NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 281052
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
552 AM CDT Sat Mar 28 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- A bit on the cool side today, then warming trend through early
  next week. Greatest potential for highs in the 60s from central
  WI to the southern Fox Valley Sunday through Tuesday.

- Potential for stronger thunderstorms and locally heavy rain
  Monday Night into Tuesday, then drying out Wednesday into
  Thursday. Another system may bring rain and snow late next
  week.

- Many rivers at or above bankfull into next week. Isolated
  instances of minor flooding may still occur on some rivers.

&&

.DISCUSSION...
Issued at 239 AM CDT Sat Mar 28 2026

Generally quiet weather weekend expected. Isentropic ascent
shifts across especially northern sections today. GFS/FV3 family
still on its own showing precip. Virga maybe, but think precip
will be stretch given dry low-levels. The dry conditions will be
noticed today. Lower RH and gusty southwest winds will result in
elevated fire weather conditions into our far southwest (Wood
County). Opted to not issue SPS given the midday/afternoon
expected cloud cover which will hold down max temps in the mid
40s. Much warmer across the board on Sunday, with 80% chance of
seeing 60 along and south of highway 10. Not as windy as today
though.

Majority of the weather in the next week occurs late Monday
through Tuesday evening, with another system potential for late
week. No big changes to overall synoptic look with mid-level
trough northern plains supporting low pressure and a developing
warm front extending to the east into the western Great Lakes by
late Monday. Low then slides to western Great Lakes Monday night
with a cold fropa expected sometime on Tuesday. Models agree that
highest chances for showers and storms in our area will occur
Monday night into Tuesday as low-level jet is aimed into the warm
front leading to elevated instability rooted at 800-700mb up to
1000j/kg and PWAT over 1 inch overhead (nearing the max for the
date). Effective shear is around 30 kts, so it all adds up to
potential for a few stronger storms and locally heavy rainfall
from the stronger storms. In terms of wintry impacts early this
week, trends continue to show this being pretty much a non-factor,
with NBM v5.0 showing less than 10% chance of any snow or ice
over far north-central as temperatures are only shown to be in the
mid to upper 30s.

LLJ quickly veers to the WSW on Tuesday, so think the greatest
severe risk will be south and southeast of our area by afternoon
as shown by recent NCAR AI/Machine Learning convective hazard
forecasts. In fact, good agreement sfc cold front will be through
the area by afternoon. Granted, the mid-level jet that will help
form this system is still diving across the Pacific to the south
of Alaska this morning, so certainly time for changes in these
details. These are the current trends though. Main question as it
stands now is will there be another wave lifting across the area
to the north of the front to lead to secondary round of moderate
stratiform type rain in the afternoon. Canadian leading the way
with that idea right now, but other models and NBM/LREF ensembles
not as on board. Kind of important detail though as colder air
working in from the north late Tuesday into Tuesday night would
lead to a mix of rain/snow if there is still precip around at that
point. In wake of this system ECMWF idea from last couple days
looks to win, with dry, chilly weather then ensuing Wednesday and
Thursday.

Next system comes in late next week. Cannot rule out some wintry
component to the system as models/ensembles show a stronger low
tracking across the region Friday into Saturday with sufficiently
cold air on the backside to support rain/snow or snow.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 551 AM CDT Sat Mar 28 2026

VFR conditions with intervals of mid and high clouds through the
period. Cigs will be as low as 080-100 this afternoon.

Light SW winds increase to 10-15 kts by this afternoon with gusts
20-25 kts. SW winds diminish this evening, but LLWS will develop
and last through the end of the TAF period.

&&

.HYDROLOGY...
Issued at 239 AM CDT Sat Mar 28 2026

Several rivers will remain at or above bankfull into next week due
to recent/ongoing melting snow along with the rainfall we saw this
last Thursday. Ensemble river probability forecasts still show
some potential for isolated points on a few rivers to reach minor
flood stage next week, but trends for multiple locations to see
potential for minor flooding are not as bullish. If heavy rainfall
ends up being more widespread instead of tied to smaller
complexes of thunderstorms, the risk for flooding would increase
over more of the area as the grounds are more saturated and rivers
are already running higher.

&&

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

&&

$$

DISCUSSION.....JLA
AVIATION.......JLA
HYDROLOGY......JLA