007 FXUS63 KMQT 201122 AFDMQTArea Forecast Discussion National Weather Service Marquette MI 722 AM EDT Sat Sep 20 2025
.KEY MESSAGES...
- Off and on showers and thunderstorms are expected through early next week.
- Seasonable temperatures continue through next week.
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.DISCUSSION... Issued at 443 AM EDT Sat Sep 20 2025
Early morning GOES WV imagery and RAP analysis highlight two features which will dominate the weather into early next week. The previously closed low has unraveled over MN and IA with its associated sfc low displaced to the NW over the E corner of the Dakotas at 1013 mb. The occluded front over W MN meets up with two stalled frontal boundaries over S WI and down into IA where better instability and resulting convection is ongoing on the radar mosaic. Upstream, two shortwave troughs are analyzed over Saskatchewan and MT with a weak ridge over the PAC NW. Temps will continue to hold in the 50s early this morning.
As the main deep trough continues to lift toward the UP and the upstream troughs approach the Upper MS Valley, the drier mid level air will be overridden and shra coverage will increase this morning. Instability and shear are both not expected to be impressive, but will be supportive enough for non-severe tsra, possibly gusting up to around 40 mph in stronger storms mainly over the S-Central. A lull in activity is anticipated this afternoon before the now warm front and stronger wave progress over the UP. This results in a more notable increase in shra/tsra coverage for tonight; strong to severe storms are not expected. Up to 0.25" of QPF is favored in the strongest storms with the first round; higher amounts between 0.25" and 0.75" is expected with stronger convection in the second round. Otherwise temps today peak in the mid 60s to low 70s, only settling into the mid to upper 50s tonight.
As the additional upstream shortwaves cycle through the region on Sun and Mon, further shra/tsra are expected. Instability will be higher, but the amount of wind shear available is still questionable. Regardless, severe weather is not expected. With ample low level moisture present (especially where precip occurs during the day) and calm winds overnight, patchy fog is expected Sun night and Mon night. From there, high pressure builds in from the N through Wed afternoon. Sct diurnal -shra are possible on Tue, but are not currently reflected in the fcst at this time. Confidence in the fcst breaks down Wed onward as models continue to struggle to resolve the closed low likely to develop. This initiates as a deeper trough making landfall on Sun over the PAC NW late today into Sun. This trough progresses over the Rockies on Mon then moves out over the Plains on Tue. From there it is uncertain how this wave will interact with the last lingering shortwave over the Upper Midwest and a ridge building over the NW CONUS. This will have implications on the sfc pattern and impact how dry the remaining portion of the week is. The latest run of the GFS quickly forms the closed low and keeps it along with its sfc low well within the region, yielding a much wetter solution compared to the ECMWF and Canadian. Those two models struggle to develop a closed low or keep the feature well to the S, leaving only slight chances for diurnal shra in the fcst early on. The NBM was left as is after Mon given the uncertainty, which favors dry weather until next weekend with a passing cold front. Otherwise, temps by and large stay consistent the entire fcst with highs in the mid 60s to low 70s and lows in the 40s and 50s.
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.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 722 AM EDT Sat Sep 20 2025
Abundant moisture continues to stream around an upper level low/trough moving into the Great Lakes region. This will support waves of rain showers, potentially mixed with thunderstorms, through this TAF period. At KIWD, MVFR ceilings are expected to largely prevail while KCMX and KSAW may deteriorate to at least MVFR this afternoon and evening as shower/thunderstorm activity moves near to these terminals. Wind gusts near 20kts will also be possible at KCMX into this afternoon. Overnight, current guidance suggest LIFR potential at KSAW.
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.MARINE... Issued at 443 AM EDT Sat Sep 20 2025
Easterly winds over the western third of the lake continue around 15- 20 kts with east to southeast winds between 20-30 kts over the remainder of the lake through this afternoon. This results in significant wave heights of 4-6 ft over the north central portion of the lake and along the international border waters today. Winds gradually settle below 20 kts from W to E through Sun morning, likely remaining below 20 kts through much of next week. Otherwise, expect on and off showers and thunderstorms this weekend.
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.MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None.
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DISCUSSION...Jablonski AVIATION...JTP MARINE...Jablonski
NWS MQT Office Area Forecast Discussion