FXUS63 KGRB 261959

AFDGRB



Area Forecast Discussion

National Weather Service Green Bay WI

259 PM CDT Thu Jun 26 2025



Forecast discussion for routine afternoon forecast issuance



.KEY MESSAGES...



- There is a slight risk of severe thunderstorms in central Wisconsin

  and the southern Fox Valley late this afternoon and evening. 

  Damaging winds and a few tornadoes are possible. The greatest 

  threat is expected southwest of a line from Marshfield to 

  Oshkosh. Severe weather will be most likely between 4 pm and 10 

  pm.



- A Flood Watch has been issued for central Wisconsin and the

  southern Fox Valley, where soils are already saturated and 

  additional rainfall amounts of 1.5 to 3 inches are expected. 

  Areas with greatest flood potential include low-lying and urban 

  areas, though localized river flooding may also occur.



- Near/below temperatures continue through Friday, then increasing

  heat and humidity into the weekend, with highs near 90 by 

  Sunday.



- There is a chance of strong to severe storms late this weekend,

  especially Sunday afternoon and evening.



&&



.DISCUSSION...

Issued at 259 PM CDT Thu Jun 26 2025



Forecast concerns include severe weather and flooding potential

through this evening, and another couple rounds of strong to 

severe storms from Saturday night through Sunday evening.



Heavy Rainfall/Flooding Concerns: Will continue the Flood Watch 

for Wood, Portage, Waupaca, Waushara and Winnebago counties from

4 pm today through 4 am Friday. Much of this area has received 

1.5 to 3 inches of rain since Monday, so soils are saturated. A 

west to east line of storms extending from KLSE-KDLL-KUNU will

continue to lift north into our southern counties between 4-5 pm,

followed by a well-developed squall line crossing central and east

central WI from 6-10 pm. Both of these lines will be capable of 

producing torrential rainfall, given PWATs approaching 2 inches, 

and enough elevated instability to support higher rainfall rates 

with convection. The end time of the watch is likely longer than

it needs to be, as most of the heavier rain will be gone by late

evening, but wanted to match the end time of ARX's Flood Watch to

our southwest.



Severe Weather Threat Through This Evening: Most models keep the 

warm front and associated surface based instability south of the 

forecast area late this afternoon/evening, but given the close 

proximity of the front (shallow stable layer near the surface), 

MUCAPE of 500-1000 j/kg, deep layer shear of 40-45 kts, 0-3 km 

SRH of 200-300 m2/s2, there is potential for supercells with 

damaging winds and a few tornadoes, especially in our far 

southwest counties. CAMs show development starting in our far 

southwest by 4-5 pm. A squall line will also move through C/EC 

from west to east between 6 and 10 pm, with potential for sporadic

strong to damaging gusts.



Rest of the Forecast: Quieter conditions expected friday and

Saturday, with warmer temperatures in the 80s arriving for the 

weekend. A weak cold front is expected to approach the region 

Saturday night, then move through on Sunday and Sunday night, and 

this should bring a good chance of storms. With SBCAPE rising to 

2-4k j/kg on Sunday, there is ample instability to support severe 

storms. However, deep layer shear is on the weak side; around 

20-25 knots. Drier and more comfortable condiitons are expected

for much of the following work week.



&&



.AVIATION...for 18Z TAF Issuance

Issued at 1248 PM CDT Thu Jun 26 2025



Widespread IFR/MVFR stratus covered the forecast at issuance time.

Showers and embedded storms were approaching from MN, and these 

will impact our area during the late afternoon and evening.



Slight improvement (rising ceilings) will be observed at the TAF 

sites for the next couple hours, in advance of the rain. Once the

steady moderate to heavy rain arrives, expect IFR conditions to 

expand. After the rain tapers off later tonight, areas of fog and 

very low stratus (LIFR/local VLIFR) will become more widespread. 

Increasing west winds Friday morning will cause ceilings to 

gradually rise to MVFR by midday.



Have added thunderstorms to all TAF sites this evening, with the

exception of RHI. Torrential rainfall and gusty winds may

accompany any storms.



&&



.GRB WATCHES/WARNINGS/ADVISORIES...

Flood Watch through late tonight for WIZ035>037-045-048.

&&



$$



DISCUSSION.....Kieckbusch

AVIATION.......Kieckbusch

