948
FXUS63 KMQT 052223
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
623 PM EDT Sat Oct 5 2024

.KEY MESSAGES...

- Critical fire wx conditions end west to east through early
  evening. Relative humidity increases, but gusty south winds to
  30-40mph continue into early evening.

- Band of showers and some thunderstorms, lasting only 30-60
  minutes, rapidly moves across the area tonight. Five percent
  chance of strong winds and small hail with strongest storms.

- A Wind Advisory is in effect for the Keweenaw Peninsula on
  Sunday with strong westerlies behind the front gusting above
  45 mph.

- Cold air aloft will force light lake effect rain showers on
  Sunday 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 314 PM EDT Sat Oct 5 2024

Water vapor imagery and RAP analysis show a vigorous, well-defined
shortwave over southern Manitoba. At the sfc, associated 987mb low
pres is nearing Lake Winnipeg. Cold front extends sse from the low,
bisecting MN. Ahead of the front, tightening pres gradient and
mostly sunny skies to build mixed layer have resulted in gusty s
winds up to 30-40mph this aftn. The drier models had a pretty good
handle on the mixing to lower dwpts today, particularly across nw
Upper MI thru central Upper MI and then eastward across northern
portions of eastern Upper MI. With RHs in the upper 20s to mid 30s
percent range, the gusty winds and ongoing drought conditions are
leading to critical wildfire conditions this aftn.

Dwpts are already rising thru the 40s and into the 50s F in WI in
the flow ahead of the approaching cold front. These higher dwpts are
beginning to spread across the MI-WI stateline over western Upper
MI, and during the next several hrs, dwpts will continue to increase
from the sw, resulting in RH increasing from sw to ne across the
area. RH may hang down toward 30pct e of Munising thru about 6 PM.
Winds will probably tick up a bit more in the next few hrs. Have
some concerns that downslope locations around Copper Harbor and in n
central Upper MI near Lake Superior, especially Marquette to
Munising, may have 2-3hrs of wind advy level gusts above 45mph. Will
continue to monitor.

Tonight, attention turns to cold front which will surge e across the
area. While shra have not developed along the front yet, looks like
a narrow band of sct to bkn shra/tsra will accompany the front as
increasing forcing works on the ongoing prefrontal increase in
moisture. For most, pcpn will last no more than 30-60 minutes.
Narrow band and quick movement will limit pcpn amounts, maybe 0.3 to
0.4 inches at most where heaviest shra occur. With the strong wind
fields, strong sfc wind gusts may occur, particularly with cells
that produce heavier rainfall. Some hail not out of the question.
Skies will quickly clear with fropa and passage of the shra. Late
tonight, increasingly colder air flowing into the area on westerly
winds (850mb temps down to around 0C across western Lake Superior by
12z) along with increasing low-level moisture wrapping around sfc
low pres in northern Ontario will result in stratocu
spreading/developing into western Upper MI. A few shra may develop
off of the lake into nw Upper MI prior to 12z.

&&

.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 429 PM EDT Sat Oct 5 2024

Windy conditions are expected on Sunday in the wake of tonight`s
cold front. A second cold front positioned over central Upper MI
Sunday morning will drape southwest into WI, continuing east through
the day as the mid level trough tracks east through northern Ontario
sending the sfc low toward Hudson Bay. A stronger pressure gradient
and efficient mixing up to ~5kft where 35-40kt winds are 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).
Note: While the strongest and most persistent winds are expected in
the Keweenaw, model soundings do leave potential for more isolated
gusts up into the 40mph range across much of the UP during the day,
especially near Lake Superior. Otherwise highs peak late
morning/early afternoon in the 50s, warmer in the east and south-
central. Meanwhile, CAA from northwest flow brings 850mb temps drop
to near 0C. Although Lake Superior has begun to drop closer to
normal, it still remains fairly warm around 15C which will be
supportive delta-Ts for lake effect showers. Coverage will be best
over the east where the cyclonic flow is maximized. 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.

Drier air begins to work its way in from the northwest Sunday night
as high pressure builds in over the Mississippi Valley. This begins
to diminish showers from west to east. Light accumulations from
Sunday into Sunday night should remain below 0.25". Skies clear out
from west to east as a result of the drier air, allowing for temps to
drop into the 30s to low 40s, warmer by the lakeshores and in the
east where cloud cover lingers on longer. Expect areas of frost
Sunday night, particularly in the interior west and south-central.
While winds begin to taper down Sunday night, gusts into the 20mph
range may persist into Monday in the Keweenaw and in the east.
Although Sunday night/Monday morning would be the last frost-freeze
headlines, near freezing temps are likely away from the lakeshores
in the early portions of this week.

Light lake effect rain chances will periodically grace the eastern
UP Monday and Tuesday as the troughing aloft stalls over Quebec and
minor shortwaves pivot around and through the east. However,
soundings leave much to desire for available moisture with only
shallow saturation near the top of the inversion. Also, as strong
winds continue to mix up the lake over the next few days, sfc temps
will drop lowering delta-Ts. Thus, certainty in coverage and
intensity of any shortwave-boosted lake effect diminishes with time.
Scattered cloud cover over the east with little to no accumulation
is the most likely solution.

Mid level ridging builds east from the Plains to the Great Lakes
late next week into the weekend, keeping sfc high pressure over the
Great Lakes for much of that time. This means another stretch of
mostly dry weather is expected with temps well above normal. Despite
this period of drier conditions, winds remain light under this high
pressure somewhat limiting fire weather concerns. Will need to
monitor this for any changes as a good portion of the eastern UP is
in a Severe Drought.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 623 PM EDT Sat Oct 5 2024

A cold front will move quickly across the area tonight, accompanied
by a narrow band of shra and a few tsra in the 01-05z time frame.
Pcpn will only last 45 minutes to perhaps up to 90 minutes at each
terminal. Brief MVFR will be possible, mainly at SAW and CMX. Skies
will quickly clear with fropa. Increasingly colder air and low-level
moisture arriving early 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.

&&

.MARINE...
Issued at 458 PM EDT Sat Oct 5 2024

South-southeast gales this afternoon over the eastern two thirds of
Lake Superior continue into this evening ahead of a cold front,
strongest winds are expected north of the Keweenaw with high end
gale force gusts to 45 kts possible. As a low pressure system tracks
through northern Ontario, a cold front progresses across the lake
tonight. Gales to 40 kts will remain most likely along the US/Canada
maritime border ahead of the eastward sweeping cold front. Winds
quickly veer southwest behind the front, then west late tonight as
they begin to quickly increase again. High end gales to 40-45 kts
are expected Sunday morning over the west half with gales up to 40
kts over the east. Winds fall below gales from west to east Sunday
night and linger around 25 kts through Monday evening. High pressure
over the Great Lakes will keep wind gusts mainly below 20 kt for the
remainder of the week. Some elevated thunderstorms will be along the
cold front tonight, with some being capable of producing strong
winds and small hail. Wave heights with the southerlies ahead of the
cold front will peak east of Isle Royale at up to 15 feet, with the
westerlies behind the front forcing a broad swath of 10-15 ft waves
from the Western Lake Superior Buoy to Whitefish Point. Waves fall
below 4 feet across the lake by Tuesday morning.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Wind Advisory until 7 PM EDT this evening for MIZ001-005-006.

  Wind Advisory from 6 AM to 8 PM EDT Sunday for MIZ001-003.

  Red Flag Warning until 8 PM EDT this evening for MIZ006-007-
     014-085>088-095>097.

Lake Superior...
  Gale Warning from 2 AM EDT /1 AM CDT/ to 8 PM EDT /7 PM CDT/
     Sunday for LSZ162-240-241.

  Gale Warning until midnight EDT Sunday night for LSZ242-263.

  Gale Warning until 2 AM EDT Monday for LSZ243>251-264>267.

Lake Michigan...
  Gale Warning until 2 AM EDT Sunday for LMZ221-248-250.

&&

$$

SHORT TERM...Rolfson
LONG TERM...Jablonski
AVIATION...07
MARINE...Jablonski