720 FXUS63 KGRB 061917 AFDGRBArea Forecast Discussion National Weather Service Green Bay WI 217 PM CDT Sat Sep 6 2025
Forecast discussion for routine afternoon forecast issuance
.KEY MESSAGES...
- Isolated to scattered showers expected through this evening.
- Frost potential Monday morning. Temperatures warming next week, but remaining below normal.
- Chances for rain and a few storms Monday night into Tuesday night.
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.DISCUSSION... Issued at 217 PM CDT Sat Sep 6 2025
A mid level shortwave will track through Wisconsin through this evening, which will bring isolated to scattered showers as it moves through during peak heating. While there is a non-zero chance for thunder, the chance will be fairly low as SBCAPE values are at best 100 to 200 J/kg. This activity should dissipate later in the evening with the loss of daytime heating as the shortwave tracks off to the east. Some showers may linger across far northern Wisconsin a bit later as the region will still be in cyclonic flow with some moisture from Lake Superior across that part of the area. Temperatures tonight could fall into the upper 30s across portions of central and north-central Wisconsin tonight with some very patchy frost possible; however, there will still be some clouds around and winds are not expected to completely die off. Therefore, any frost is not expected to be widespread nor a high impact.
High pressure will build in across the area on Sunday, which will keep the area dry. Some sunshine will allow daytime temperatures to rise a few degrees higher than today, some some afternoon cumulus clouds expected to develop during the afternoon. Mostly clear skies and light winds will allow temperatures to plummet Sunday night into Monday morning, as lows will generally be in the middle to upper 30s north and west of the Fox Valley with the coldest temperatures across north-central Wisconsin. A Frost Advisory may be needed in subsequent forecasts due to the widespread nature of the frost and higher impact.
The high will push east on Monday, allowing for warmer air to advect in as surface winds turn southwesterly. Highs on Monday are expected to recover into the upper 60s to lower 70s. An approaching cold front will bring the next chance for showers and thunderstorms as it tracks through the area Monday night through Tuesday night. Thunderstorms will be possible with modest MUCAPEs of a few hundred J/kg, but severe weather is not anticipated at this time. High pressure will then keep the weather dry and warmer for the middle to late part of next week.
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.AVIATION...for 18Z TAF Issuance Issued at 1159 AM CDT Sat Sep 6 2025
SCT-BKN stratocu will prevail through early this evening due to diurnal heating. CIGs should mainly be VFR; however, some MVFR CIGs will be possible at time, especially near the MI border. ISOL-SCT showers are expected this afternoon into early this evening and will stick with the PROB30 due to the uncertainty of them reaching the TAF sites. The showers and stratocu are expected to dissipate this evening after sunset, with some clearing expected.
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.GRB WATCHES/WARNINGS/ADVISORIES... None.
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DISCUSSION.....Kurimski AVIATION.......Kurimski
NWS GRB Office Area Forecast Discussion