NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 301002
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
502 AM CDT Wed Apr 30 2025

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Next opportunity for rain is Wednesday night through Friday.
  Expecting mainly rain, thunder chances are low.

- Dry and warmer weather this weekend and into early next week.
  There is a 50-80% chance of high temps of 70+ on Sunday away
  from the lake sore.

&&

.DISCUSSION...
Issued at 502 AM CDT Wed Apr 30 2025

Low clouds formed off of Lake Michigan and expanded westward
overnight, which has left much of the forecast area under a low
cloud deck. Easterly winds have also held up, contributing to the
expansion of these clouds. Therefore, temperatures have remained a
little warmer than expected in the mid 30s for most locations as
of 09Z. Places where skies were still clear (Land O' Lakes and
northern Door County) were cooler and had calm winds.

It took models a bit to pick up on this cloud trend, mainly
followed the HREF and NBM for cloud coverage today. Low clouds
continue to hang around through midday, and then scattered out as
winds veer to the south. This is quickly followed by increasing
high clouds ahead of the next weather system. So, looking at a
partly to mostly cloudy sky today, which may have a slight
influence on temperatures. But, the late day warm advection and
any breaks in the clouds should help. Forecast highs are in the
upper 50s and low 60s, and cooler along the lake shore in the mid
40s to low 50s.

Focus shifts to a few rounds of rain from tonight through Friday.
There is a shortwave/sfc low moving up from the southwest,
quickly followed by one from the northwest. Still some timing and
track differences, but either way overall impacts will be low.
First low approaches tonight and moves south of WI on Thursday.
Some models have pulled this farther south, leading to little
precip getting into the GRB forecast area; while others still
bringing in light rain, at least for the southern half. Slowed
down arrival of PoPs until around or after midnight which continue
through Thursday. Just as this system departs a shortwave/low
moves in from the northwest, bringing another round of light to
moderate Thursday night into Friday morning. With some lingering
moisture and lift possibly into Friday afternoon--especially
across northern WI. Rainfall totals from 12AM Thursday through 7PM
Friday range from ~0.25 to 0.50 inches, which does not trigger
any flooding concerns. Cannot rule out some embedded thunder on
Thursday with a few spots of 100-200 J/kg of CAPE present, but
overall thunder chances are low and severe weather is not
expected.

High pressure builds in for the weekend leading to pleasant
weather conditions. Dry weather is expected from Saturday through
at least Monday, with high temps in the 60s on Saturday, and 70s
for most from Sunday-Wednesday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1149 PM CDT Tue Apr 29 2025

As winds have turned east this evening, low-level moisture (MVFR
cigs) has shifted across northeast WI. This will impact GRB and
RHI into the overnight, potentially affecting AUW/CWA late
tonight. East winds have developed at GRB/ATW/MTW and these will
shift to the rest of the terminals overnight.

On Wednesday, any low-level clouds will dissipate early, leaving
just increasing high clouds from the south. Winds will be light
from the southeast. Clouds will thicken on Wednesday evening,
remaining VFR. The first light showers will begin to move into the
area from the south toward the end of the TAF period late on
Wednesday evening. The highest rain chances with the system the
rest of Wednesday night into Thursday will be over east-central
and northeast WI.

&&

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

&&

$$

DISCUSSION.....KLJ
AVIATION.......JLA