Harris, Michigan Weather Forecast Discussion

099
FXUS63 KMQT 200843
AFDMQT
Area Forecast Discussion
National Weather Service Marquette MI
443 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.
&&
.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.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 109 AM EDT Sat Sep 20 2025
SAW and CMX have already made the transition from MVFR to VFR early
this morning, but IWD is still holding steady at MVFR. However, IWD
should also become prevailing VFR in the next few hours with a MVFR
tempo to then account for the next round of showers and isolated
thunderstorms expected to overspread Upper Michigan. PROB30 groups
have also been inserted at CMX and SAW throughout the TAF period to
capture periods of MVFR/IFR conditions in any heavier downpours.
Meanwhile, southeast winds will be an impact at CMX with gusts up
to 25 kts at times through the TAF period.
&&
.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.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
DISCUSSION...Jablonski
AVIATION...JTP
MARINE...Jablonski

NWS MQT Office Area Forecast Discussion