957
FXUS63 KMQT 291832
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
232 PM EDT Sun Jun 29 2025

.KEY MESSAGES...

- Thunderstorms are expected this evening and tonight. There is
  a slight chance that storms could be strong to severe storms
  this evening over central Upper Michigan. Should organized
  storms occur, large hail and damaging winds will be possible.

- 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 MONDAY NIGHT/...
Issued at 1242 PM EDT Sun Jun 29 2025

GOES Water Vapor and RAP analysis position a broad mid-level trough
over the Northern Plains and central Canada with a few different
shortwaves across the Upper Midwest atop a slowly progressing cold
front and warm front. This warm front lifted into the forecast area
behind this morning`s showers and thunderstorms, allowing for
heating into the 70s and 80s for much of the region. With dewpoints
in the mid to upper 60s and plenty of clear skies noted, we`ve been
able to destabilize to 500-1000j/kg of SBCAPE, per SPC mesoanalysis.
Increasing low level jet is expected this afternoon, which will help
initiate convection this evening ahead of the approaching cold front.
CAMS continue to lack considerable consensus, but generally suggest
a line or clusters of storms moving into the forecast area with a
growing consensus on it being mostly during the evening hours. 30-
35kts of effective bulk shear and a 25-35kt 925-850mb LLJ should be
sufficient for an environment capable of storm organization and
stronger updrafts. Should this occur, strong to severe storms will
be possible. The HREF matches the aforementioned general consensus
and given the anticipated timing of the background environment, peak
convective potential looks to fall 22-4z over Upper Michigan, with
strong storms potentially lingering over Lake Superior to near 8z.
Main severe weather risks appears to be strong to damaging winds,
but large hail can`t be ruled out. Otherwise, downpours and frequent
lightning should be expected in any thunderstorm. Thunderstorms will
track east or northeast and likely exit the east near sunrise.

Monday, a secondary cold front/slug of cold air advection will move
southeastward into the forecast area in the afternoon/evening,
coincident with the mid-level trough axis. There continue to be
questions about how much we`ll destabilize during the day, but if
we`re able to destabilize enough, scattered showers and
thunderstorms should develop by afternoon/evening. Severe weather
isn`t expected, but if enough thunderstorm organization can occur, a
stronger storm capable of stronger winds and small hail will be
possible. Any convective activity that occurs should diminish
overnight. Expect daytime temps to climb into the mid-upper 70s to
low 80s and lows Monday night to fall mostly in the low 60s to mid
50s.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 231 PM EDT Sun Jun 29 2025

Long term period begins Tuesday with downstream trough axis
stretching south through the Lower Great Lakes with upstream ridging
building up western CONUS and Canada. To the north, upper level low
is expected to be over northern Manitoba with a preceding shortwave
in western Ontario. At the surface, high pressure stretches across
the Plains. As the day progresses, the surface high will settle
southeast some, then flatten out over the middle Mississippi River
Valley Wednesday. The aforementioned waves to the north are expected
to press southeastward, with the first moving along the northern and
eastern lakeshores of Lake Superior by Tuesday afternoon. Despite
its slightly southern placement compared to yesterday`s guidance
package, precip probabilities appear minimal and mostly confined to
Ontario given little forcing and dinurally driven instability. The
second wave also has trended more south, but overall, there continue
to be geographic and temporal differences among the deterministic
suites, which is reflected into their ensemble counterparts. These
same packages are in agreement on this upper level low intensifying
as it takes on a negative tilt over central Ontario, resulting a
deepening surface low. A cold front associated with these features
looks to drop southeast through Upper Michigan Wednesday night into
early Thursday. Diurnally driven instability may result in isolated
showers or thunderstorms by afternoon Wednesday, perhaps aided by
lake breezes, but the better forcing appears focused north and south
of our forecast area. Should any showers or storms develop, severe
weather is not expected. Surface high builds in afterwards which
will linger Thursday overhead. This will work to keep the region
mostly dry.

Friday, the 4th of July, weak ridging to near zonal flow sets up
across the northern tier with multiple weak impulses embedded within
the flow. Closer to the surface, a warm front looks to stretch
across the Northern Plains or Upper Midwest. 12z guidance continues
to suggest timing could result in impacts to afternoon and evening
plans in Upper Michigan. In addition, latest LREF suggests a non-
zero chance for strong to severe thunderstorms. This is likely given
the temporal and geographical differences of these features among
the ensemble members. As we get closer, suspect better consensus of
when and where peak instability and forcing for ascent will align.

Daytime temperatures Tuesday and into the weekend look largely to
span the upper 70s to low 80s, with potential for heating into the
mid 80s Friday. Overnight lows are expected to fall mostly into the
50s to low 60s, except widespread 60s Friday night.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 116 PM EDT Sun Jun 29 2025

Primarily VFR conditions are expected during this TAF period.
However, shower and thunderstorm activity is expected to develop
this evening, which could impact all terminals. Timing has trended a
little later then previous forecast but latest guidance continues to
suggest activity exit east of the terminals tonight. There is still
uncertainty in coverage though, so Prob30 groups were included.

&&

.MARINE...
Issued at 231 PM EDT Sun Jun 29 2025

Winds largely remain under 15 kts lake wide, however, isolated to
scattered thunderstorms developing in the UP this evening could
cause some gusty and erratic winds over the central and eastern lake
as they push northeast during the overnight hours into Monday
morning. By Monday afternoon/evening, a weak cold front is expected
to move west to east across the lake, increasing westerly gusts in
the western half between 15-20 kts before falling back below 15 kts
Monday night. Pressure rises behind a departing low pressure on
Tuesday will once again increase W to SW gusts in the western lake
upwards of 25 knots, accompanied by waves near 4 ft. This will
mainly occur between the Keweenaw and Isle Royale and persist into
the midweek.

&&

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

&&

$$

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