176
FXUS63 KMQT 301832
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
232 PM EDT Sun Jun 30 2024

.KEY MESSAGES...

- Rip currents and dangerous swimming conditions are possible at the
Lake Superior beaches of Alger and Marquette counties the rest of
the afternoon.

- Dry weather continues through Monday evening.

- There is a slight chance (<20%) for patchy frost across portions
of the interior-western UP tonight.

- Next rounds of showers and thunderstorms arrive Monday night,
continuing into Wednesday. Gusty southerly winds are also expected
Tuesday.

- Warm and wet pattern expected to continue well into July.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 231 PM EDT Sun Jun 30 2024

Robust upper ridging over the Plains is supporting a sprawling
1028mb surface high centered over MN this afternoon. With strong
subsidence over the UP, there is hardly a cloud in the sky. In spite
of this, temperatures remain quite cool; temperatures are only
climbing into the lower 60s across much of the UP, while shoreline
locations and the easternmost portions of our CWA are struggling
even to break out of the upper 50s under chilly NW flow off of Lake
Superior. NW winds are staying somewhat gusty across the eastern
half of the UP, but gusts should fall back heading into the
evening.

Tonight, as the aforementioned high pressure becomes centered
overhead, even stronger radiational cooling and calm winds will lead
to widespread overnight lows in the upper 30s to lower 40s. The
frost potential across the interior-western UP is still difficult to
pin down, with most of the guidance staying just warm enough to
preclude frost. Only about 10% of href ensemble members reach the
mid 30s, while the NBM 10th percentile also only flirts with the mid
30s. Will note, however, that some spots in the western half of the
UP fell farther into the 30s than expected, with the "winner" of the
night (Watton) reaching as low as 34F. Therefore, have been just
confident enough to come in a couple degrees under guidance,
particularly across Iron and southern Baraga counties, where we
may just get cool enough for patchy frost. This will continue
to be monitored/adjusted as needed.

In addition, dangerous swimming conditions for Marquette and Alger
counties are expected through this afternoon.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 305 AM EDT Sun Jun 30 2024

Long term period, beginning Monday, kicks off with a 1027mb surface
high overhead while mid-upper level ridging extends from the Gulf of
Mexico northward through the region. This will support a dry day,
but the next system moving closer will support increasing cloudiness
in the west by afternoon. Daytime highs should climb into the 70s.

Upstream on Monday, broad troughing will exit the northern Rockies,
moving into the northern Plains and lifting a shortwave through the
region by Monday night into early Tuesday. Increasing isentropic
ascent will support rain lifting into the west overnight. Some
thunderstorms can`t be ruled out given the elevated instability
characterized by 200-500 j/kg MUCAPE. As Tuesday progresses, ridge
of theta-e advection moves through the region enabling the initial
swath of rain to shift east. This while a stout 35-45kt 925mb LLJ
moves through as well. Similarly to Monday night, thunderstorms
can`t be ruled out given the elevated instability, but severe
weather is not expected. The LLJ will likely support a breezy day,
particularly on the downslope spots near Lake Superior. EFI and
SOT highlight the abnormality of this wind as it relates to the
climate record and the EC ensemble system suggests a 50+%
chance of 34kt gusts in the high terrain and downslope spots in
Alger, Marquette, and Baraga counties. Additionally, the same
suggests the higher wind potential in Gogebic County.

Expect a break in the rain by afternoon from west to east. The last
slug of moisture and the system`s cold front presses through
overnight Tuesday and Wednesday, finally clearing eastern Upper
Michigan sometime Wednesday afternoon. Over the course of the entire
event, deterministic EC suggests 0.5-1.5 inches of rain may fall
while the GFS appears to be more tampered. With this being said,
both their ensemble systems suggest the south-central and east would
be most favored (20-50% chance) for these higher rain amounts. High
pressure and a dry start 4th of July follow, but afternoon showers
and thunderstorms may develop by afternoon in the west ahead of hte
next system moving in. This system looks to press into the Upper
Great Lakes Thursday night through Friday. There`s enough
differences in the timing of this system to make me uncertain on
when the rain will end Friday and its possible it may persist into
the evening hours.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 126 PM EDT Sun Jun 30 2024

VFR conditions to prevail for duration of TAF period with high
pressure over the region. Winds generally out of the north will be
breezy at times especially at SAW this afternoon, then winds turn
light and variable tonight before shifting over to the south for
Monday.

&&

.MARINE...
Issued at 305 AM EDT Sun Jun 30 2024

Pressure rises and cold air advection should gradually weaken early
this morning, enabling winds to begin settling across Lake Superior.
Expecting winds below 20kts to return lake-wide by mid-late morning.
High pressure begins sliding in from the west through the day,
maintaining these light winds through at least Monday.

Another system presses in from the west Monday night, bringing with
it waves of rain and maybe some thunderstorms, into Wednesday. These
rain showers may support fog developing and periods of low
visibility on the lake. A stout 925mb low level jet of 35-45 kts
will also come with this system. This will support increasing
southerly winds Monday night into Tuesday. Internal probabilistic
tools suggest a low probability (<25%) that these stronger winds
will mix down to the surface, and there`s some validity to this
given the increasingly warm airmass and stability over the lake at
the time. With this being said though, localized terrain driven
influences should support small pockets of mixing down low end
gales, particularly downwind of the lakeshores east of Marquette and
along the northern shores of the Keweenaw. Latest EC ensemble system
suggests a 10-30 percent chance of low end gales north and east of
the Keweenaw over the open waters. Given the setup and the consensus
of the strength of the low level jet, I suspect these percentages
will increase as we approach the event. Another slug of moisture
will lift through Tuesday night into Wednesday while winds settle
down. The cold front presses through west to east through the day
Wednesday, allowing winds to become westerly/southwesterly through
the day Wednesday. Another period of stronger winds, upwards of 25-
30kts, looks possible between the Keweenaw and Isle Royale Wednesday
in this southwesterly flow. High pressure and light winds return
Wednesday night into Thursday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement until 6 PM EDT this evening for MIZ005-
     006.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...LC
LONG TERM...JTP
AVIATION...LC
MARINE...JTP