821
FXUS63 KMQT 130947
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
547 AM EDT Sat Jul 13 2024

.KEY MESSAGES...

- Seasonably warm Saturday through Monday with periods of
  showers and thunderstorms, some of which could be strong to
  severe.

- Cooling and drying trend into the midweek portion of next week
  with the arrival of high pressure.

&&

.SHORT TERM /TODAY/...
Issued at 446 AM EDT Sat Jul 13 2024

Water vapor imagery/surface analysis early this morning indicate
subsidence over Upper Michigan due to upper level ridging.  This
equates to mostly clear skies and a warm morning with temperatures
holding in the 60s across the forecast area per current ground-based
obs. Limited cloud cover and WAA in the southerly surface flow will
push today`s highs well into the 80s with downsloping areas near
Lake Superior approaching the 90 degree mark. In addition to
the heat, focus will be on a shortwave trough approaching from
the west this afternoon. CAMs/HRRR solutions, though, keep any
convective development confined to the far western portions of
the UP mid/late afternoon with the shortwave being counteracted
by high pressure over the remainder of the forecast area until
the evening hours.

&&

.LONG TERM /TONIGHT THROUGH FRIDAY/...
Issued at 531 AM EDT Sat Jul 13 2024

The extended forecast starts off active with two systems late this
weekend and early next week as shortwaves ride the zonal flow aloft.
Meanwhile, low level southwesterly flow will support WAA and
moisture advection, priming the atmosphere for strong to possibly
severe storms. High pressure then returns mid next week, resulting
in a drier and quieter weather period.

Starting tonight, a shortwave positioned over the MN
Arrowhead/Western end of Lake Superior progresses east across the
region. The thunderstorms possible tonight will depend on ongoing
upstream convection and potential redevelopment later in the day, so
confidence in timing and location is still low. A handful of the
CAMs indicate convection currently over SW Manitoba will continue
moving east with the shortwave, developing into an MCS somewhere
over the northern half of MN late this evening. The 6Z HRRR leans
into the redevelopment solution and stays mainly to the south of our
CWA. While the NAM/FV3 are the solutions are the more of a worst
case situation, taking the system southeast right across the entire
CWA, the NSSL hardly yields any thunderstorms anywhere in our area.
The likely solution is for any MCS to track southeast, mainly
through WI. Given the uncertainty, the best chances right now for
thunderstorms are in the west, mainly near the WI/MI state line
between 3Z and 9Z Sunday. Main threats will be winds given the
inverted-v soundings and convective mode. That said, bulk shear
around 25-30 kts, mid level lapse rates around 7C/km, and MUCAPE
~1000-2000 J/kg would support hail as well. Otherwise, expect mild
lows in then mid 60s.

Any lingering convection Sunday morning moves out leaving a mainly
dry start to the day. Given the elevated dew points nearing 70 in
the east and warm temps in the 80s (possibly some low 90s south
central), instability returns; the 7/13 0Z HREF mean MUCAPE builds
up to 1000-2000 J/kg. The shear profile will be supportive of any
thunderstorms that do develop with around 30 kts of bulk shear.
Forcing looks to be primarily driven by any lake breeze convergence,
which leaves low confidence in thunderstorms again. The UP then
returns dry Sunday night with lows in the upper 50s to mid 60s,
cooler in the interior.

Monday into Monday night brings another round of showers and
thunderstorms as another shortwave tracks across the region and an
associated sfc low follows east over Lake Superior/northern Ontario.
Bulk shear sees a significant increase from previous convection with
up to 1000 J/kg of MUCAPE, so some strong to severe storms are
possible ahead of the cold front.

Although a mid level closed low will be shifting east through
northern Ontario and Quebec Tuesday and Wednesday, sending a
shortwave over the area during that period, dry weather returns as
high pressure begins building in from the northwest. How long this
dry period will last will depend on when the next shortwave
progresses southeast through the Upper Great Lakes as the mid level
ridge over the western CONUS slowly shifts east. Slight chances hold
off until late next weekend. Otherwise, a cooler period is expected
accompanying the high pressure and northwest flow.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 128 AM EDT Sat Jul 13 2024

VFR conditions and light winds will prevail in this TAF period. Some
fog/mist will be possible overnight at KIWD and KSAW, but confidence
is low. Guidance continues to lack concensus with tomorrow`s
convective event. At this point, it continues to look as if KIWD may
begin seeing thunderstorms by Saturday afternoon.

&&

.MARINE...
Issued at 547 AM EDT Sat Jul 13 2024

Southerly winds remain below 20 kts today as the pressure gradient
stays light. South winds increase tonight over the east to around 20
kts with a 15-30% chance for gusts reaching 25 kts tonight ahead of
the next disturbance. Some strong to severe storms are possible
tonight, especially across western Lake Superior. The main threats
are damaging winds, but large hail is also possible. Another round
of storms is expected Monday into Monday night as a low pressure
system moves through the area. Patchy dense fog is also a
possibility in the wake of any precipitation. Following the
Monday/Monday night low presusure`s cold front, west winds increase
to around 20 kts across much of the lake Monday night and Tuesday.
As high pressure begins to build in mid next week, winds look to
fall back below 20 kts, remaining light through the remainder of the
forecast period.

&&

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

&&

$$

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