786
FXUS63 KMQT 051134
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
734 AM EDT Sat Jul 5 2025

.KEY MESSAGES...

- Hot and humid conditions persist through this evening. Please
  practice necessary heat safety measures if you plan on
  participating in outdoor holiday weekend festivities.

- Showers and thunderstorms move from west to east this
  afternoon into Sunday morning. Heavy downpours and lightning
  should be expected in these storms. Some storms could be
  strong to severe.

- Stronger winds on the Great Lakes will result in dangerous
  swimming conditions in Schoolcraft County tonight and Sunday
  in Alger and Luce counties.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 350 AM EDT Sat Jul 5 2025

Early morning GOES satellite imagery and RAP mesoanalysis reveal
Upper Michigan placed on the backside of a positively tilted upper
ridge extending east of the Upper Great Lakes. Upstream, troughing
just west of the Hudson Bay extends southward with an embedded
shortwave working into the High Plains and western MN. At the
surface, low pressure in N Ontario dips south into the MN/Dakotas
border as the weaker embedded wave reflects a wave sfc trough near
1008 mb. A cold front stretches along the same axis. Ahead of this
boundary, warm and moist SW flow is aiding in shower and
thunderstorms development across much of MN, currently reaching far
western Lake Superior. Temps across da Yoop have not been able to
cool much tonight as much of the western UP remains in the mid to
upper 70s (81 at CMX as of 3AM), only slighting dropping to the
upper 60s in the far east.

Luckily, relief from the heat and humidity is on the way, but we
will have to endure one more hot and humid afternoon. The
aforementioned upstream troughing and sfc cold front will slowly
meander east across the Upper Great Lakes this afternoon and
evening. Ahead of the front, warm and moist southerly flow will
allow temps to climb into the upper 80s across the central and
eastern UP, which coupled with dewpoints near 70 results in heat
indices reaching the low 90s. Those participating in outdoor holiday
weekend events should continue practicing heat safety measures.
Showers and thunderstorms ahead of the front will be knocking on the
far western UP`s door by ~12z this morning before pressing into the
central counties ~18z, and eventually crossing into the eastern
third by 00z at the latest. Any organized thunderstorms could be
strong to severe as bulk shear reaches ~25-35 kts and available
instability climbs upwards of 1500-2000 j/kg. The biggest concern,
however, will be flash flooding. Anomalous moisture characterized by
PWATs near or exceeding 2" (in the 99th to Max of NAEFS PWAT
climatology), long skinny CAPE profiles noted in model soundings,
deep warm cloud layer >10k ft, and slow Corfidi vectors 5-15 kts all
point towards more hydro / flash flooding concerns. Storms will be
efficient rainfall producers, potentially dropping 2-3" where
training occurs. This is highlighted well by the latest 00z HREF
where 3hr PMM QPF values across the greater central UP exceed 2"
this evening.

Those with outdoor plans this afternoon and evening should stay
weather aware just in case precipitation or severe weather impacts
their plans. The system slowly inches through the region overnight,
with lingering precip across the east half Sunday morning.

Cooler overnight lows are expected behind the frontal passage,
generally falling to the 50s across the northern tier to low 60s
south.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Issued at 229 PM EDT Fri Jul 4 2025

Beginning Sunday, near zonal flow stretching across the Northern
Tier will be interrupted by a couple shortwaves. The first will move
through Upper Michigan Monday while high pressure at the surface
keeps the region mostly dry. The second follows Monday night into
Tuesday evening, potentially overlapping with a slowly moving frontal
boundary, which may support precipitation. Some deterministic
solutions suggest another wave may dip down into the region
Wednesday in the lee of upper level ridging across the Northern
Plains and central Canada. Afterwards, notable differences in
deterministic guidance packages in regards to the timing of the
eastward progression of the upstream ridge. This impacts the timing
and position of a closed upper level low dipping through Ontario,
perhaps into the Upper Great Lakes Thursday and the next system
dropping southeast out of the Canadian Rockies. Overall, this
provides for shower and thunderstorm potential, to some degree, most
days in this forecast period, with the best chances on Tuesday (20-
50%). At the moment, notable severe weather signals are not present,
or at least there isn`t a consensus on any of these signals. Daytime
temperatures look to peak in the upper 60s to upper 70s on Sunday,
then the upper 70s to low 80s away from Lake Superior and upper 60s
to low 70s by Lake Superior each day thereafter. Overnight lows look
to fall into the 50s most days, except low 60s in southern Menominee
County and perhaps, some high 40s Sunday night in the interior.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 733 AM EDT Sat Jul 5 2025

VFR conditions start out the day before showers and storms impact
all sites, lowering cigs/vis through the rest of the day into Sunday.
Showers arrive at all sites in the morning to early afternoon hours,
with TSRA chances ramping up at all sites in the afternoon. With the
precip will come lowered ceilings and thus lowered flight
categories. IWD falls to MVFR by 15Z and up to 25% chances of IFR or
lower in the afternoon. CMX is expected to fall to MVFR around 18Z
but could as soon as 15Z if the terminal experiences a heavier
thundershower, with conditions approaching IFR around 21Z. SAW will
see MVFR ceilings around 22Z with IFR expected after 00Z. Expect
gusty winds out of the southwest until a cold front pushes through
around 00Z, veering winds to be out of the northwest.

&&

.MARINE...
Issued at 350 AM EDT Sat Jul 5 2025

Elevated S to SW winds 20-25 kts are expected to persist today
before veering NW late along a cold front. Additionally, this
frontal boundary may produce strong thunderstorms which may
bring erratic winds, lightning, and small hail. Strong N to NW
winds will follow the front late tonight into Sunday, with gusts
generally up to 20-25kts. Winds fall back into early next week.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement from 4 PM EDT this afternoon through
     late tonight for MIZ014.

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

&&

$$

SHORT TERM...BW
LONG TERM...JTP
AVIATION...BW
MARINE...BW/LC