755
FXUS63 KGRB 211143
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
643 AM CDT Thu May 21 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- A Frost Advisory and Freeze Warning remain in effect across
  northern Wisconsin through 8 AM this morning, where
  temperatures as low as 30 degrees are expected. A Frost Advisory
  is also in effect for Door County.

- Below normal temperatures continue throughout the week, warming
  to above normal late this Memorial Day weekend into early next
  week.

- Dry weather is expected through at least Friday afternoon with
  periodic rain chances throughout the Memorial Day weekend.

&&

.DISCUSSION...
Issued at 313 AM CDT Thu May 21 2026

This morning`s RAP analysis indicated a surface high pressure was
centered over Lake Superior/Upper MI, bringing mostly clear skies
and calm/light winds to much of northern WI. These conditions aided
in surface temps dropping into the low 30s along the WI/Upper MI
border, but mid-level clouds were keeping temperatures across
central and east-central WI in the low to mid 40s. Therefore, the
current Frost Advisory in effect for the Northwoods until 8 AM
remains on track. Considered upgrading counties along the WI/Upper
MI border to a Freeze Warning, but the amount of time below freezing
is expected to be too brief or too localized.

Rain Chances...Due to the proximity of the surface high pressure,
dry conditions with periods of mid-level clouds are expected to
continue today through at least Friday afternoon. Model guidance is
still indicating two systems will approach the region for the start
of the Memorial Day weekend, one from the south and one from the
west. The latest guidance would suggest only a portion of eastern WI
may get clipped by the northwest precip shield of the southern
stream system late Friday night into Saturday, while portions of
central and north-central WI could see light precip from the other
system on Saturday and perhaps Sunday, but forcing appears weak.
Additional weak shortwaves look to bring chances for showers and
storms at times through the middle of next week as well.

Temperatures...Another cooler day is expected for today with high
temperatures about 10-15 degrees below normal ranging from the
mid 50s to low 60s. Lows tonight are expected to be chilly again
ranging from the mid 30s across the Northwoods to low 40s south.
The potential for frost development across the Northwoods tonight
is low at this time due to anticipated cloud cover. Temperatures
will gradually warm each day through the Memorial Day weekend,
rising above normal by Sunday with highs in the 70s. Upper- level
ridging and southerly flow looks to bring temps into the 80s for
Memorial Day through at least midweek.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 642 AM CDT Thu May 21 2026

Good flying conditions are expected through this TAF period with
mid-high VFR clouds prevailing. There is a very low chance of a
stray sprinkle across central and east-central WI this afternoon,
but dry air in the low-levels should limit this activity.
Southeast to east winds are expected throughout this TAF period,
mainly under 10 kts.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM CDT this morning for WIZ005-010-
018>022-073-074.

Freeze Warning until 8 AM CDT this morning for WIZ011>013.
&&

$$

DISCUSSION.....Kruk
AVIATION.......Kruk

NWS GRB Office Area Forecast Discussion