822
FXUS63 KMQT 101129
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
729 AM EDT Thu Jul 10 2025

.KEY MESSAGES...

- Chances for showers and thunderstorms return Friday and
  Saturday. Otherwise, a mostly dry end of week is expected.

- Seasonable temperatures persist in the Upper Peninsula for
  the work week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 347 AM EDT Thu Jul 10 2025

GOES-East imagery shows a remarkably clear night over the UP, though
high clouds upstream are advancing towards the region and are
expected to reach the western UP and expand through the west half of
the UP throughout the morning hours. Aloft, RAP analysis 500mb
charts show the UP remaining upstream of a ridge axis centered over
northern Ontario, but a prominent shortwave to the south of it is
the cause of disturbed weather upstream (and thus explains the
aforementioned high cloud cover). Besides a couple of CAMs showing
the line of convection ongoing in Minnesota reaching the far western
open waters of Lake Superior from 16-20Z today, model guidance
consistently shows upstream convection either petering out entirely
by the time it reaches the UP or skirting around the UP, primarily
to the south. This is due to the high surface pressure upstream of
the aforementioned ridge aloft, which the RAP analysis shows at
1016mb currently and the 00Z GEFS only shows modestly weakening
throughout today. Sustained high pressure will help temperatures
trend warmer today relative to yesterday, with high temps around the
80 degree mark expected. Once exception will be in the immediate
vicinity of the Great Lakes, where CAMs show prominent lake breezes
today, and the marine layer will help keep the shorelines in the mid
to lower 70s for highs today.

Expect tonight`s overnight lows to also trend warmer (around the 60
degree mark) especially as increasing cloud coverage decreases the
efficiency of radiational cooling. Chances of precipitation tonight
have trended downwards, but have left some slight chances (15-25
percent) of showers and thunderstorms along the state line to cover
some of the faster solutions that still remain in the ensembles in
bringing pre-warm frontal precipitation to the area Friday.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 225 PM EDT Wed Jul 9 2025

Beginning Friday, mid-upper ridge axis will lay through Upper
Michigan, with a series of shortwaves embedded within split stream
flow stream upstream over the Central and Northern Plains. Various
placement of previous night MCVs are apparent in the different
deterministic packages, which supports my initial uncertainty in the
timing of the key features for Upper Michigan. Although 12z guidance
appears to have produced a better consensus which overall looks
to pull a warm front or the attendant surface low through the
forecast area Friday afternoon or overnight. This while the mid-
level shortwave to the west moves from the Dakotas into
Minnesota/western Lake Superior. This main shortwave begins to
take on a negative tilt, which might absorb the original
low/shortwave. 6z and 12z guidance is unclear if this will
actually take place overhead or downstream in northern Ontario.
Regardless though, the cold front will help push the surface low
through the region Saturday and Saturday night. While questions
of the timing and location of the initial features exists,
showers, potentially mixed with thunderstorms should be
expected. Given the temporal clarity of the initial timing of
precip, instability/shear may be present over the region, which
could support stronger storms late Friday. DCAPE values suggest
an isolated strong to severe wind threat, but model soundings
show light background winds upwards of 25k ft, suggesting this
potential is low (<25%). Guidance also suggests potential for
mid-level lapse rates increasing to ~7C/km, which may be enough
to support hail should a stronger updraft get going. Showers and
storms will press through the region overnight while the cold
front moves in from the west. Given the questions about phasing
and the timing of the initial showers/storms, its unclear if
precip will occur all day Saturday, or be mainly limited to the
afternoon/evening hours ahead of the front.

From there, another shortwave migrates through the region Sunday
evening and overnight while surface high shifts from the Upper
Midwest to the Lower Great Lakes. The high looks to keep the region
mostly dry Sunday, but a line of showers may accompany the wave late
Sunday night/Monday morning. A deep trough moving through the
Canadian Prairies and a shortwave lifting northeast from the Central
Plains will shift toward Upper Michigan on Monday. There are notable
timing differences in the model suites regarding these and whether
or not they`ll phase overhead next week. Right now the main window
for precip associated with these features focuses on Tuesday to
Wednesday. Daytime highs each day look to climb into the 70s to mid
80s and with overnight lows dipping into the 50s and 60s.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 729 AM EDT Thu Jul 10 2025

VFR conditions are expected to prevail throughout this TAF period
under high pressure. Expect primarily light winds mainly out of the
south at IWD and SAW, though CMX will have some varying winds
throughout the period, and a Lake Superior lake breeze could
make for variable wind directions at times at all sites. Friday,
-SHRA and -TSRA will eventually impact all terminals, but
currently chances of precip (and thunder) are 15-30% only at IWD
prior to 12Z. Cloud heights in the MVFR range would accompany
such showers, but it is uncertain whether enough coverage would
be present to make for BKN skies.

&&

.MARINE...
Issued at 225 PM EDT Wed Jul 9 2025

Winds generally remain generally ~15 kts or less through the
remainder of the work week as weak high pressure traverses the Great
Lakes. However, a couple of disturbances move through the region
Friday into the weekend. Thus, we can expect showers and
thunderstorms to form from west to east across the lake from Friday
through Saturday. In addition, we could see winds increase to around
15-20 knots from the southwest on Saturday, persisting into Sunday
before falling back into Monday. Expect a brief reprieve from
convection Sunday before additional storms potentially move in with
a Clipper system next Sunday night through Monday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...GS
LONG TERM...JTP
AVIATION...GS
MARINE...LC