421
FXUS63 KGRB 180640
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
140 AM CDT Sat Apr 18 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

-Minor to major flooding will continue into next week with the
 greatest impacts expected on the Menominee and Wolf Rivers where
 major and record breaking flooding is occurring.

-No significant precipitation is expected through next Thursday.
 Widespread showers and storms chances return Thursday night into
 Friday.

-Temperatures will be seasonally cool through this weekend with a
 gradually warming trend expected next week.

&&

.DISCUSSION...
Issued at 135 AM CDT Sat Apr 18 2026

A strong CAA regime has set up over the forecast area early this
morning in the wake of a strong cold front. Temperatures across the
area have fallen 20-30 degrees behind the front with most areas now
in the middle 30s to 40s. Scattered shower activity is also trending
down behind the front early this morning. For today cool and mostly
dry conditions are expected, however, with upper level troughing
linger over the area and nearly dry adiabatic low level lapse rates
scattered instability showers/flurries are possible (20-40%) late
this morning through the afternoon. Localized precipitation amounts
of a few hundreths up to a tenth of an inch are possible, mainly
across northern WI. Temperatures today will be seasonally cool
with highs only reaching the upper 30s to 40s and overnight lows
falling into the 20s to low 30s across the forecast area.

With lingering troughing over the area Sunday another round of
instability showers/flurries will be possible (20-30% chance) mainly
across central to east-central WI. Precipitation amounts should again
remain generally less than a tenth of an inch across the region. The
cool temperatures also stick around through the end of the weekend
with highs again in the middle 30s to 40s Sunday.

Ensemble upper-level flow fields support a ridge building over the
upper Great Lakes through the first half of next week bring a much
needed proloned dry stretch. Temperatures are also expected to
gradually warm through next week. Long range ensembles favor next
Thursday into Friday for the next round of widespread showers and
thunderstorms. Synoptically an upper trough is forecast to dig into
the northern Plains spurring on an area of surface cyclogenesis.
along the US/Canadian border. This would place much of our forecast
area in the warm sector making stronger thunderstorms possible
Thursday night into Friday. NCAR AI convective hazards forecast
is already painting 5-15% probs across much of WI during this
time.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1148 PM CDT Fri Apr 17 2026

Cold front moving across northeast WI during the late
evening will bring an abrupt wind shift to KGRB/KATW
and KMTW by 06z. As the front pushes to the east of
the areas, scattered showers and isolated storms
will come to an end overnight. Along and just
behind the front, there will be a brief period of
IFR CIGS, otherwise CIGS in the MVFR category should
rise into the VFR category on Saturday. A few light
sprinkles or flurries may mix in with the clouds in
the late morning and afternoon. Gusty west to
northwest winds of 15 to 25 kts with gusts to 30 kts
will continue through Saturday afternoon, before subsiding
Saturday evening.

&&

.HYDROLOGY...
Issued at 135 AM CDT Sat Apr 18 2026

MRMS 24-hr QPE shows a narrow swath of 2-3" of rainfall from
northwest Wood Co. to southern Langlade Co. with lesser amounts of
0.25-0.75" across the rest of the forecast area. This will likely
lead to brief rises on rivers in central WI, mainly the Wisconsin
River. A small area of these higher end totals did fall in the
northern extend of the Wolf River basin which will slightly delay the
eventual crest and recession of the major flooding that continues
along the Wold River at New London and Shiocton. Additionally the
Menominee river will remain in minor to major flood stage through
this weekend due to recent rainfall and continued snowmelt in Upper
Michigan. If you live near a river or stream, continue to monitor
the latest hydro forecasts and Flood Warnings from the National
Weather Service in Green Bay.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 AM CDT this morning for WIZ011>013-019>022-
030-031-035>040-045-048>050-073-074.
&&

$$

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

NWS GRB Office Area Forecast Discussion