141
FXUS63 KMQT 232034
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
434 PM EDT Sun Jun 23 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.

- 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 /MONDAY THROUGH SUNDAY/...
Issued at 433 PM EDT Sun Jun 23 2024

Starting Monday, Upper MI will be underneath mid level ridging with
a trough over New England and another more broad trough over the
Canadian Prairie Provinces. With the northern end of a 1015 mb high
pressure ridge shifting southeast through the Great Lakes, we stay
quiet and dry. Meanwhile, the western trough progresses east toward
Saskatchewan/Manitoba throughout the day and its associated sfc low
deepens to around 990mb just north of Lake Winnipeg. This set up
increases southerly flow, increasing warm air and moisture
advection; PWATs increase to around 1.7" by Tuesday evening. Some
lake breezes are possible in the afternoon, but may struggle against
the southerly flow. Otherwise no noteworthy weather is expected.
Highs are expected in the 70s to low 80s.

Monday night through Tuesday the mid level trough over Manitoba
moves east, becoming centered just east of James Bay. The associated
sfc low moves east with it, moving through far northern Ontario,
reaching James Bay Tuesday afternoon, and then continuing east into
Quebec Tuesday evening. This sfc low well to the north drapes a cold
front south into the midwest that moves into the far western UP
around 6Z Tuesday, supporting showers and storms aided by isentropic
ascent. The significant uncertainty yet with how the convection
along the front plays out is well represented by the wide range of
solutions among the CAMs. Model soundings show a decent cap and the
6/23 12Z HREF mean CIN is ~100 J/kg Monday evening across much of
the western UP. Also, stronger large-scale ascent with the tough
will remain north of the international border. That said, a small
region of MUCAPE (HREF mean of 1000-2000 J/kg) builds up over
Gogebic/Ontonagon/S Houghton/Iron counties Monday night; values as
high as 2500-3000 J/kg are not out of the question. Mid level lapse
rates will increase to ~7 C/km with bulk shear between 35-40 kts. If
we are able to break the cap with the frontal boundary passing
through as well as a strengthening LLJ, the environment will be
supportive of strong to severe storms with damaging hail and winds
being the main threats.

This event will depend on how upstream convection earlier in the day
plays out. Some solutions including the 12z runs of the NAM
Nest/ARW/FV3 depict a more pronounced MCS developing over northern
MN, progressing through the region. The MCS tracks are spread as
well with some only clipping the WI/MI border while the FV3 tracks
right across our CWA. The HRRR and RAP are not as organized or
strong. Given the potential environment, the SPC slight risk (15%)
for the far west seems appropriate. This event will continue warrant
monitoring as uncertainty remains high. Showers and storms continue
east across the UP through the rest of the day Tuesday as the front
continues out. As the trough presses south in the later part of the
day, PVA supports additional shower and storm chances, mainly over
the east half of the UP. Otherwise, Tuesday is expected to be the
warmest day of the week with highs in the mid 70s to mid 80s. Mixing
behind the front late morning/early afternoon will help alleviate any
early muggy conditions in the morning.

A dry period then is expected Wednesday into Thursday night as high
pressure descends southeast through the Great Lakes from the
Canadian Prairie Provinces. Confidence is growing in the weekend
forecast for a trough over the Pacific NW to make landfall Wednesday
night, then continue east along the U.S./Canada border, and reaching
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. Drier weather looks to return the rest of the
weekend as high pressure returns.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 104 PM EDT Sun Jun 23 2024

A weak shortwave moving through the Upper Great Lakes this afternoon
and evening may support showers at KCMX and KSAW this afternoon, but
otherwise, VFR ceilings are expected to prevail. With clear skies
expected at KIWD/KSAW tonight, fog/mist should develop, bringing the
terminals down to at MVFR/IFR until fog mixes out after sunrise.

&&

.MARINE...
Issued at 433 PM EDT Sun Jun 23 2024

West to northwest winds will diminish through this evening, then
remain below 20 kts through Monday as high pressure ridging passes
over Lake Superior. South winds increase to around 20 kts Monday
night ahead of a passing cold front. Southwest winds behind the
front are expected around 20-25 kts, though a few gusts may be in
the 25-30 kt range between Isle Royale and the Keweenaw Peninsula
Tuesday afternoon. Winds taper off Tuesday night into Wednesday as
they veer north, remaining below 20 kts through the late part of the
week.

Strong to severe storms are possible in the west Monday night into
Tuesday with the passing cold front. Waves will be strongest between
Isle Royale and 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...Jablonski
AVIATION...JTP
MARINE...Jablonski