080
FXUS63 KMQT 220838
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
438 AM EDT Sun Sep 22 2024

.KEY MESSAGES...

- Showers end from west to east through today as the cold front
  exits the UP. Gusty NW winds behind the front, with the
  highest gusts along the eastern shores of Lake Superior up to
  30 mph.

- Other than a low chance (15-25%) of showers Tuesday afternoon
  through Tuesday night associated with a low pressure passing
  through Lower Michigan, dry weather is expected this week.

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

- Supportive setup for patchy fog (~25%) each morning next week.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 321 PM EDT Sat Sep 21 2024

Latest water vapor imagery shows a well-defined shortwave trough
lifting northeast into northern Ontario and northern MN this
afternoon. This shortwave trough will move into the Upper Great
Lakes later tonight and Sunday, sending a sfc cold front across
Upper Mi tonight into Sunday morning. WAA and a 40+ kt LLJ max ahead
of the cold front have already supported showers and scattered t-
storms early this afternoon into north central WI and portions of
western Lake Superior. A few showers may have made it into far
western Upper Mi but showers have generally dissipated moving into
into ridging and the associated dry and stable air mass across Upper
Mi. While it`s been more cloudy into western Upper Mi due the
convection drifting into that area, ridging has supported more
sunshine into central and eastern areas of the U.P. this afternoon.
Afternoon temperatures have generally been in the 70s to lower 80s,
warmest inland east and coolest west under the clouds.

Heading into this evening and tonight, the vort max/shortwave will
continue to lift northeast through northern Ontario which will send
the mid-level trough axis across Upper Mi later tonight into Sunday.
As the system`s associated cold front moves across Upper Mi tonight
into Sunday morning, showers along the cold front will most likely
move into far western Upper Mi early this evening and then spread
into central Upper Mi late evening and eastern Upper Mi overnight.
Instability along the front is not particularly impressive,
generally 500 j/kg MUCAPE, with the best of that south along the WI
border. Effective shear along the front when showers will be
occurring also generally looks like it will be 30 knots or less, so
not really expecting any severe storms, but maybe a stronger storm
with some dime-sized hail could develop south central along the WI
border where marginal instability and shear appear to be maximized.
Look for min temps lowering into the 50s behind the cold front
tonight. Northwest winds behind the front could gust near 30 mph
late tonight/early Sunday along the tip of the Keweenaw.

&&

.LONG TERM /TONIGHT THROUGH SATURDAY/...
Issued at 437 AM EDT Sun Sep 22 2024

Tonight through Monday, the mid level trough over Lake Superior and
northern Ontario lifts northeast toward Hudson Bay while another
trough to the west moves southeast to the Dakotas. This allows for
weak high pressure to shift northeast from MN to northern
Ontario/Quebec. The associated cold front and showers are expected
to already have exited the CWA by tonight, leaving clearing skies
tonight save for a scattered low level deck over north-central Upper
MI. This low level cloud deck looks to clear out Monday morning
leaving mostly Sunny skies the rest of the day. A drier airmass
behind the cold front and subsidence from the weak high pressure
will help yield a cooler night. Lows tonight are expected in the mid
30s to upper 40s, warmer by the Great Lakes, especially beneath
scattered low cloud deck in north-central UP. Some patchy frost may
develop in the interior west and also some patchy fog may develop in
the far west late tonight. Highs on Monday will peak in the 60s.

Monday night through the mid portion of next week, the trough over
the Dakotas dives southeast toward the Lower Mississippi Valley
while a shortwave over the Mid Mississippi Valley moves northeast
over Lower MI and the Lower Great Lakes. Meanwhile ridging is
building over the western CONUS. This sends a low pressure system
over southern IL on Tuesday to lower MI. Then the low takes a slower
and more northerly track Tuesday night through Wednesday night to
Quebec. While some light showers may scrape the south and eastern
portions of the UP Tuesday afternoon and Tuesday night, not much of
any accumulations are expected as the better forcing remains outside
the CWA. Otherwise, highs on Tuesday and Wednesday will be just
above normal in the mid 60s to mid 70s. Monday night could be
another cool night with lows in the upper 30s to upper 40s. Patchy
frost is possible again in the interior west. Model soundings show a
more impressive inversion Monday night compared to tonight, so more
patchy fog is possible Monday night across the entire UP.

The mid level ridge positioned over the Rockies Wednesday morning
shifts east toward the Great Lakes for next weekend. There are some
discrepancies how the trough that dives southeast to the Lower
Mississippi Valley mid next week interacts with potential tropical
system. That said, the stronger ridging moving over the Great Lakes
region favors drier weather with warmer than normal temps in the 70s.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 130 AM EDT Sun Sep 22 2024

Cold front moving through Upper Michigan tonight and Sunday will
support cloud bases lowering and ceilings developing, mainly at
KSAW, although KIWD and KCMX may experience MVFR ceilings this
morning before scattering out. Expect conditions to improve through
the day Sunday. Models continue to suggest that showers, perhaps
mixed with some thunderstorms, will develop later tonight and impact
KSAW. These same models have, notably, struggled all night with
upstream convection moving into the U.P., so confidence is low.
Post frontal airmass will also support some gusts of 20-25kts,
mainly at KSAW and KCMX.

&&

.MARINE...
Issued at 437 AM EDT Sun Sep 22 2024

A cold front currently over central Lake Superior will continue east
across the rest of the lake this morning. South-southwest winds
ahead of the cold front quickly veer northwest as the front passes,
gusting up to 20-30 kts. Some thunderstorms are possible over the
east half of the lake this morning with the passing cold front,
although no strong to severe weather is anticipated. Waves behind
the front will peak between 4 and 5 feet along the western UP shores
this morning and over the east half of the lake between 6 and 7 feet
later this morning through this evening; waves fall below 4 feet
lakewide by Monday morning. Northwest winds gradually fall below 20
kts from west to east across the lake this afternoon through this
evening, veering north tonight. Although a low pressure system
tracks through Lower MI Tuesday night and Wednesday, winds are
expected to remain below 20 kts the remainder of the forecast.

&&

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

&&

$$

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