139
FXUS63 KGRB 061047
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
547 AM CDT Sun Jul 6 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Seasonal summer weather is expected over the next week. Shower and
thunderstorm chances (50-60%) return Monday night and Tuesday, risk
of severe storms is low (less than 10%).

&&

.DISCUSSION...
Issued at 229 AM CDT Sun Jul 6 2025

Today...

Main focus for this morning is any fog development as skies begin to
clear out across northern WI. With yesterday`s rain there is plenty
of low-level moisture and surface obs show winds have become calm
across most of the region. Fog is most likely to develop in north-
central WI where clouds are stating to erode. A few sites in
northwest WI have been reporting fog for several hours. Think this
fog may spread into Vilas and parts of Oneida counties with lower
confidence the fog spreads further south and east. Any fog that does
develop should burn off fairly quickly this morning.

A cold front continues to slowly sag southeastward toward southern WI
early this morning. This will keep light scattered showers going
across eastern WI through mid-morning. Ridging then begins to build
in from the west returning dry weather for the remainder of the day.
Temperatures will be about 10 degrees cooler than yesterday with
highs this afternoon reaching the low 70s to low 80s. Humidity will
also be noticeably lower today as dew points fall into the middle
50s to low 60s across the region.

Behind the front northerly winds will be breezy this afternoon,
particularly along the lakeshore with winds 10-15 mph gusting up to
25 mph at times. The increasing winds may make for choppy waters
along Lake Michigan, but though conditions were too borderline to
justify a Beach Hazard or Small Craft Advisory.

Work Week Forecast...

Temperatures this week are forecast to trend near normal with highs
in the upper 70s to middle 80s each day. Humidity will also be lower
as dew points sit in the upper 50s to low 60s for much of the week.

Ridging will continue to build over the western Great Lakes Monday
keeping the region dry. Global ensembles show the ridge beginning to
break down during the middle of the week as several weak short-waves
move through the upper-level flow. Fist of these waves is progged to
pass over northern WI Monday night returning shower and storm
chances (30-50%) through Tuesday. Instability and available
moisture are not expected to be all that impressive (400-600 J/kg
SBCAPE and 1.4-1.5" PWATs), so think the risk for any severe
storms is very low (less than 10%) Tuesday. Another short-wave
arriving later in the week may bring another round of showers and
storms Friday into next weekend. Ensembles show a slightly more
favorable environment for stronger storms during this period, but
there remains a great deal of uncertainty with the timing and
intensity of any storms.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 546 AM CDT Sun Jul 6 2025

A low status deck and light scattered showers has developed north
and west of a sagging cold front currently extending from SUE to OSH.
Cigs are LIFR/IFR at most terminals, except in central WI where
clouds have started to erode creating VFR conditions. Cigs should
rise through this morning to MFVR before scattering out this
afternoon. VFR conditions are then expected for the remainder of the
day.

There is a chance (10-20%) for dense fog to develop across portions
of central and northern WI overnight. Included TEMPO groups with IFR
vsbys at AUW, CWA, and RHI early Monday morning to account for any
fog, but it is uncertain if it will form or not.

Northerly winds today will increase and become breezy. Periodic
gusts to 20-25 mph are possible this afternoon, strongest across
eastern WI.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....GK
AVIATION.......GK