FXUS63 KGRB 190324

AFDGRB



Area Forecast Discussion

National Weather Service Green Bay WI

1024 PM CDT Mon Aug 18 2025



Updated aviation portion for 06Z TAF issuance



.KEY MESSAGES...



- Showers will taper off this evening.



- Isolated showers are possible on Tuesday, with much of the week

  remaining dry. Friday will bring the next chance for area-wide

  showers and storms.



&&



.DISCUSSION...

Issued at 351 PM CDT Mon Aug 18 2025



This evening/Tonight...This afternoon's water vapor and radar 

imagery showed areas of rain moving northeast across the region 

associated with a 500mb vort max from a nearby shortwave. Additional 

shower activity was also developing in portions of central and east-

central WI, where a weak LLJ was located. The rain and shower 

activity is expected to continue through late this evening, ending 

from west to east. Still cannot rule out a few rumbles of thunder in 

central and east-central WI, where the greater instability (CAPE of 

500-1000 J/kg) is located. However, any heavier shower or 

thunderstorm will generate heavy rainfall with high rainfall rates 

(0.5 to 1"/hr) in central and east-central WI, as PWATs of 2-2.25 

inches will prevail through the evening. Localized flooding remains 

possible, mainly in low-lying and urban areas.



As the precip comes to an end, the recent rainfall and light winds 

will cause fog to develop late this evening through early Tuesday 

morning. Models indicate the potential for locally dense fog, mainly 

in central and north-central WI, but fog will be possible area-wide. 

A Dense Fog Advisory may be needed.



Tuesday...In the wake of the shortwave, northwest winds, CAA, and 

lingering low-level moisture will prevail across the region. Some 

models indicate isolated showers, with a few rumbles of thunder, 

developing in spots during the afternoon and evening, but impacts 

will be low.



Rest of the forecast...Surface high pressure will slide into the 

region from the northwest as upper-level ridging builds over the 

area. This pattern, bringing dry conditions and near normal temps, 

will prevail through at least early Friday before the next chance of 

showers and storms returns with a cold frontal passage sometime 

Friday into Saturday.



&&



.AVIATION...for 06Z TAF Issuance

Issued at 1017 PM CDT Mon Aug 18 2025



Showers will slowly pull out of far NE WI by TAF issuance. There

is a small chance of showers tomorrow afternoon, but will not 

mention in the TAFs at this point.



IFR/LIFR ceilings prevailed regionwide late this evening, and 

these will continue to gradually lower to LIFR (and perhaps 

VLIFR at RHI) overnight. Abundant moisture from recent rainfall, 

the arrival of high pressure, and light winds will result in 

widespread fog development away from Lake Michigan. Vsbys could 

drop as low as LIFR/VLIFR in NC/C WI, but should be mostly in the 

MVFR/IFR range near lake Michigan and the Fox Valley.



Conditions will steadily improve Tuesday morning, with most 

locations returning to VFR by early to mid afternoon.



Low stratus and patchy fog may return to northern WI toward the

end of the TAF period.



&&



.GRB WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



DISCUSSION.....Kruk

AVIATION.......Kieckbusch