550
FXUS63 KMQT 011147
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
747 AM EDT Tue Jul 1 2025

.KEY MESSAGES...

- Near to above normal temperatures are expected into this
  weekend. Humid conditions are likely to kick off the 4th of
  July weekend.

- Isolated and scattered thunderstorm activity is possible
  Wednesday. Thunderstorms are also possible in the afternoon
  and evening of Friday, the Fourth of July.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 401 AM EDT Tue Jul 1 2025

Outside of a few transient -shra that drifted across W Lake Superior
reaching the far W UP in the early hours after midnight EDT, dry
weather has returned. Mostly clear skies are expected the remainder
of the morning as the mid level trough continues to move E away from
the region.

Within the broad mid level trough pattern across E Canada, a
shortwave travels just N of Lake Superior today. The attendant cold
front and PVA with this wave look to remain primarily outside the
CWA, and increasing dry air due to the weak sfc ridging building in
from the SW will also work against associated precip. If these
features are able to dive far enough south to impact our area, iso
-shra would graze the N tier of the UP dropping a few hundreths or
ra...currently not the solution reflected in the fcst. What also
briefly could produce some -shra is a lake breeze off Lake MI near
the Garden Peninsula. SBCAPE will be lower today, mainly below
800j/kg and bulk shear will generally be 30 kts or less outside of
the Keweenaw, so no organized convection is anticipated, but a few
hundreths of ra is possible (15-20% chance). Otherwise light E to NE
winds around 10 mph are expected for most outside the lake breeze
influence with some gusts up to 20-25 mph in the Keweenaw.

Given its N proximity to the passing shortwave, Isle Royale has a
much better shot at seeing shra and possibly even some -tsra this
afternoon/evening (still fairly low, 20-40% chance). Bulk shear will
be at least 40 kts, but any developed storms would be heading toward
a more stable environment and away from supportive forcing. From the
wind field aloft, some gusty sub severe winds are possible on the
island, but small hail looks like an unlikely secondary threat given
low mid level lapse rates struggling to stay above 5C/km and
unimpressive instability.

Mostly clear skies are expected tonight as temps settle into the 50s
to low 60s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 225 PM EDT Mon Jun 30 2025

Long term period begins Wednesday with a mid-level low descending
southeast through northern Ontario and mid-upper level ridging
stretching north just east of the Canadian Rockies. Initial wave
with the descending trough axis will dive through the region
Wednesday afternoon, with the main shortwave following along the
northern and eastern portions of Lake Superior Wednesday evening and
Wednesday night. Growing instability along with the lake breeze may
be enough to support a wave of showers and/or thunderstorms drifting
southeast through the region. Models suggest greater likelihood of
the focus being across the south half, with chances increasing into
Wisconsin. Severe weather is not expected, but there is a window in
the early afternoon where enough shear looks to be in place to
support stronger updrafts capable of small hail and stronger winds
should we destabilize enough. Any isolated or scattered convective
activity that develops should diminish in the evening hours. Surface
high builds in afterwards which will linger Thursday overhead. This
will work to keep the region mostly dry.

Friday, the 4th of July, mid-upper level ridge axis moves through
the Great Lakes with multiple impulses pressing through the
Central/Northern Plains. GEFS 500mb height spaghetti plots depict
enough variances to suggest some level of uncertainty in when these
will lift into the Great Lakes. This continues to be reflected in
the GFS, CA, and EC deterministic suites as well. Its possible an
early wave may bring showers and storms to the region Friday morning
and or showers and thunderstorms later in the day. 12z guidance
continues to suggest timing could result in impacts to 4th of July
outdoor plans in the afternoon and evening hours. In addition,
latest LREF continues to suggest a non-zero chance for strong to
severe thunderstorms should enough vertical forcing exist, which is
unclear at this point. As we get closer, suspect better consensus of
when and where peak instability/shear and forcing for ascent will
align. Afterwards, timing and spatial differences become more
pronounced, with the eventual cold front potentially moving through
Saturday or Sunday. Depending on the timing of the front, Saturday
additional showers and storms will be possible and humid conditions
with warm to hot temperatures may be realized.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 747 AM EDT Tue Jul 1 2025

VFR conditions are expected through the entire duration of the 12Z
TAF period. W to NW winds today between 8-12 kts may gust up to 20-
25 kts at SAW and CMX, but only mentioned in the CMX TAF for now.
Winds settle below 10 kts tonight, turning SW.

&&

.MARINE...
Issued at 401 AM EDT Tue Jul 1 2025

Pressure rises today will increase W to SW winds to 15-25 kts,
strongest over the W half of the lake. This will build waves up to 4
ft over the N Central portion of the lake for this evening. A few
stray thunderstorms are possible near Isle Royale this afternoon
with the main threat being stronger winds mixing down to the lake
surface. Winds settle below 20 kts tonight, allowing for waves to
fall below 4ft again. W to SW winds rise to ~15-20 kts again over
the W half of the lake on Wednesday before becoming light (mainly 15
kts or less) and variable for Thursday. Southerly winds gradually
increase to 20 kts on Friday, remaining elevated into the weekend.

&&

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

&&

$$

SHORT TERM...Jablonski
LONG TERM...JTP
AVIATION...Jablonski
MARINE...Jablonski/PK