786
FXUS63 KMQT 121707
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
107 PM EDT Sat Jul 12 2025

.KEY MESSAGES...

- A Marginal Risk (category 1 of 5) of severe thunderstorms is in
place for the UP today with damaging winds and hail possible (5-15%)
as a warm front lifts north and a cold front pushes east.

- A Marginal Risk (category 1 of 4) of excessive rainfall is in
place for the UP today as rainfall totals over an inch may be seen,
especially in the eastern UP (40-80% chance).

- Some hazy/smoky skies expected behind the cold front this evening
as wildfire smoke from Canada is pushed towards the UP.

- Next chances for thunderstorms look to be with a cold front in the
Tuesday/Wednesday timeframe.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 416 AM EDT Sat Jul 12 2025

KMQT radar returns are showing two primary areas of precipitation
this early morning: a thin line of showers over the western UP and a
broad shield of showers across much of the eastern 2/3 of the UP.
The latter precip looks to be forced isentropically ahead of a
lifting warm front while the former is along a stalled cold front.
Model soundings do show steep midlevel lapse rates in the western UP
supporting up to 1000 J/kg of MUCAPE, however, flow is largely very
weak with sub-15 kt flow up to 400 mb, so despite some 50+ dBZ
returns being shown, much of the shower activity is quite
disorganized and not moving particularly fast. Should stronger
showers continue to remain for the next few hours while not moving
much, some attention will need to be given to hydrologic concerns as
the Porcupine Mountains in particular saw nearly 2 inches of rain
yesterday. Rainfall rates with the pre-warm frontal precip are much
lighter with MRMS suggesting around 0.05"/hr rates. Neither area of
precipitation has produced lightning yet, though LightningCast has
occasionally lit up with some 10+% threats of lightning with the
western showers.

Throughout this morning, flow aloft perpendicular to the cold front
will increase, allowing for the front to progress from west to east.
Meanwhile, the eastern UP will see some robust 850mb frontogenesis
which will support more robust shower activity with some embedded
thunderstorms. Whether either forcing mechanism will have enough
shear and instability to force strong to severe thunderstorms is
uncertain with each of the CAMs showing different coverage and
intensities of storms in the morning hours, but generally severe
weather is not expected as despite the increase in flow, shear is
not expected to have increased enough to keep storms organized as
well as it being too early for proper surface-based destabilization
to occur. Most CAMs do show a lull period around noon today as the
warm frontal shield lifts out of the eastern UP and convection
settles down in the western UP. This afternoon, as diurnal heating
allows for SBCAPE to climb to near 1000+ J/kg, the HRRR and NAMNest
do show robust convection reforming along the cold front in the
central UP. Should that occur, a marginal severe threat could be
realized, though much of the other CAMs show much more reserved
showers redeveloping, perhaps owing to paltry 0-3km SRH values
in the sub-50 range keeping things disorganized. Some attention
will need to be paid to the flooding potential in the east today
as HREF LPMM plots show the potential for 1-3+ inches of rain
to accumulate if embedded stronger showers in the warm frontal
zone are followed by more robust convection in the afternoon,
though the terrain and geology of the eastern UP makes it not as
prone to flash flooding as the western UP, and given training
is not expected with the second round, flooding concerns remain
marginal, though non-zero.

Besides the rain/thunder, expect high temperatures in the 70s today.
Air quality will be worth watching in the wake of the cold front as
prevailing winds shift to put the UP downstream of the northwest
Ontario/Manitoba wildfires with the post-frontal subsidence
pushing some of the smoke into the lower layers of the
atmosphere. Of particular note is the RAP-Smoke and HRRR-Smoke
resolving 35+ ug/m3 of near-surface smoke concentration, which
if it were to occur would push the air quality to levels
generally unhealthy for sensitive groups. Low temperatures look
to cool to around the 60 degree mark tonight as precip exits to
the east by 05Z Sunday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 326 PM EDT Fri Jul 11 2025

The extended period starts off with quiet and generally dry weather
Sunday into Monday with surface ridging behind the exiting cold
front. However, a weak midlevel shortwave moving through later
Sunday may bring an increase in cloud cover, and some spotty rain
showers are not totally out of the question. Temperatures come in
slightly warmer, peaking in the lower/mid 80s both days across most
of the UP.

By early Tuesday, split flow sets up over the CONUS with mainly
zonal flow over the northern tier and sprawling ridging to the
south. Guidance is in agreement on broader troughing dropping from
the northern Prairie provinces into Ontario, and another, tighter
wave moving through British Columbia. There is also general
agreement on either a broad surface low or trough developing either
over Ontario or the Great Lakes, dragging a cold front through the
UP and bringing our next chances for showers/storms Tuesday into
WEdnesday, though differences in timing and strength persist among
guidance. After another brief period of ridging behind the front
Wednesday, the aforementioned western shortwave moves towards the
Great Lakes late next week, with another round of PoPs on the way.

After next week`s cold front, daytime highs look to climb only into
the upper 60s to near 70 Wednesday onwards. Overnight lows are
largely expected to be in the 50s and 60s, with potential for may
interior locations to cool into the low to mid 40s behind next
week`s front.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 107 PM EDT Sat Jul 12 2025

Main aviation hazards in the 18Z cycle are IFR/LIFR cigs early in
the TAF period, potential for thunderstorms mainly at SAW this
afternoon, and areas of wildfire smoke reducing visibility this
afternoon through the end of the TAF period. IFR/LIFR cigs are
around as of 17Z, but these should lift to at least MVFR levels by
18-19Z as diurnal heating helps to mix the atmosphere. A line of
showers with an embedded storm or two along a frontal boundary
should reach near SAW near the start of the TAF period at 18Z;
PROB30 included for TS potential 18-19Z. Another round of storms is
possible in the 20-22Z frame; TEMPOs included for this. Finally,
wildfire smoke is already reducing vsby behind the front, with
widespread 1-4SM vsby noted over the western UP and northern MN.
Kept vsby in the MVFR range for now but could see some IFR vsby as
well; will continue to monitor. Westerly wind gusts to 20 kt will
continue at CMX for most of the period.

&&

.MARINE...
Issued at 326 PM EDT Fri Jul 11 2025

Winds generally remain below 15kts through tonight into early
Saturday. However, winds turning over to the WSW increase to around
20kts across the western half of the lake late Saturday with a
passing cold front. Winds remain elevated through Sunday before
falling back below 15kts Monday, then increase to around 15kts out
of the southeast Tuesday. This will coincide with some disturbances
moving through the Great Lakes Region over the weekend. With these
disturbances, showers and thunderstorms will overspread the lake
from west to east late tonight through Saturday. Further out,
additional shower and thunderstorm chances will accompany a Clipper
system late Monday through Tuesday. Also of note, patchy fog could
result in reduced visibilities across far western portions of the
lake tonight if we can pick up on any precipitation.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Air Quality Alert until noon EDT /11 AM CDT/ Monday for
     MIZ001>005-009>011-084.

  Air Quality Alert from midnight EDT /11 PM CDT/ tonight to
     noon EDT /11 AM CDT/ Monday for MIZ006-007-012>014-085.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

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