685
FXUS63 KGRB 240453
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1153 PM CDT Tue Jun 23 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Chances for showers and storms at times from late this evening
  through Thursday evening. A few of the storms Wednesday
  afternoon and evening may become strong or severe, producing
  gusty winds and hail.

- Near to below normal temperatures most of the week, becoming
  above normal and humid early next week. Periodic chances for
  thunderstorms are also possible early next week, with the
  potential for severe weather.

&&

.DISCUSSION...
Issued at 326 PM CDT Tue Jun 23 2026

Precipitation/Thunder Chances...Pleasant conditions prevailed across
the region this afternoon as a cu field brought partly cloudy skies
to the area.

Upstream, satellite and radar imagery showed an area of showers and
storms over central MN driven by WAA from a nearly vertically
stacked low pressure system. This low is progged to move along the
Canadian/CONUS border into the Great Lakes through Thursday. This
will bring periods of showers and storms across the region from late
this evening through Thursday evening. The first of the waves will
still be driven by WAA moving across the area from west to east late
this evening into Wednesday morning. A few embedded thunderstorms
are possible, but severe weather is not expected with this wave,
rather PWATs of 1.25 to 1.50 inches would support brief heavy
downpours. The precip will become more isolated by mid-morning
Wednesday, with potential for redevelopment during the afternoon and
evening depending on cloud cover. If enough clearing occurs, the
combination of diurnal instability of 750-1200 J/kg and deep-layer
shear of 30-35 kts could support isolated strong to severe storms
producing gusty winds and hail, mainly across central and east-
central WI. As instability wanes after sunset, coverage will
decrease again Wednesday night, with isolated showers possible.
Additional isolated showers and storms are then possible Thursday
afternoon and evening due to diurnal instability up to 500 J/kg.

Models continue to indicate a stark pattern change occurring this
weekend with an upper-level ridge building over the area before
breaking down sometime during the middle of next week. This would
bring more summer-like conditions to the area with increasing Gulf
moisture and potential ridge riders resulting in thunderstorms at
times, including possible severe storms at times. Will continue to
watch how this pattern change evolves over the coming days for any
impactful weather.

Temperatures...Below normal temperatures in the low to mid 70s and
comfortable humidity levels will continue through Friday.
Temperatures then gradually warm to normal on Saturday and above
normal on Sunday through early next week with the ridging pattern
change. In addition to the warmer temperatures late this weekend
into early next week, dew points will also rise into the low to
possible mid 70s. If this pattern pans out, we could be looking at a
couple day stretch of heat-related impacts occurring.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1153 PM CDT Tue Jun 23 2026

Initial batch of showers faded as it moved into central WI. A few
light showers or sprinkles could occur before daybreak, with
better chance of showers with some moderate rain from southern Fox
Valley to lakeshore toward daybreak. Based on evening trends,
have removed mention of thunder at MTW late tonight as think best
chances for thunder will remain south. Cigs will be VFR initially,
but will drop to IFR/MVFR by Wednesday morning. Visibility may
drop to MVFR where heavier showers occur late tonight.

Scattered showers may linger on Wednesday morning as a warm front
lifts through, then a brief lull occurs late morning into early
afternoon. Addditional scattered showers and some thunderstorms
then develop by late afternoon (after 20z). Greatest probabilities
(>60%) for showers will be from central to north-central WI. Not
as certain on where thunderstorms will be though, so continue to
use PROB30 groups for now (CWA/AUW) and kept with only shower
mention elsehwhere. Where storms occur, an isolated strong to severe
storm is possible with gusty winds and hail.

&&

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

&&

$$

DISCUSSION.....Kruk
AVIATION.......JLA

NWS GRB Office Area Forecast Discussion