140
FXUS63 KGRB 111747
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1247 PM CDT Sat Jul 11 2026

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Isolated thunderstorms are possible this afternoon across north-
  central and far northeast WI. Severe weather is not expected.

- Thunderstorms are possible across the north Sunday afternoon. A
  few strong or severe storms are possible.

- Building heat and humidity early next week will bring a period
  of heat-related impacts, with heat index values forecast to rise
  into the middle 90s to around 100F on Monday and Tuesday.

&&

.DISCUSSION...
Issued at 206 AM CDT Sat Jul 11 2026

A repeat of yesterday afternoon with isolated showers and storms
across north-central and far northeast WI. Highs will be in the
80s. Tranquil conditions expected Saturday night. Meanwhile on
Sunday, there is a chance of thunderstorms during the afternoon
across the north. The latest Day 2 Outlook from SPC has a Marginal
Risk over much of northeast WI. 0-6 km shear and enough CAPE to
bring the potential for a strong/severe storms. Still a lot of
uncertainty if/when convection breaks out and if its expands
across the area. Later shifts may need to expand chances of storms
into Sunday night.

Temperatures will continue to warm over the weekend as 850mb temps
climb to +22C to +24C on Monday. High temperatures will reach
into the 90s at most places on Monday and Tuesday. The warmest
850mb temperatures are across the north, thus some of the warmest
temperatures may be found up towards Marinette and Iron Mountain.
The latest MET/MAV guidance at Iron Mountain indicated 100 on
Monday. These values will probably be close to what portions of
northern Marinette County will see, especially at our typical hot
spots. The latest guidance values indicated dewpoints in the 60s
to around 70. These values combined with air temps in the 90s
support heat index values of middle 90s to around 100F. A degree
or two difference in dewpoint temperatures could make a difference
Heat related headlines.

The latest numerical guidance for Wednesday would support another
hot day. High temperatures will likely go up a few degrees in the
coming days. Beyond Wednesday, the details are murky when the
next chance of storms arrive across the area, but the latest
model run would indicate Friday, compared to Thursday yesterday.
Temperatures should trend slightly downward late in the week, but
remain well above normal.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1247 PM CDT Sat Jul 11 2026

VFR conditions are expected through this TAF period. A FEW/SCT cu
field developed over central and north-central WI early this
afternoon with cloud bases of 3500-5000 ft AGL, while clear skies
prevailed elsewhere. Anticipate the cu field to stick around
through early this evening. A couple showers with a possible
isolated storm will pop up within the cu field, mainly across
north-central WI this afternoon. Included a PROB30 group for the
shower potential at RHI, where confidence is highest.

Otherwise, clear skies and light winds, mainly up to 5 kts are
expected through Sunday morning. Winds turn southwest Sunday
morning and increase to around 10 kts, with gusts to 15 kts across
the far north. A few isolated showers and storms are possible
again Sunday afternoon across the north, which may become strong
or severe.

&&

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

&&

$$

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

NWS GRB Office Area Forecast Discussion