473
FXUS63 KMQT 231127
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
727 AM EDT Mon Sep 23 2024

.KEY MESSAGES...

- Moderate swim risk through this morning for the Lake Superior
  beaches of Alger County.

- Other than a low chance (15-40%) of showers Tuesday into
  Wednesday in the southeast and eastern U.P., dry weather is
  expected this upcoming week with a trend toward much above
  normal temps again late in the week.

- Patchy frost is possible (~20%) for typical cold spots of
  interior western Upper Michigan both this morning and Tuesday
  morning.

- Supportive setup for typical fall radiative patchy fog (~25%)
  each morning this week.

&&

.SHORT TERM /TODAY/...
Issued at 441 AM EDT Mon Sep 23 2024

Water vapor imagery/surface analysis early this morning show Upper
Michigan under the influence of shortwave ridging as yesterday`s
trough pushes out of the region.  This has meant quiet weather all
night across the forecast area, but the drawback has been the cold
temperatures with ground-based obs reporting widespread mid 30s
across the interior west and the usual cold prone areas of Baraga
Plains and Yellow Dog are reporting 30 and 29 degrees, respectively.
As a result, it would not be unlikely to see some patchy frost
this morning across those areas. For the remainder of today,
expect plenty of sunshine and dry weather. But, the ENEerly
onshore flow will prevent high temperatures from topping off
above the 60s.

&&

.LONG TERM /TONIGHT THROUGH SUNDAY/...
Issued at 434 AM EDT Mon Sep 23 2024

Tonight remains quiet as a sfc high pressure over Quebec extends
weak ridging into the Upper Great Lakes. Meanwhile, a mid-level
shortwave over IA lifts northeast to the Great Lakes and a trough
over the Dakotas digs southeast. The antecedent dry airmass will
help keep the UP dry, but cloud cover will increase overnight from
the south ahead of the shortwave which could be a limiting factor in
radiational cooling. Given the strong inversion, areas where skies
remain clear longer should dip into the mid 30s to low 40s,
particularly cooler in the interior west. This leaves potential for
some patchy fog and frost development in the interior west. Lows by
the lakeshores will be in the mid to upper 40s.

The trough continues to dig southeast toward the Lower Mississippi
Valley through Tuesday night while the shortwave tracks northeast
over the Great Lakes. This takes a weak ~1008mb low pressure over IL
on Tuesday northeast to Lower MI by Tuesday evening, then over Lake
Huron Tuesday night. While some light showers may scrape along the
UP shores of Lake Michigan during the day Tuesday and lift over the
east Tuesday night, the better forcing and moisture will remain to
our south and east. Thus most will remain dry and accumulations will
remain low below 0.1". Highs peak just above normal in the mid 60s
to low 70s. Lows Tuesday night settle into the upper 30s to low 50s,
colder in the interior west where skies remain clear.

By Wednesday, strong mid level ridging will be positioned over the
Rockies. The troughing over the Great Lakes will progress eastward
through the end of the work week as the mid level east pushes east
to the Great Lakes. Also, the southeast diving trough forms a closed
low over the Lower Mississippi Valley. This supports dry weather the
rest of the work week with one low confidence exception. The
Canadian and NAM have the trough over northern Ontario extending
further southeast into the Great Lakes Wednesday and Wednesday night
as it propagates east. Also, both models note better available
moisture so that PVA forces some scattered showers on Wednesday.
Given the strong ridging building in from the west, opted to keep
the forecast dry for now, but will monitor future model trends.
Southerly flow brings temps back above normal temps with highs in
the 70s and lows in the 40s to mid 50s. MOS guidance has toggled
back and forth between some spots maybe hitting 80 late in the week.

While the dry and warm pattern likely will persist much of the
weekend, uncertainty begins to grow as a tropical system develops in
the Gulf of Mexico. The exact details on how this low interacts with
the closed low already in the south are murky, but low chances
(<25%) for showers return Sunday onward as tropical moisture surges
north from the Gulf.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 726 AM EDT Mon Sep 23 2024

VFR conditions for the duration of the TAF period with shortwave
ridging over the region.

&&

.MARINE...
Issued at 434 AM EDT Mon Sep 23 2024

With high pressure moving northeast over the Upper Great Lakes
today, variable winds remain mainly below 15 kts. East winds
increase this evening with some gusts up to 20 kts, gradually
veering south tonight as the high pressure moves to Quebec;
strongest winds are expected over the west half of the lake.
Southerly winds taper down below 15 kts Tuesday morning. Although a
low pressure system tracks through Lower MI and the Central Great
Lakes late Tuesday into Wednesday, winds are expected to remain
below 20 kts through the remainder of the forecast as stability
increases mid week and high pressure returns late this week.

&&

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

&&

$$

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