837
FXUS63 KMQT 060927
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
527 AM EDT Sun Oct 6 2024

.KEY MESSAGES...

- Cold air aloft will force light lake effect rain showers today across
  the northwesterly lake effect bands and over the east half
  occasionally (15-35%) on Monday and Tuesday.

- Dry weather is expected in the back half of the work week, but
  fire weather concerns are limited by light winds.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 525 AM EDT Sun Oct 6 2024

Water vapor imagery and RAP analysis show a vigorous, well-defined
shortwave/closed low moving east across northern Ontario early this
morning. The associated cold front extending south from this low
passed through Upper Mi late evening and early this morning bringing
showers and storms to much of the fcst area, except southern
portions of Menominee and Delta which received little if any
rainfall at all. Locations over north central and eastern Upper Mi
received heavy rainfall at times from the storms with 1.52 inches
measured here at NWS Marquette which fell just 0.02 inches
short of a daily rainfall record. In the wake of the cold front
much of the U.P. has seen clear skies overnight per IR satellite
imagery. Wraparound moisture and cold advection clouds in the
wake of the system are just starting to move into the far
western U.P counties in the past hour.

The colder air (850 mb temps dropping near 0C) and moisture wrapping
back back into the area in the wake of the cold front will generate
scattered to numerous lake effect rain showers today into tonight
over mainly the west-northwest wind lake effect belts. Coverage will
be greatest over the east where the cyclonic flow is maximized.

The other bigger impact today into tonight will be the windy
conditions in the wake of cold front. CAA and a strong pressure
gradient south of the low over Ontario will lead efficient mixing up
to ~5kft where 35-40kt winds present during the day will result in
widespread west becoming northwest gusts between 25-35mph. Higher
gusts are expected in the Keweenaw Peninsula ~40-50mph. Given that
the latest ECMWF probabilities of gusts exceeding 34kts is +90% in
the entire Keweenaw Peninsula, the Wind Advisory will continue as is
for Sunday (6AM - 8PM EDT Sun). Model soundings do show some
potential for more isolated gusts up into the 40mph range across
much of the UP during the day, especially near Lake Superior.
Otherwise high temps will peak late morning/early afternoon in the
50s, warmer in the east and south-central. Also, given the strong
gales across Lake Superior, waves building up to 7-12ft may cause
some minor lakeshore erosion along the western shores between
Ontonagon and Keweenaw Counties as well as in the east along Alger
and Luce County beaches.

As ridging builds in from the west, expect clearing with showers
generally ending in the west by evening. Isolated to scattered
showers will linger across the east half into the early overnight
where the 850 mb thermal trough will be located with temps blo 0C
and the flow still weakly cyclonic. Showers then should finally
taper off over the east late. With clearing skies from the west min
temps will plummet tonight. Expect readings to drop near freezing
over western interior where northwest winds become light and areas
of frost are possible. Elsewhere, min temps from the mid 30s to
lower 40s will be more common.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 442 AM EDT Sun Oct 6 2024

The weather over the next week will be determined by troughing over
the central CONUS and a trough that will be over the Ontario/Quebec
line Monday morning. The trough will stall over Quebec while ridging
continues to build over the Plains through the first half of the
work week, resulting in cold Canadian air being forced south over
the UP, which in combination with shortwaves pivoting around the
Quebec trough will support some lake effect cloudiness and
occasional scattered light rain showers through Tuesday night. Dry
weather is expected from then into the weekend as ridging and the
associated surface high move over the Great Lakes. The main impacts
of the long term forecast will be the gusty westerly winds
especially over the Keweenaw on Sunday and the frost/freeze
potential Sunday night into Monday.

Monday morning will have a quiet start with slight 500mb height
rises causing only partly cloudy skies in the morning. A shortwave
pivoting around the main trough over Quebec will work in tandem with
lake effect (850mb temperatures falling near 0 C over a ~15 C lake)
to cause some light rain showers in the east half. CAMs show varying
degrees of coverage in showers and some models like the HRRR and NAM
Nest show some convective components, but even the 90th percentile
of the HREF only shows around 0.05 inches of accumulation in Luce
County by the end of the day Monday. While winds wont be as gusty as
previous days, wind gusts are still forecast to be around 25-30 mph
out of the northwest in the afternoon, though RHs only falling to
around 40% will keep fire weather concerns in check. Light rain
chances (~30%) linger into Tuesday, but impacts should be low to
none. For the first couple days of the week, under cool
northwesterly flow aloft, expect highs around 60, slightly below
normal with lows around freezing in the interior and around 40 at
the shores.

With high pressure of near 1022 mb over the Great Lakes, the back
half of the week will be dry. Lighter winds will be expected under
higher pressure and current minimum RH forecasts are only for the
mid 40 percent range, so fire weather concerns should lessen
somewhat despite the lack of precipitation. High temperatures will
gradually rise through the week, with NBM highs in the 70s by
Friday. The next chances for precip come over the weekend where
ensemble spread is high, but PoPs rise to at least 30% as ridging
breaks down to some degree with a clipper shortwave. Not much of a
pattern change is suggested in longer term models, with the CPC
outlooks through the end of October suggesting the best
probabilities for above average temperatures and below average
precipitation.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 136 AM EDT Sun Oct 6 2024

There will be a period of clear skies early this morning behind
last night`s cold fropa. Increasingly colder air and low-level
moisture arriving on Sun will then lead to MVFR cigs developing
at all terminals. Some lake enhanced -shra will also develop,
especially at CMX. W to wnw winds on Sun will gust to 30-35kt at
IWD/SAW and to 40-45kt at CMX. Expect improvement to VFR
Sunday evening as ridging and drying scour out low clouds from
the west.

&&

.MARINE...
Issued at 442 AM EDT Sun Oct 6 2024

Westerly gales to 40 knots will overspread Lake Superior this
morning and forcing waves over the lake up to 15 feet, highest south
of Caribou Island this evening as winds become more northwesterly.
Winds will fall below gales around midnight tonight in the west half
and around 4 AM Eastern in the east half. A secondary shortwave
passing over the eastern portion of the lake will keep westerly
winds around 25 knots in the forecast through Monday before falling
below 20 knots Tuesday. High pressure will keep winds light over the
lake until the weekend, when the next system potentially arrives
near the Great Lakes, but uncertainty is still high that far out in
the forecast.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Wind Advisory until 8 PM EDT this evening for MIZ001-003.

Lake Superior...
  Gale Warning until 8 PM EDT /7 PM CDT/ this evening for LSZ162-
     240-241.

  Gale Warning until 2 AM EDT Monday for LSZ242-263.

  Gale Warning until 4 AM EDT Monday for LSZ243>251-264>267.

Lake Michigan...
None.

&&

$$

SHORT TERM...Voss
LONG TERM...GS
AVIATION...Voss
MARINE...GS