083
FXUS63 KMQT 221817
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
217 PM 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.

- High swim risk through this evening for the Lake Superior
  beaches of Marquette and Alger counties.

- Other than a low chance (15-30%) of showers Tuesday into
  Wednesday southeast and east, dry weather is expected this
  upcoming week with a trend toward above normal temps again
  late in the week.

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

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

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 217 PM EDT Sun Sep 22 2024

Water vapor imagery shows a well-pronounced midlevel shortwave
moving through northern Ontario, while at the surface, the
associated cold front is already through most of Upper Michigan.
Rain showers lingering in the far eastern UP should come to an end
by the evening. Skies are largely clearing behind the front with
ridging extending out from the Plains. Still, with cool NW flow
(around 4C at 850mb) over the 15-18C waters of Lake Superior, some
lake clouds are apparent over the northwest and north-central UP.
Soundings really begin to dry out at lower levels into the evening,
however, so we may be able to see some more clearing while flow
turns more anti-cyclonic.

Meanwhile, NW winds remain elevated, with gusts up to 20mph common
across the area. Higher gusts to 20-30mph will remain possible
across the Keweenaw through the afternoon. Where skies are clearing
out, temperatures have been able to climb up into the lower to mid
60s, but to the east, we may struggle to get out of the 50s this
afternoon.

Temperatures quickly fall back into the 40s across most of the UP
under clear skies tonight, and with a pretty sharp inversion present
among some of the model soundings, patchy fog will be possible. As
temperatures dip further into the 30s in the typically cooler
locations throughout the interior-western UP, some patchy frost may
also develop. However, if lake clouds can be more persistent than
expected, temperatures may come in a couple degrees warmer.

&&

.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 /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 116 PM EDT Sun Sep 22 2024

While low cloud cover is scattering out at IWD with mainly VFR the
rest of the day, MVFR ceilings persist at CMX and SAW with satellite
showing some lake clouds developing amid cooler NW flow. Drier air
working in should allow ceilings to lift to VFR into the evening,
then VFR is expected at all terminals the rest of the forecast
period. However, with light winds and clear skies tonight, there is
a slight chance for some patchy fog development tonight. However,
confidence is too low to include in the TAF at this time. Otherwise,
expect NW winds to turn gusty at times today, with gusts up to 20-
25kts possible especially at CMX.

&&

.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...
  Beach Hazards Statement until 10 PM EDT this evening for
     MIZ005-006.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...LC
LONG TERM...Jablonski
AVIATION...LC
MARINE...Jablonski