009
FXUS63 KMQT 240812
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
412 AM EDT Mon Jun 24 2024

.KEY MESSAGES...

- Showers and thunderstorms possible this afternoon and evening.
  Severe weather is not expected.

- A slight risk (~15%) of damaging wind and hail in the far west
  associated with thunderstorms Monday night into Tuesday
  morning.

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

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

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 104 PM EDT Sun Jun 23 2024

Clear skies with pockets of mostly cloudy skies have been present
over Upper Michigan today. This has yielded a mix of temperatures,
but overall most areas have climbed into the mid-60s, with a few low
70s here and there. DLH radar returns this morning showed scattered
showers across the northern fringes of the Arrowhead and some light
rain or sprinkles over western Lake Superior. These are associated
with a closed mid-level low and preceding shortwave moving through
western Ontario/northern Minnesota. Some of these have started
showing up in Upper Michigan, but its uncertain if anything is
reaching the ground at this point.

As we progress through the remainder of the afternoon/evening, the
wave aloft opens up as it moves through Upper Michigan. Some very
modest instability may support additional showers and some
thunderstorms this afternoon. Any convective development should
progress southeast and weaken into the late afternoon and evening
hours. High pressure builds in tonight, supporting a mostly clear
night with lows dipping into the high 40s to mid 50s, warmest lake-
side. The combination of cooler conditions, recent rainfall, and a
low level inversion may support fog development across portions of
western Upper Michigan tonight.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 411 AM EDT Mon Jun 24 2024

Tuesday morning, a cold front draped from a 989mb low over far
northern Ontario and its parent 500mb trough will push through the
UP. While some thunderstorms will likely remain over some portions
of the UP, the extent that thundershowers remain is uncertain. Among
the 00Z HREF run, only the HRRR shows widespread thunderstorms
present by 12Z Tuesday with the other members showing only isolated
to scattered showers remaining. Attempted to somewhat split the gap
in these solutions with this forecast, but confidence is somewhat
low given the spread in the ensemble solutions. Any lingering storms
are unlikely to be severe as the better instability will be to the
south while better forcing will be to the north with probably less
than 1,000 J/kg of MUCAPE to work with over the UP. MOS guidance
suggests high temperatures in the central UP climbing to the mid 80s
with the 75th percentile of the NBM still hinting that 90s could be
possible in some typical warm spots in the south. Mixing behind the
front will allow for dew points to not be as high as originally
forecast. The other thing that mixing will do is create some gusty
conditions especially in the west and over the Keweenaw. This
forecast will reflect gusts in the 30-35 mph range, but the ceiling
for gusts over the Keweenaw could be higher as the HREF suggests
locally over 50% chances for 40 mph gusts Tuesday evening.

A dry period then is expected into Thursday night as a ~1015 mb high
pressure descends southeast through the Great Lakes from the
Canadian Prairie Provinces. While a shortwave trough will pass over
the UP Wednesday morning and both the Euro ensemble and GEFS show a
20-30% chance of precipitation, this forecast will reflect dry
weather with the subsidence associated with the dry weather. Cool
northerly surface flow on Wednesday will cause highs to only reach
the 60s, and potentially only the high 50s along the eastern Lake
Superior shores. Attention then turns upstream as a trough over the
Pacific NW makes landfall Wednesday night, then continues east along
the U.S./Canada border and reaches the Upper Great Lakes by
Saturday. This will support cyclogenesis in the northern Rockies
Thursday night/Friday with the low ejecting east-northeast to just
north of Lake Superior for Friday night/Saturday. While spread is
still high on the details of this system, the general trend is for
this low pressure to weaken as it approaches the Upper Great Lakes,
so hazardous weather seems unlikely at this forecast issuance. Drier
weather looks to return the rest of the weekend as a stronger high
pressure near 1025 mb settles over the UP by Sunday evening. As the
high shifts east to start next week, PoPs increase as another low is
expected somewhere in the Plains, but spread is high on the
track of said low.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 204 AM EDT Mon Jun 24 2024

Lingering relatively moist dew points will result in some patchy
fog overnight which could impact the terminals. The best chance
of visibility restriction will be at IWD where conditions could
bounce between MVFR and IFR. Otherwise, VFR conditions are
expected during the day on Monday under high pressure. The
approach of a cold front from the west will bring in a threat of
showers/t-storms into the western U.P. this evening. While there
is considerable model uncertainty at this time on the evolution
of these showers and possible storms tonight, I did include
showers with a vicinity TS for IWD by late evening/overnight
into Tue. A tightening pressure gradient ahead of the front will
also result in LLWS at all the terminals Monday evening.

&&

.MARINE...
Issued at 411 AM EDT Mon Jun 24 2024

Expect winds below 20 kts through the day as high pressure ridging
passes over Lake Superior. South winds increase to around 20 kts
tonight ahead of a passing cold front. Tuesday, gusty westerly to
northwesterly winds will increase to around 25 knots over the
western and central portions of the lake and to near 30 knots
between Isle Royale and the Keweenaw, with a 10% chance of a few
gale force gusts. Winds taper off Wednesday morning as they veer
north, remaining below 20 kts under high pressure through Thursday.
A weakening low pressure approaching the region will allow for gusts
near 20 kt, but given the uncertainty in the track of the low, the
timing and direction of these gusts is difficult to determine with
this forecast package. High pressure returns Sunday and ushers in
light winds.

Strong to severe storms are possible in the west tonight into
Tuesday with the passing cold front. Waves will be strongest north
of the Keweenaw Peninsula Tuesday afternoon and evening (4-6 feet).

&&

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

&&

$$

SHORT TERM...JTP
LONG TERM...GS
AVIATION...07
MARINE...GS