500
FXUS63 KMQT 300706
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
306 AM EDT Sun Jun 30 2024

.KEY MESSAGES...

- Rip currents and dangerous swimming conditions at Lake
  Superior beaches of Alger and Marquette counties through this
  evening.

- Dry weather Sunday morning through Monday evening under high
  pressure.

- Next rounds of showers and thunderstorms arrive Monday night,
  continuing into Wednesday.

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

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 418 PM EDT Sat Jun 29 2024

Thunderstorms continue across the far eastern UP this afternoon,
with a cold front not far behind in the central UP. These storms
have a history of producing large hail, and with MUCAPE still up to
2000 j/kg and sufficient shear to sustain updrafts, will not rule out
additional strong convection from eastern Luce county southwest
through Green Bay. Meanwhile, outflow from earlier storms in
northern Marquette and Alger counties is quite apparent on radar,
and has touched off additional weak showers. That said, most
convection apart from clusters currently working through Luce,
southern Schoolcraft, and Mackinac counties have struggled to climb
high enough even to produce lightning - not surprising, given modest
capping indicated in model soundings and the afternoon NUCAPs
profiles.

Upstream, additional spotty shower activity has become apparent.
Given cooler post-frontal flow as winds turn over to the NNW, moist
lower levels, and another shortwave dropping from northern MN
through the UP tonight, expect spotty shower activity to continue at
least through the first half of the night. This would be most likely
across portions of the UP where NNW flow is upsloping (so, much of
the higher terrain of the western UP, portions of the north-central
UP, and across Alger and northern Luce counties). Skies gradually
clear out the rest of the night, with temperatures largely bottoming
out in the lower to mid 40s. However, some cooler spots in the
western and north-central UP may fall even further into the upper
30s.

Strong post frontal northwesterly winds are expected to create
dangerous swimming conditions for Marquette and Alger counties
through this evening. A Beach Hazards statement is in effect.

&&

.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,
particiarly 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 /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 108 AM EDT Sun Jun 30 2024

High pres over the Northern Plains will settle over the western
Great Lakes later today and tonight. Very dry air mass associated
with the high will result in clearing skies overnight with clear
skies then persisting into Mon morning. VFR will prevail at IWD/CMX
thru this fcst period. MVFR cigs at SAW will scatter out to VFR
before sunrise with VFR persisting for the rest of the fcst period.

&&

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

&&

$$

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