NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 292331
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
631 PM CDT Wed Apr 29 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Light rain ends from west to east during the late afternoon and
  evening. More showers expected on Thursday and possibly Friday.

- Frost Advisory for central WI late tonightinto early Thursday.
  Additional frost and freeze headlines expected over central and
  east central WI Thursday night and Friday night.

- Minor flooding persists on the Wolf River and Winnebago system.
  Water levels should gradually recede as the week progresses due
  to a lack of significant rainfall.

- Below normal temperatures expected through most of the period.

&&

.DISCUSSION...
Issued at 225 PM CDT Wed Apr 29 2026

Widespread light rain continues to develop across most of the
forecast area, in response to QG forcing ahead of a sharp
short-wave trough over western WI. The rain and clouds were
holding temperatures in the 40s. The rain will gradually taper
off from west to east during the rest of the afternoon and
evening, followed by partial clearing overnight. Partly cloudy
skies and light winds will allow temperatures to drop into the
middle 20s to middle 30s, which will allow frost to develop
in most areas late tonight.

Frost Headlines: Frost and Freeze headlines were started up along
and south of Hwy 29, plus Door County, today. Within that region,
temperatures dropping into the lower to middle 30s in central WI
late tonight should lead to widespread frost, so a Frost Advisory
has been issued for Marathon, Shawano, Wood, Portage, Waupaca and
Waushara counties from midnight through 8 am Thursday. Only patchy
frost is expected in the Fox Valley and lakeshore areas, so have
opted for no headlines there tonight. Potential for frost/freeze
headlines increases Thursday night and Friday night across all of
central WI, the Fox Valley and lakeshore areas.

Precipitation Chances: Persistent northwest flow aloft will bring
a series of short-waves through the western Great Lakes region
through the end of the work week. A short-wave is expected to
impact the forecast area during the late morning and afternoon on
Thursday, and pops have been increased a bit from previous
forecasts. In addition, a small chance of showers has been added
to eastern WI on Friday afternoon, as yet another wave passes
through. Given CAPE of <100 j/kg and unimpressive mid-level lapse
rates, we have removed any mention of thunderstorms during this
period.

Weak high pressure attempts to build into the region Friday night
into Saturday night, so the first half of the weekend looks nice.
WAA followed by a weak cold frontal passage will bring a chance of
showers on Sunday.

Stronger cold frontal passages are expected Monday and again
Tuesday night into Wednesday, along with a good chance of showers.

Temperatures: Given a persistent flow of Canadian air into the
region, it is not a surprise that temperatures will remain below
normal for much of the week. Some moderation in temperatures (to
near normal) should occur ahead of each of the cold fronts,
but reinforcing shots of Canadian air will follow the cold
frontal passages during the early to mid part of next week.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 631 PM CDT Wed Apr 29 2026

Patchy areas of MVFR cigs are lingering over eastern WI late this
afternoon within an area of light rain. Expect to rain to linger
through about 03Z before moving off to the east. West of a Y50 to
IMT line clouds have started to rise and scatter our as drier in
fills in behind the departing short-wave. BKN to OVC cigs based
around 4-6kft will redevelop over the region tonight. Thursday
another short-wave will swing through the region bringing another
round of light showers to much of region during the late morning
through the early evening. At times snow may mix in with the rain
across norther WI, mainly impacting RHI. Similar to today cigs/vsbys
should remain VFR much of the day, however, periods of MVFR
conditions are possible as showers move over any terminal.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from midnight tonight to 8 AM CDT Thursday for
WIZ030-031-035>037-045.
&&

$$

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