NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 181134
AFDGRB

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

Updated aviation portion for 12Z TAF 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 12Z TAF Issuance
Issued at 634 AM CDT Sat Apr 18 2026

Blanket of MVFR status has developed over the region overnight. As
the cold air advection continues to bring drier air into the region
this morning expect status to start scattering out. This trend is
already occurring upstream over northwest WI. With the linger
troughing over the region scatter pop-up rain and snow showers will
be possible late this morning through this afternoon across much the
region, however, expect aviation impacts to be minimal.

Northwest winds will continue to be breezy today with frequent gusts
of 20-25 kts and peak gusts around 30 kts.

&&

.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...
None.

&&

$$

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