112
FXUS63 KGRB 251902
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
202 PM CDT Wed Mar 25 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

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

- Temperatures cooling off 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 202 PM CDT Wed Mar 25 2026

A mid-level thermal ridge gradually pushing east today has brought
partial clearing to the region this afternoon. Areas in central WI
where clearing is more prevalent are warming quickly through the 50s
and should reach highs in the 60s later this afternoon. In contrast
south southeast onshore flow has remained along Lake Michigan
keeping those areas in the upper 30s to 40s.

The next chance for widespread precipitation comes overnight into
Thursday morning as a short-wave, currently coming onshore over the
PNW drags a cold front toward the western Great Lakes. Precipitation
should predominantly be rain as it spreads east through Thursday
morning with surface temperatures above freezing. High-res models
are in generally good agreement that the greatest rainfall amounts
(0.2-0.3 inches) will be focused along and north of HWY 29. 12Z HREF
shows a narrow corridor of 10-30% probs for greater than 0.5 inches
north of HWY29 and south of HWY 8. With a few points along both the
Wisconsin and Wolf rivers already at or near bankfull will need to
watch these possible higher end totals as they could increase the
risk for minor river flooding into next week. As the rain begins to
depart the region Thursday afternoon surface temperatures behind the
front do cool below freezing across northern which may lead to a
brief transition to snow with a tenth or two of accumulations
possible along the WI/UP border.

For Friday did introduce some 15-30% PoPs mainly across northern WI
as a subtle short-wave moving through the northwest flow may spur on
some scattered flurries or snow showers. Thermal profiles also
support this with mid-level lapse rates steepening to 7-8 C/km.
Total accumulations should be minimal with NBM showing only a 10%
chance for greater than 1 inch across far north-central WI.

Saturday and Sunday should be dry seasonal days as high pressure
builds over the western Great Lakes. High pressure shifts east
Sunday night 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 18Z TAF Issuance
Issued at 1252 PM CDT Wed Mar 25 2026

VFR conditions will prevail across the region through this afternoon
and evenings as sct-bkn mid-level clouds clouds stream over the
region. Surface winds will gradually veer around to the southwest
this afternoon with gusts increasing to 15-20 kts.

Conditions will begin to deteriorate overnight as a cold front
approaches the region. Cigs will quickly lower to MVFR/IFR from west
to east beginning after 10Z. Along with the lower cigs an area of
widespread light to moderate rain will move across the northern half
of the state Thursday morning into the early afternoon. Vsbys may
drop as low as 2-3SM at times within the heaviest rain. Rain may
transition to snow for a short period across far northern WI
Thursday afternoon, but snow should have minimal aviation impacts.
Precipitation will come to an end from west to east during the late
afternoon and evening, however, even as rain ends cigs will be slow
to rise.

A period of LLWS is also possible this evening at ATW, GRB, and MTW
as winds atop a low-level inversion increase to 30-35 kts.

&&

.HYDROLOGY...
Issued at 202 PM 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 along with
addtioanl rain expected on Thursday. 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 significantly increase on
many rivers, especially as many northern areas will still have snow
cover at that point.

&&

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

&&

$$

DISCUSSION.....GK
AVIATION.......GK
HYDROLOGY......GK

NWS GRB Office Area Forecast Discussion