923
FXUS63 KMQT 160942
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
542 AM EDT Sun Jun 16 2024

.KEY MESSAGES...

- Possible strong to severe thunderstorms this evening/tonight
  and Monday. Primary threat tonight: large hail.

- Very warm early in the work week, with frequent chances for
  showers and thunderstorms throughout.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 536 AM EDT Sun Jun 16 2024

Widespread rain showers have been lighting up the radar mosaic all
night, and lightning has now increased to the southwest on current
imagery as a warm front advances toward Upper Michigan.  This
morning`s convective activity is in association with a shortwave
trough currently situated over central Iowa and is expected to be
non-severe as it spreads across Upper Michigan in the WAA corridor.

After this initial round, shortwave ridging will result in a lull in
activity around mid-day.  But, focus then quickly turns to a
boundary that will be making its way across Minnesota and into far
northwest WI that will be the source of decent low-level convergence
later in the day.  The threat for strong to severe thunderstorms
will be dependent on how well the environment can destabilize after
this first round of showers and thunderstorms.  And, this will
likely not come until later in the day/evening when boundary layer
heating peaks.  With 0-6 km bulk shear approaching 30kts and MUCAPE
values in excess of 2000 J/kg to the southwest per forecast
soundings, the west/southwestern portions of Upper Michigan will
need to be closely monitored from Mon 00Z to 06Z when that
aformentioned boundary makes its way across Upper Michigan. And,
as 700-500 mb lapse rates approach 6-8C/km, the primary threat
will be large hail.

With early round of rain, did back off on temperatures a bit
for today with maximums in the upper 70s/low 80s (west and
central interiors) to low 70s (east). And, as usual, cooler near
the lakeshores with upper 60s/low 70s. Overnight lows will be
be warm and muggy in the upper 50s to mid 60s.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 503 AM EDT Sun Jun 16 2024

Active weather continues through the extended period as troughing
deepens over the western U.S. and ridging amplifies over the Eastern
Seaboard. This pattern will cycle very warm and moist air over us
early in the work week, in addition to many chances for showers and
thunderstorms throughout. With strong shearing and abundant CAPE in
the atmosphere, some severe weather could occur early this week.
More details follow below.

As the Great Lakes region remains situated in between the high-
amplitude ridge and digging western trough Monday through Tuesday,
southerly flow continues to pump in a warm, moist airmass with
dewpoints well into the 60s and even above 70F Monday and Tuesday.
Monday will start off with rain chances as a subtle shortwave tracks
through the area. Convection will be most likely across the western
UP, closer in proximity to the weak wave as well as the frontal
boundary that will be stalled out just to our west. Early on, shear
is rather limited, and though we will be plenty unstable given such
high dewpoints, lower to midlevel capping is apparent in soundings.
An early start to our convection may also limit destabilization.
That said, will not rule out some hail in morning/early afternoon
convection if we can realize the full potential of the ~1000j/kg of
CAPE analyzed over the area. Showers and storms will also have the
impact of limiting temperatures over the western UP to the 70s,
while the eastern half of the UP stands a better chance of reaching
the lower to mid 80s. Will note that guidance is really struggling
to come into agreement on the spatial extent of PoPs for the
daytime, with some models showing a far greater eastward expansion
than others.

Most of the UP should dry out Monday evening as the shortwave exits
northward and the eastern ridge begins to build NW-ward again. That
said, the western UP is not out of the woods as theta-e advection
increases overnight on the nose of an impressive 40-50kt LLJ that
will be directed into the Upper Midwest. Quite impressive CAPE in
excess of 1000j/kg and bulk shear in excess of 40kts indicate a
potential for strong elevated convection overnight, with the main
risks being hail and gusty winds. Will also note a potential for
heavy rain, given PWATS in excess of 1.5in and a potential for
training storms ahead of a very slowly-moving front. Very important
caveat: the front remains well off to our west, and guidance
continues to just graze the western UP and western Lake Superior
with PoPs.


Dry weather is looking likely across most of the UP through Tuesday
while the frontal boundary stalled out over MN finally begins to
slowly creep eastward. Under sunny skies, temperatures climb even
higher than on Monday, possibly peaking in the 90s in many locations
during; it`s not out of the question that we could set a heat record
or two come Tuesday as ensemble guidance shows temperatures around
the 99th percentile of modeled climatology. If there is one upside,
southerly winds will be fairly elevated given the tight pressure
gradient over the area; expect gusts around 20-25mph for much of the
UP.


The aforementioned frontal boundary crawls over the Great Lakes
Tuesday night through Wednesday, and looks to stall out just to our
south into Thursday. Expect additional rain shower and thunderstorm
chances as this moves through, with temperatures cooling close to
normal. As more zonal flow moves over us with weak high pressure
setting up shop over northern Ontario and the Northern Plains,
expect to see the rain and thunderstorm chances continue as
shortwaves continue to ride the upper-level flow across our area. A
more trough-ey pattern sets up next weekend, and though details on
track, timing, and strength of any particular features remain
uncertain, this will in general keep rain chances in through the end
of the forecast period.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 130 AM EDT Sun Jun 16 2024

Conditions will deteriorate overnight into Sunday morning as a
system spreads rain into the region. Expect all sites to fall to
MVFR by morning, possibly IFR at KSAW by late morning/early
afternoon. Wind shear will also be likely at all terminals overnight
into Sun morning and could last through the period at SAW. Gusty
winds will develop by morning at all sites.

&&

.MARINE...
Issued at 503 AM EDT Sun Jun 16 2024

Winds generally out of the southeast this morning continue to gust
up to 20-25kts across the eastern and north-central portions of the
lake, but gusts increase to 25-30kts across the eastern half of the
lake this afternoon while winds turn more southerly. In addition,
some southerly gusts up to 30 knots will be possible along the south
Lake Superior nearshores throughout the day, with a few gale force
gusts up to 35 knots being possible near Grand Marais and Munising
during the afternoon hours. Winds weaken to 20 knots or less by late
Sunday afternoon/evening and remain that way until Tuesday, when
some southerly winds of 20 to 25 knots could be seen across much of
the lake. Light winds of 20 knots or less returns Tuesday night and
could remain through the rest of the week.

Several rounds of showers and storms are expected today through
Tuesday with a frontal boundary stalled out over MN eventually
moving through the area by midweek. Some severe weather is possible
over the lake, particularly over the west, Monday through Monday
night; the primary severe threat is hail, followed by winds. In
addition, while significant wave heights look to be generally 4 feet
or less over the next several days, we could see wave heights get up
to 4 to 6 feet over the eastern half Sunday given the stronger
southeast to southerly winds.

&&

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

&&

$$

SHORT TERM...TDUD
LONG TERM...LC
AVIATION...Voss
MARINE...LC