NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 150735
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
235 AM CDT Mon Jun 15 2026

.KEY MESSAGES...

- 30-50% chance for non-severe storms across northern Wisconsin
  late this afternoon and evening, but brief gusty winds are
  possible.

- Additional showers and storms (60-90% chance) Tuesday and
  again later Wednesday into Wednesday night. Chances for
  organized severe weather remain low, but a few strong storms
  with small hail, gusty winds and heavy rainfall may occur.

- Below average temperatures in the 60s and 70s through the
  week.

&&

.DISCUSSION...
Issued at 235 AM CDT Mon Jun 15 2026

Today-Tonight:

Isolated to scattered storms (30-50% chance) may develop across
northern Wisconsin within a modestly unstable and seasonably dry
environment this afternoon/evening. Overall, the environment is not
supportive of organized severe weather, but steepening low-level
lapse rates with diurnal heating within a dry boundary layer may
support gusty outflow winds with any storms before stabilization
occurs during the evening.


Tuesday-Wednesday:

Two prominent shortwave troughs will impact the area through mid-
week. The first will move through on Tuesday. Again, boundary layer
heating beneath seasonably cold (<10th percentile relative to climo)
500 mb temps will result in a diurnal uptick in showers/storms. Deep
layer shear will be quite weak, keeping storms primarily
pulsy/disorganized in nature. However, any stronger storms may
produce small hail given the cool temps aloft.

The stronger wave and associated surface low will quickly approach
around the southern periphery of the broad trough of low pressure to
the north over central Canada on Wednesday. Deep layer wind fields
are quite impressive, with the ensemble mean EPS/GEFS/CMC 500 mb
winds forecast near the top of climatology for this time of year
southward across Iowa and Illinois within the jet core south of the
wave. Although there is still some spread in the track of the
surface low, the greater moisture return/instability is more likely
to remain south of the area. Thus, at this time, the greater severe
weather risk looks to remain south of the area, but will have to
monitor trends with this very dynamic system. This system
likely will bring widespread rainfall (50-80% chance for greater
than 1/2 inch) with locally higher amounts likely to be
influenced by the strength and placement of convection.

High temperatures will be limited to the 60s and 70s during this
time, dependent somewhat on the extent of clouds/showers.


Thursday-Sunday:

Northwest flow aloft will continue through the rest of the week with
some indication for gradual deamplification of the flow by next
weekend. Gradual warming should occur, but overall, near to
below average temps remain favored through next weekend.

There is less signal for organized precipitation late in the week
into the start of the weekend with predictability of embedded
shortwave troughs decaying at this range. Consequently, rain chances
are on the low end (20-50%) through this time period right now.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1005 PM CDT Sun Jun 14 2026

VFR conditions are expected to prevail through the TAF period across
the forecast area.

Skies are expected to remain mostly clear across the region tonight.
A scattered fair weather cu field is expected to develop Monday
morning based around 3.5-4 kft initially, but rising through the
day. There is a chance for a round of scattered showers and isolated
thunderstorms, mainly across northern WI Monday afternoon and
evening beginning around or after 22Z. Have framed out the best
timing for showers at RHI with a PROB30 group for now.

West winds are not expected to be as gusty Monday, however, gusts up
to 20kts will be possible again beginning after 14-16Z.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...None.
MARINE...None.

&&

$$

DISCUSSION...JM
AVIATION...GK