NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 251104
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
604 AM CDT Wed Mar 25 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Best chances of precipitation for the next week occurs Thursday
  (mainly rain) and Monday night into Tuesday (rain with a wintry
  mix over northern WI).

- Temperatures warmer today then cooling off by Friday into
  Saturday, before moderating again Sunday into Monday.

- Some rivers will remain above bankfull this week, but no
  flooding is expected. Potential for at least minor flooding
  could increase next week as pattern becomes more active.

&&

.DISCUSSION...
Issued at 152 AM CDT Wed Mar 25 2026

Frontal boundary remains mainly north through most of tonight.
Mid clouds should clear later this morning, resulting in a warmer
afternoon than yesterday. Becoming breezy with highs making a run
into the 60s over the mostly snow free regions of central WI, and
also in the typical warm spots northwest of the Fox Valley into
far northeast WI (Oconto, Wausaukee). Onshore southerly flow keeps
the Lake Michigan shoreline much cooler.

Approaching clipper low over western Canada slides over the western
Great Lakes late tonight into Thursday, dragging the front south
across the region. Precipitation with system arrives late tonight
in the form of mainly rain, with greatest chances from the morning
into the early afternoon on Thursday, though some lingering showers
may occur over eastern WI in the afternoon. Ptype generally rain
to start (maybe some snow mixes in far north), but as colder air
arrives in the afternoon from the north, precip could end as a mix
of rain/snow. Impacts should be minimal as sfc temps will only be
as cold as the mid 30s where snow occurs. Temps in the south may
push 60, though with precip it may be tough. Readings will fall
back in the afternoon into the upper 40s to around 50 as the front
works though. It will also become blustery all areas with northerly
winds gusting to 20-25 mph behind the front. Even higher gusts are
possible near Lake Michigan.

Northerly winds will keep conditions seasonably cool Friday into
Saturday. There could be a few periods of light snow or flurries
with shortwaves dropping through in northwest flow aloft. Not
looking to be anything of note though.

High pressure shifts east Sunday into Monday, allowing warmer
and dry conditions to return to the western Great Lakes. Highs
will be in the 60s by most areas on Monday. After this though the
pattern becomes quite active for much of next week with deep trough
becoming established over the the western CONUS and a persistent
frontal boundary from the plains to the Great Lakes. Strong mid to
upper level wind energy along with periods of focused low-level
jets aiming into the frontal boundary will help to increase Gulf
moisture and instability, suggesting multiple rounds of showers
and some thunder as well. Primary concern will be potential for
periods of heavy rain as this could lead to increasing hydrology
issues. Looking at LREF, NBM 90th percentiles for 24hr precip
ending at 12z Tue, 12z Wed and 12z Thu indicate any of these days
could carry the potential for heavy rain. Will all depend on how
the convection trends play out. Does also appear there could be
wintry component to the systems over northern WI initially (snow,
ice), then across more of the area as the week progresses. WSSI-p
shows at least some risk for minor impacts next week.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 603 AM CDT Wed Mar 25 2026

VFR conditions will prevail into this evening as bkn-ovc mid clouds
gradually thin out this afternoon. Low-level jet aloft with weak
inversion results in LLWS to start the morning, then as inversion
dissipates and mixing deepens, expect SW sfc winds to become gusty
to 15-20 kts by this afternoon. Winds will become lighter
tonight, but there will be another round of marginal LLWS this
evening at GRB/MTW.

Arrival of cold front from the north late tonight will bring
deteriorating conditions over north-central and central WI. Cigs
will drop to IFR/MVFR over northern WI after 10z-11z (including
RHI). Light rain will begin to impact CWA/AUW/RHI around the
same time. This light rain and patchy fog will then expand to the
rest of the TAF sites on Thursday morning. Cigs on Thursday will
become IFR/MVFR as the front sinks southward across the area and
gusty N-NNE winds develop behind it. The light rain may mix with
light snow in the afternoon from northern WI to far northeast WI
as colder air arrives in the wake of the front.

Even as the precipitation ends late Thursday afternoon, expect
IFR-MVFR cigs to persist into Thursday evening before slowly
clearing out.

&&

.HYDROLOGY...
Issued at 152 AM CDT Wed Mar 25 2026

Several rivers will remain above bankfull this week as the snow
continues to gradually melt and make it into the rivers. Despite
high water levels in some areas, no significant flooding is
anticipated at this time. We will need to keep eye on active
pattern that could develop next week. If signals for thunderstorms
and heavy rain come to fruition, the potential for at least minor
flooding would increase on many rivers, especially as many northern
areas will still have snow cover at that point.

&&

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

&&

$$

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