826
FXUS63 KMQT 242047
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
447 PM EDT Mon Jun 24 2024

.KEY MESSAGES...

- Line of thunderstorms moves through the forecast area tonight,
  some storms could be strong to severe and produce damaging
  winds and large hail.

- Tuesday will be the warmest day of the week with highs in the
  mid 70s to mid 80s. Gusty winds to 30 mph are also expected,
  especially over the Keweenaw.

- Next round of precipitation is expected Thursday night into
  the weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 143 PM EDT Mon Jun 24 2024

Current mesoanalysis across the region places an upstream shortwave
moving through northern Minnesota and a cold front tied to a surface
low moving through Lake Winnipeg not far behind. Precip associated
with this is trending down per DLH radar and GOES IR. To the south,
mid-level ridging extends across the Plains with subtle shortwaves
perturbations embedded atop. At the surface, a surface low was
observed moving across eastern South Dakota along with a
southeastward draped warm front and several surface troughs tied to
the mid-level perturbations. Across our forecast area, surface high
has allowed for clear skies to largely dominate; at the time of this
publishing though, high clouds streaming eastward into the region
associated with the shortwave pressing through Minnesota was
observed on GOES Vis imagery. With these mostly clear skies and
predominately southerly flow, daytime temps have warmed into the 70s
while dewpoints in the 50s have been observed.

As we progress through the remainder of the afternoon and overnight
tonight, upstream weakening showers in Minnesota will continue to
weaken as it presses into Lake Superior/western Upper Michigan. HRRR
and other CAMS suggest it may hold together enough to support some
showers in our forecast area late this afternoon/early evening.
Otherwise, expect temps to continue climbing into the upper 70s to
low 80s and increasing cloud cover.

Impressive instability will continue building on the south side of
the decaying shower activity over Minnesota. As this area of
instability grows and southwesterly low level winds strengthen this
evening, a line of thunderstorms will develop over central
Minnesota. These will grow upscale and evolve into a bowing MCS as
they stream southeast along the instability gradient. CAMS appear to
be coming into better agreement that the strongest storms will stay
south of our forecast area, but storms capable of mostly damaging
winds can`t be ruled out early in the event. Some large hail will
also be possible. The main risk area will be in the counties
bordering Wisconsin. North of this bowing segment, the HRRR and to
some degree, the FV3 and NAMNEST resolve a secondary line of showers
and thunderstorms across the Arrowhead into Ontario, then press
these into Lake Superior and Upper Michigan. Some large hail and
maybe strong winds will be possible with these storms if the
materialize, but confidence in these developing is low to medium (25-
50%) given their proximity to the main bowing segment and the lack
of a consensus among the various CAMS solutions. If this develop,
these and the northern fringes of the MCS pressing southeast, will
press eastward through Upper Michigan, likely clearing the east just
after sunrise. While confidence in the evolution is lacking
somewhat, consistent temporal signatures in the various CAMS suggest
the main period of thunderstorms to be between 5z and 11z with the
most likely period for strong to severe being early in the event.

&&

.LONG TERM /TUESDAY THROUGH MONDAY/...
Issued at 446 PM EDT Mon Jun 24 2024

Starting Tuesday morning, the mid level trough will be situated
over far northwestern Ontario with the associated sfc low just ahead
of it at 988mb near the western shores of James Bay. This low`s cold
front will be draped southeast along the west end of Lake Superior
and into northwest WI. Lingering convection from tonight will likely
be over the far east where the warm front continues shifting east
out of the area. With instability dropping off, confidence in severe
weather is low for the morning as this moves out. Dry weather
returns to all in our CWA by mid morning as the cold front presses
east. Stronger mixing begins behind the cold front resulting in some
gustier west to northwest winds up to 30 mph and drier RHs down into
the 30%, possibly some upper 20s near Iron Mountain. Strongest gusts
are expected in the Keweenaw and northwest, coupled with the lower
RHs. Tuesday is also expected to be the hottest day this week with
highs in the 70s to mid 80s, warmer in the south central UP. That
said, there are no wildfire concerns given the recent wet pattern.
As the cold front makes it`s way through the area, the ARW and HRRR
try to initiate some isolated thunderstorms along the east near Lake
Michigan. The 6/24 12Z HREF mean SBCAPE does build up to 1000 J/kg
in that region, but with model soundings looking moisture deprived.
Left afternoon precip out of the forecast for now.

Tuesday night into Wednesday, the mid level trough continues east
into Quebec and is quickly followed by a shortwave rotating over the
Upper Great Lakes. An additional cold front dropping south will
shift winds out of the north by Wednesday morning and keep winds up
around 5-15 mph through the night, especially over the east and in
the Keweenaw. Lows are expected in the mid 40s to low 50s. Also
given the shortwave, added in some slight chance PoPs late Tuesday
night into Wednesday. Note: There is low confidence at the moment in
location/timing, but nothing impactful is expected. Dry weather and
clearing skies then is forecast for Wednesday afternoon as highs
peak in the 60s. However, those near the eastern Lake Superior
shores may stay in the 50s throughout the day.

With weak high pressure ridging continuing over the region into
Thursday night, dry weather prevails. Radiative cooling Wednesday
night brings lows into the 40s, coolest in the east where the drier
airmass is located. With Highs on Thursday only are expected to warm
up into the low 70s.

Meanwhile, a trough just east of the Pacific northwest will move
onshore Wednesday night. This trough progresses east along the
international border toward the Upper Great Lakes by Saturday
morning with 1 to 2 shortwaves shooting out ahead of it. This will
support cyclogenesis in the northern Rockies Thursday night with the
low ejecting east-northeast to the northern end of Lake Superior for
Friday night/Saturday. Thus, PoPs increase Thursday night into the
weekend. With the low weakening as it moves through and little
instability, hazardous weather seems unlikely at this point. Drier
weather looks to return the rest of the weekend into Monday as high
pressure returns, but confidence is growing in another low pressure
system pushing off the Rockies and moving northeast into the
Upper Great Lakes region for early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 143 PM EDT Mon Jun 24 2024

VFR conditions will prevail this afternoon and evening, followed by
a rapid deterioration as a line of thunderstorms moves into Upper
Michigan. Expecting most activity between 5 and 11z, with the
greatest potential for severe winds, maybe some large hail, at KIWD
early on in the event. Expect ceilings to fall to MVFR/IFR after the
line moves through with some brief fog/mist developing before the
sunrise. Tuesday, gusty winds are expected to develop as ceilings
improve. Initial thoughts are KCMX could gust near 30kts from the
west, but some models indicate higher being possible.

&&

.MARINE...
Issued at 446 PM EDT Mon Jun 24 2024

Southeast winds increase this evening to around 20-30 kts, backing
south tonight ahead of the cold front; strongest winds are expected
over the east between the north and eastern Lake Superior buoy`s
where there is a 15% chance for gale force gusts to 35 knots
tonight. Strong to severe storms are possible tonight into Tuesday
morning ahead of the cold front. On Tuesday, gusty westerly winds
are expected behind the cold front to 20-30 kts. Strongest winds are
expected over the central third of the lake between Isle Royale and
the Keweenaw. This will be another period with even higher potential
for some gale force gusts to 35 kts. (Chance of gusts exceeding 34
kts ~40%). This period of longer fetch and stronger winds will help
waves build up to 4-6 feet Tuesday afternoon and evening north of
the Keweenaw. Winds around 20-25 kts veer north Tuesday night behind
an additional cold front that drops south across the lake before
tapering off below 20 kts Wednesday morning. With high pressure over
the lake through Thursday, winds are expected to mainly remain below
20 kts. A weakening low pressure tracking through the Upper Great
Lakes early this weekend will allow for gusts near 20 kt Friday and
Saturday. High pressure returns Sunday and ushers in light winds.

&&

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

&&

$$

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