971 FXUS63 KDLH 051910 CCA AFDDLHArea Forecast Discussion...CORRECTED National Weather Service Duluth MN 210 PM CDT Fri Sep 5 2025
.KEY MESSAGES...
- Gale Warning for portions of western Lake Superior through tonight.
- Frost Advisory tonight into Saturday morning for portions of northeast Minnesota, including the Arrowhead, Iron Range and Borderlands areas.
- Continued cool on Saturday with scattered rain showers and a few embedded thunderstorms.
- Frost will be a concern on Saturday and Sunday nights before temperatures warm next week.
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.DISCUSSION... Issued at 121 PM CDT Fri Sep 5 2025
Issued a Frost Advisory for tonight into Saturday morning for portions of northeast Minnesota, including the Arrowhead, Iron Range and Borderlands areas, namely inland Lake and Cook counties, northern and central St. Louis county, Koochiching and northern Itasca counties. Given what will be a very cool start to the evening, frost is likely for the above areas with light winds with a reduced pressure gradient and clearing skies as wrap around moisture pushes east through the evening and night. Some mid level cloud cover is expected through the night, however, the cool start to the evening should make low temperatures in the lower to mid 30s very achievable. Elsewhere across northeast Minnesota and northwest Wisconsin, the frost threat is not zero, and will be largely dependent on how fast winds and clouds decrease this evening. An expansion of the Frost Advisory is not out of the question.
Furthermore, there is also a non-zero chance for a few snowflakes from fading rain showers near sunset this evening.
Another cool day is forecast on Saturday across the Northland with cyclonic flow aloft, and one more stronger embedded shortwave that will support another round of scattered rain showers. A bit more instability will be in place on Saturday, so a few non- severe thunderstorms are possible with peak daytime heating. High temperatures on Saturday will be in the upper 50s to the lower 60s, which are above record low max temperatures for Saturday. Frost will also be possible Saturday and Sunday nights potentially across a larger portion of northeast Minnesota and northwest Wisconsin, but, will be dependent on cloud cover.
Cyclonic flow aloft will become more zonal Monday into Tuesday marking a moderation in temperatures back to near normal in the upper 60s and lower 70s. This will also temporarily reduce the overnight frost threat as well. The timing and amplitude of the shortwave on Tuesday, and its associated rain shower and thunderstorm threat, has some differences across the global ensemble suites to sort out over the next few days.
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.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 121 PM CDT Fri Sep 5 2025
MVFR conditions in stratus and scattered rain showers will continue across most of northwest Wisconsin and northeast Minnesota this afternoon and evening, slowly clearing from northwest to southeast this evening and into the overnight. Northwest wind gusts of 25-30kts will also continue through sunset. Patchy fog is possible, a 20-25 percent chance, late tonight into early Saturday morning across the area. However, confidence is too low to include in the TAFs at this time. VFR conditions are forecast on Saturday with cumulus fields and scattered rain showers a few thunderstorms with peak daytime heating.
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.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 930 AM CDT Fri Sep 5 2025
Upgraded to a Gale Warning from Port Wing to Sand Island and for the Outer Apostle Islands today and tonight for northwest wind gusts to 35 kts and waves of 4 to 8 feet. Elsewhere, a Small Craft Advisory remains in effect today and into tonight for wind gusts of 25 to 30 kts, and waves of 1 to 3 feet along the North Shore and 2 to 5 feet for areas not in the Gale Warning on the South Shore. There is a 30 to 40 percent chance of Gale Force wind gusts of 35 to 40kts along the North Shore this afternoon and evening, especially from Taconite Harbor to Grand Marais to Grand Portage, with stronger winds off of the terrain.
For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.
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.DLH WATCHES/WARNINGS/ADVISORIES... MN...Frost Advisory from 1 AM to 9 AM CDT Saturday for MNZ010>012- 018-019. WI...None. MARINE...Small Craft Advisory until 5 AM CDT Saturday for LSZ121-140- 141-147-148. Small Craft Advisory until 1 AM CDT Saturday for LSZ142>145. Gale Warning until 5 AM CDT Saturday for LSZ146-150.
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DISCUSSION...PA AVIATION...PA MARINE...PA
NWS DLH Office Area Forecast Discussion