hykin
AVIATION.......RDM