FXUS63 KGRB 200728
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
228 AM CDT Wed May 20 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Frost or freeze headlines may be needed tonight as lows fall
  into the low to mid 30s over the Northwoods.

- Below normal temperatures continue throughout the week, warming
  back up during the Memorial Day weekend.

- Dry through at least early Friday with periodic rain chances 
  throughout the Memorial Day weekend.

&&

.DISCUSSION...
Issued at 228 AM CDT Wed May 20 2026

Early Morning Analysis...Despite surface high pressure nudging into 
the area from the west early this morning, isolated light rain 
showers or sprinkles were occurring over north-central WI aided by a 
500mb vort max overhead, with mostly cloudy skies occurring 
elsewhere. The cloud cover will limit any frost development from 
occurring this morning especially in far north-central WI where 
temperatures are most favorable.

Rain Chances...The surface high pressure is progged to reside over 
the area today into Friday, keeping dry weather in place for the 
remainder of the work week. Model guidance is suggesting the next 
chance for rain arrives Friday night into Saturday, as a southern 
stream system lifts across IL/IN/MI. This would leave the forecast 
area in the north/northwest precip shield of this system, minimizing 
the potential for any thunderstorms. However, the latest guidance is 
indicating the southern stream system may track further to the south 
and east, lowering the potential for precip in the area for Friday 
night into Saturday. Trailing behind this system is an upper-level 
trough/frontal passage that looks to bring another chance for rain 
sometime between Saturday night into Sunday, which may include the 
potential for thunderstorms. There are also signs of a shortwave 
moving over the area for Memorial Day, which could also bring rain 
and thunderstorm potential. Despite these features, the Memorial Day 
holiday weekend does not appear to be a washout, and more along the 
lines of periodic chances for showers and storms.

Temperatures/Frost Potential...Below normal temperatures are 
expected through Saturday, with today and Thursday being the cooler 
of the days with highs in the mid 50s to mid 60s. Given the cooler 
temperatures tonight (lows in the low to mid 30s across the 
Northwoods and upper 30s to low 40s elsewhere) and high pressure 
overhead, where clouds clear and winds become calm, anticipate frost 
development, mainly across the Northwoods. A Frost Advisory will 
likely be needed. High temps gradually warm into the 60s for Friday 
and Saturday before rising into the 70s for Sunday, and potentially 
into the 80s for early next week.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1225 AM CDT Wed May 20 2026

Low-end VFR clouds will remain across the area overnight, with a
few MVFR ceiling over far north-central WI. Downsloping northwest
winds will eventually help scatter out some of the clouds early 
Wednesday. Isolated sprinkles will continue overnight, mainly 
across north-central WI, but will have no impacts to aviation. 
Additional low-end VFR clouds are expected on Wednesday 
especially during the morning hours, with a few high-end MVFR 
ceilings possible in north-central WI. High clouds will also be in
the region, especially in the Wednesday afternoon/evening.

West/northwest winds will remain under 10 kts late this evening 
and overnight. Onshore flow near Lake Michigan could switch winds
to the east for a time overnight at GRB/MTW. North winds under 10
kts are expected on Wednesday, with a lake breeze shifting winds 
to the east across eastern WI in the afternoon.

&&

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

&&

$$

DISCUSSION.....KrukAVIATION.......Bersch