Green Bay, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

370
FXUS63 KGRB 070815
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
315 AM CDT Sat Jun 7 2025

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Isolated showers late this afternoon into early this evening and
  again on Saturday.

- Widespread rain and thunderstorms are expected on Sunday and
  Monday. Severe potential remains low at this time.

&&

.DISCUSSION...
Issued at 315 AM CDT Sat Jun 7 2025

Main focus of the forecast period will be on the active weather
Sunday and Monday brought into the region by an upper low over
Canada.

A few isolated showers may return to portions of central and
east-central Wisconsin this afternoon, interrupting an otherwise
quiet and dry day. Diurnal heating will be the main driver,
producing at least a couple hundred Joules of CAPE by the mid to
late afternoon. Additionally the remnants of a shortwave will be
in the area, so kept a mention of some thunder will also be in
the forecast. Still, with minimal shear or other supporting
factors, would expect thunder coverage to be fairly isolated and
no severe or strong storms are expected.

More widespread active weather arrives late tonight through
Sunday morning as a stacked upper low over Canada brings the first
of a couple cold fronts into the region. The initial band of
showers and embedded thunder will move across the region quickly
through the morning and early afternoon hours as the initial cold
front races ahead its attendant shortwave. This would likely lead
to some steady weakening in this initial band as it gets away
from the upper support. Models then signal additional
destabilization during the afternoon behind the initial cold air
advection aloft, which would be contingent on sufficient clearing
but would would allow for some additional convection. As a
result, model trends have moved towards a one- two punch for
Sunday, with a second round of showers and storms in the late
afternoon and evening, generally focused towards north- central to
northeastern Wisconsin where the better shear parameters will be
at that time. Soundings for this second round generally show some
skinny CAPE profiles of 500-700 J/kg, which would certainly
support some additional thunder in the forecast but would not be
the greatest signal for strong or severe storms without additional
support. In order for this to change, the initial round would
need to move out earlier in the day, or the cold front and
shortwave energy would need to come into better alignment and
perhaps slow down their arrival on Sunday. Rainfall totals by the
end of the day are expected to sit between a half to 3/4 of an
inch at most locations, with only 20-30% chance of exceeding an
inch at any one location.

The stacked upper low will linger over the region Sunday night
through Monday before moving off to the northeast. Along the way,
a secondary cold front will be possible during the day Monday,
which will bring some additional rainfall to the region. Some
meager diurnal instability in the afternoon may again lend itself
to some thunder, but strong or severe storms again seem unlikely.
The bulk of the moisture will have advected out of the area by
this time as well, so rainfall totals for this second half
generally amount to just a couple of tenths.

A dry period then arrives for most of Tuesday and Wednesday.
Finally, long range guidance suggests that we may see a warm front
push into the region before stalling out as a stationary front
over our area for the end of next week. If this occurs, we may see
another longer period of rainfall each day along the front.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1014 PM CDT Fri Jun 6 2025

BKN mid-level clouds will likely persist through the night, and
given the expected cloud cover, confidence is too low to include
fog at any particular location overnight. Aside from the
lingering mid-level clouds, there is potential for SCT cumulus
clouds to form Saturday afternoon. Some models generate a few
showers and possibly an isolated thunderstorm in C/NC WI during
the afternoon/early evening, and plan to add PROB30 groups for
showers at AUW/CWA for a few hours. Looking at the latest smoke
models, don`t see any threat of significant surface-based smoke
through this TAF period.

Light E-NE winds will increase a little and become SE-S by
Saturday afternoon.

&&

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

&&

$$

DISCUSSION.....Uhlmann
AVIATION.......Kieckbusch