NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 081730
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1230 PM CDT Wed Apr 8 2026

Forecast discussion for routine afternoon forecast issuance

.KEY MESSAGES...

- Potential for heavy rainfall and thunderstorms this weekend into
  early next week. 1 to 1.5" of QPF expected, with up to 2"
  possible in spots. Strong or severe thunderstorms then possible
  Monday into Tuesday.

- Gale Warning remains in effect on Lake Michigan through this
  evening.

- Minor flooding continues along a few rivers, though runoff from
  melting snow in the Upper Peninsula paired with heavy rain may
  result in more widespread and significant flooding this weekend
  into early next week.

&&

.DISCUSSION...
Issued at 958 AM CDT Wed Apr 8 2026

Radar shows any remnants of the wintry mix from this morning
departing the area to the east as of early this afternoon.
However, we will only be afforded a brief dry spell before better
saturation returns late this afternoon into this evening with the
passage of a potent mid-level shortwave and tandem cold front.
This should bring an additional 0.25 to 0.5" of QPF across the
forecast area through Thursday morning. Narrow corridor of
elevated instability (200 to 300 J/kg) right along the front
would suggest that a rumble or two of thunder wouldn't be out of
the question this evening, though no organized storms are
expected.

Transient shortwave energy paired with mid-level FGEN will bring
another quick-hitting round of light rain to northeast Wisconsin
Thursday night into Friday morning. Most areas should see under a
tenth of QPF, with highest amounts approaching 0.2" over east-
central Wisconsin.

Weekend rain/storm chances... Prevailing southerly flow and a
wide open Gulf will promote a period of prolonged active weather
through next week. Of particular concern will be the Monday into
Tuesday period as a deepening surface low and attendant cold
front track through the upper Mississippi Valley. PWATs ranging
from 1 to 1.25" would support a decent period of moderate to heavy
rain during this time, with probabilistic guidance showing a 10
to 30% chance for receiving 1.5" of QPF through Tuesday morning.
Modest instability (~1,000 to 1,200 J/kg MUCAPE) and appreciable
deep layer shear (45 to 55 knots) may result in the development of
strong or even severe storms late Monday into Tuesday, though
there are still timing discrepancies within the ensembles
regarding cold FROPA. This would likely make a difference in
whether or not surface-based storms would be able to develop, and
is worth monitoring in the coming days. Regardless, CSU and NCAR
machine learning algorithms highlight much of the upper Midwest in
a 15 to 30% prob severe out to Day 6.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 958 AM CDT Wed Apr 8 2026

Flying conditions improved to VFR across all terminals early this
afternoon as any remnants from this morning's wintry mix departed
to the east. However, moderate to heavy rain will return later
this afternoon and this evening, bringing lowering and thickening
MVFR cigs with it. Vsbys may also briefly drop to MVFR within
heavier rain. A rumble or two of thunder wouldn't be out of the
question later this afternoon and evening, though would be
isolated enough to warrant omission from the TAFs. Conditions
should then improve to VFR in the wake of the rain, though lower
cigs may persist in/around RHI.

LLWS concerns persist through the beginning of the TAF period as a
50 to 60 knot 850 mb jet exits to the northeast. Otherwise, gusty
southerly winds continue at the surface through this afternoon,
with gusts to 30 knots possible at most sites. Winds then subside
and veer to westerly Thursday morning.

&&

.HYDROLOGY...
Issued at 958 AM CDT Wed Apr 8 2026

Minor flooding continues on the Wolf River, persisting for the
better part of the next week. Fast flows and bankfull conditions
were observed elsewhere, namely on the Oconto, Menominee, and
Wisconsin rivers. Moving forward, active pattern with ample
moisture supply will continue to result in hydro concerns for the
foreseeable future, especially with PWATs nearing absolute max
relative to climo with the passage of another system this
weekend. Probabilities for receiving 1.5" of QPF currently range
from 10 to 30% during this time, which would only exacerbate soil
saturation and promote runoff. Convectively-enhanced rainfall
would also support river/stream rises early next week. Area of
particular concern looks to be the Menominee River and its
tributaries, where a signal for minor and even moderate flooding
exists due to the additional influence of snowmelt from the Upper
Peninsula.

&&

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

&&

$$

DISCUSSION.....Goodin
AVIATION.......Goodin
HYDROLOGY......Goodin