NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 120402
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1102 PM CDT Sat Apr 11 2026

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Periods of heavy rainfall and thunderstorms expected from
  tonight through the middle of next week. There is a 80-100%
  probability of rainfall greater than 1 inch, and a 30-60%
  probability of greater than 2 inches.

- A round or two of strong to severe thunderstorms will be
  possible during the early to mid part of next week, with the
  best chances occurring late Monday afternoon and overnight,
  followed by additional chances Tuesday afternoon/evening and
  Wednesday afternoon.

- Much above normal temperatures expected, with highs in the 60s
  and 70s from Sunday through Friday.

- Minor flooding will continue along the Wolf River through the
  weekend. Combined runoff from melting snow in the Upper
  Peninsula and heavy rain will likely result in flooding on the
  Menominee River by Tuesday, with moderate to major flooding
  possible during the mid to late part of the week.

- More heavy rainfall and storms possible late in the week.

&&

.DISCUSSION...
Issued at 333 PM CDT Sat Apr 11 2026

An active weather pattern is expected during the next week with
multiple rounds of rain and thunderstorms. Some storms could be
strong to severe, and heavy rain could lead to flooding.

Activity starts late this afternoon as warm advection and 60kt LLJ
increase over the state. Already seeing showers to the west, and
expect the coverage of these to increase as rains also expands to
the east. Elevated instability of ~500-1500 J/kg will also bring
about scattered thunderstorms. Severe potential this evening and
overnight is generally low, but cannot rule out an isolated hail
threat, mainly in central WI.

Showers and thunderstorms continue throughout Sunday morning as
the surface warm front moves north across Wisconsin. Some
uncertainty on whether there is a break during the afternoon. Most
CAMs suggest yes as the warm front is north of the state;
however, if a storm does manage to develop there is a marginal
risk for it to become severe. Dew points surge into the 60s behind
the front, with CAPE of 1-2k J/kg. Precip potential then
decreases Sunday evening and overnight, with instability also
decreasing for a time.

Surface cold front moves south across northern WI on Monday, but
then stalls out and becomes a focus for redevelop Monday afternoon
through Tuesday, and possibly Wednesday. Specifics will come down
to exactly where the front stalls, but while in place on and off
opportunities for heavy rain and strong-severe storms will exist,
especially during the afternoons and evenings both Monday and
Tuesday while instability and lapse rates peak.

Throughout this time frame, milder temperatures are forecast with
highs in the 60s and 70s through Friday away from Lake Michigan.

For late week, another system looks to move across the Upper
Midwest once again bringing the potential for rain and
thunderstorms.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1101 PM CDT Sat Apr 11 2026

Clouds continue to slowly lower and thicken this evening with
widespread showers expanding across the region, as moisture
continues to increase and a LLJ increases. The rain showers will
continue late this evening, with a lull in the showers/storms in
the early morning hours of Sunday, with another round or two
Sunday morning, with most of the activity exiting by 18z Sunday.
Flying conditions will continue to deteriorate to MVFR/IFR late
this evening into early Sunday as the better moisture and heavier
rain showers arrives. Elevated thunderstorms are expected at time
as well. A few LIFR ceilings are possible Sunday morning.
Continued to use 2-4 hour TEMPO groups to highlight the most
likely timing for thunderstorms at each TAF site.

Southeast winds late this evening will shift back to the
southwest on Sunday. Gusts of 20 to 30 kts are forecast into
Sunday. LLWS is expected to continue through most of Sunday.

&&

.HYDROLOGY...
Issued at 333 PM CDT Sat Apr 11 2026

Minor flooding is expected to continue on the Wolf River through
at least early next week. Periods of heavy rain and thunderstorms
arrive tonight and continue through at least the middle of next
week. From tonight through Wednesday, probabilities for rainfall
in excess of 1 inch are 80-100%, with a 30-60% chance of amounts
in excess of 2 inches and a 5-20% chance of 3 inches or more.
Current forecasts call for 1.50 to 2.50 inches of rain in most
areas. Runoff from this rainfall, combined with rapid snowmelt in
the Upper Peninsula, is expected to bring river flooding on the
Menominee River by Tuesday, with moderate to major flooding
possible during the middle to late part of the week.

&&

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

&&

$$

DISCUSSION.....KLJ
AVIATION.......Bersch
HYDROLOGY......Kieckbusch/KLJ