644
FXUS63 KMQT 302307
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
707 PM EDT Mon Jun 30 2025

.KEY MESSAGES...

- Scattered showers and storms are expected this afternoon and evening.
  Stronger storms may bring gusty winds and hail.

- 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 225 PM EDT Mon Jun 30 2025

Overhead our forecast area, weak mid-level wave pressing through,
alongside about 1000j/kg SBCAPE and 30-40 kts of effective bulk
shear, per SPC mesoanalysis, is supporting showers progressing west
to east through western Upper Michigan into the central third. These
will continue growing in the next few hours. Additionally, with
continued destabilization expected alongside continued lake breeze
activity in the central/east, isolated to scattered thunderstorms
should develop. Given that shear is in place and there`s the
potential for lake breeze enhancement, large hail or stronger winds
will be possible. West of the boundary, clear skies or clearing
skies are noted across the western third of Upper Michigan. SPC
mesoanalysis paints this clear sky region with ~1500j/kg of SBCAPE
with about 30kts of effective bulk shear.

GOES Water Vapor imagery and RAP analysis highlight a trough
extending south into Minnesota with an attendant weak cold front
supporting showers and some thunderstorm activity across northern
Minnesota and the Arrowhead. This front may be the focus for
additional thunderstorm activity later this afternoon over the
western half of Upper Michigan given the ongoing destabilization.
Similarly, to the central and east in the next few hours, strong
storms capable of producing hail and stronger winds will be possible.

Trough axis and cold front will dive through Upper Michigan this
evening, followed by northwest flow aloft thanks to upstream ridging
building into the Canadian Rockies. Surface ridging will inch into
the region alongside a drier airmass. This will help keep the region
partly cloudy to clear tonight into Tuesday. The first shortwave
driving southeast within the broad trough to our north looks to
glance the northern and eastern portions of Lake Superior tonight,
but should remain mostly dry for a majority of our forecast area.
Overnight lows tonight in the upper 50s to low 60s look to warm into
the upper 70s to low 80s Tuesday, then cool back into the upper 50s
to low 60s Tuesday night.

&&

.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 /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 706 PM EDT Mon Jun 30 2025

VFR conditions are generally expected for the TAF period, although
some showers and storms (mainly over SAW) could lower conditions to
MVFR or lower for an hour or two early this evening. Overwise,
expect flow to become westerly this evening and west to
northwesterly Tuesday.

&&

.MARINE...
Issued at 225 PM EDT Mon Jun 30 2025

SW winds increase to 15-20 kts this afternoon ahead of a cold front
this evening. As this moves W to E across the lake, winds veer W and
become ~10-15 kts across the lake. Pressure rises behind a departing
low pressure on Tuesday will increase W to SW 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 Tuesday evening. Winds
settle below 20 kts Tuesday night, allowing for waves to settle
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 into the late portion of the work week.

&&

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

&&

$$

SHORT TERM...JTP
LONG TERM...JTP
AVIATION...TAP
MARINE...PK