757
FXUS63 KMQT 231935
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
335 PM EDT Thu May 23 2024

.KEY MESSAGES...

- Slight chance for light showers along the WI/MI state line through
this evening.

- Another shortwave and low pressure system will bring another
  round of showers and a slight chance (around 20% chance) for
  some thunder to Upper Mi late Friday into early Saturday.

- There will be more opportunities for rain next week although
  model uncertainty leads to low forecast confidence on
  timing/extent.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 318 AM EDT Thu May 23 2024

RAP analysis shows a stacked closed low north of Lake Superior
with central surface pressure near 994 mb. While a tight
pressure gradient and tapping into a LLJ caused windy conditions
earlier, the weakening low departing the region is allowing
winds to come down somewhat, though some gusts to 25 mph may
linger throughout the morning.

Despite weakening surface flow, diurnal heating will support cu
development with a few CAMs suggesting some shower development in
the south and interior west. Instability has trended lower with the
last 24 hours of model runs, so confidence in showers of any
strength is low, but left some 15-24% PoPs from 18Z to 02Z. Expect
highs mainly in the mid 60s, close to the climatological normal for
this time of year. The exceptions will be locations downwind of
Lake Superior that will have highs near 60 and the south, which
bias- corrected guidance suggests mid- to upper-70s may be
observed between Menominee and Iron Mountain.

Overnight, winds turn easterly and northeasterly in response to a
00Z GEFS-mean 997 mb low approaching Minnesota. Previous forecasts
had rain arriving in Ironwood by 12Z Friday, but virtually all of
the most recent model runs at varying resolutions have backed
off on the initial line of precipitation, so PoPs have been
largely removed from the overnight time period. Low temperatures
will be in the 40s, near normal for this time of year.

&&

.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 335 PM EDT Thu May 23 2024

Wet, active weather continues on and off through the extended period
before we briefly dry out for the middle of next week.

By Friday, the focus will shift to the next shortwave emerging from
the western CONUS mid-upper level trough. This shortwave lifts NE
through the Plains and Upper Great Lakes, eventually swinging into
Manitoba and Ontario phasing once more with the broader troughing
over the western CONUS/Canadian Prairies. Increasing isentropic
ascent, 850 mb theta advection and moderate q-vector convergence out
ahead of the shortwave will lead to another quick round of showers
across the area beginning late Friday afternoon in the western UP
and spreading eastward during the evening. Instability off soundings
looks pretty minimal, with just a few hundred j/kg of CAPE indicated
in HREF plots, so thunder should be fairly limited. Otherwise,
guidance continues to favor widespread rain amounts of 0.10-0.25in,
but EPS ensembles also show probabilities of 40-60% for amounts of
0.50in or more south central and southeast. Showers quickly exit
eastward during the pre-dawn hours of Saturday with clearing skies
expected as drier air works in.

Saturday should be dry with ridging/subsidence behind the exiting
shortwave. Expect partly cloudy skies and seasonable temperatures
for the rest of the day with highs mostly in the 60s with a few
cooler mid 50s readings near Lake Superior.

There remains quite a bit of uncertainty in the Sunday-Tuesday time
frame regarding the track/strength of the next western CONUS wave
and developing cyclone. This ejects NE from the lee of the southern
Rockies into the Great Lakes region late weekend into early next
week, but many of deterministic models (particularly the GFS, UKMET
and Canadian) as well as ensembles continue to flip-flop on the
exact track with some runs taking a deep system as far north as the
Straits, and others suppressed more over the southern or central
Lower Peninsula and coming in comparatively weaker. A more southerly
route would have little if any wind and rain impacts to the UP,
while the more NW route would bring a chance for more significant
rainfall as well as gusty winds. The ECMWF, on the other hand, has
been the most consistent of the models advertising generally a more
phased and deeper system for the last several runs with a more
northern/western track through the Central Great Lakes, and thus,
greater rain and wind impacts for Upper Mi in the late Sunday into
Memorial Day time frame. Given the huge spread depicted in the
tracks of the ensemble members it`s still too soon to latch onto any
one model solution with great certainty, thus leading to poor
forecast confidence during this time frame. For now, will continue
to lean on the model blend for forecast details and wait a bit
longer for models to sort out their continuity/consistency issues
and hopefully come into better agreement over the coming days.

PoPs persist into Tuesday as the system moves into Quebec, and
associated wraparound moisture curls into the area while another
shortwave ripples through. Most of the models and ensembles do seem
to be in general agreement showing a trend toward ridging and drier
conditions for Wednesday into Thursday next week. Otherwise, expect
more or less seasonable temperatures through the forecast period.

 &&

.MARINE...

Low pressure that impacted the area over hte past couple of days
continues to weaken over James Bay while a weak high pressure ridge
builds over the Great Lakes. Winds have been on the decrease today
in response, still gusting to 20-25 knots out of the west in the
eastern portions of the lake, but dropping below 20 knots to the
west. Winds finally fall below 20 knots to the east later this
evening. The period of light winds doesn`t last long over the
western lake, however, as northeast winds will begin to ramp up to
30 knots late tonight into Friday in advance of another low pressure
lifting from the Northern Plains towards Lake Winnipeg. Guidance
indicates around a 60-70% chance for gales Friday afternoon through
the early evening over the western quarter of Lake Superior. East to
southeast winds gradually increase over the east half of the lake on
Friday but generally stay 20 knots or less, but 25kt gusts will then
become possible for a brief period into the evening and overnight
hours. Winds over the west half becoming southwest behind the low
and the passage of its cold front late Friday night into Saturday
and generally stay in the 15 to 25 knot range. Winds decrease late
Saturday behind the exiting system, then expect light winds of 20
knots or less across Lake Superior for the rest of this weekend as a
high pressure ridge builds over the area. Looking ahead to early
next week, another system moving out of the Plains will head towards
the Great Lakes. This could present another opportunity for gusty
winds, but confidence is low given quite a bit of uncertainty on the
exact storm track.

 &&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  High Wind Watch from 6 AM EDT Wednesday through Wednesday
     evening for MIZ001-003.

  Wind Advisory from 9 AM EDT /8 AM CDT/ to 10 PM EDT /9 PM CDT/
     Wednesday for MIZ002-009.

Lake Superior...
  Gale Warning until 8 PM EDT /7 PM CDT/ Wednesday for LSZ162.

  Gale Warning from 7 AM EDT /6 AM CDT/ to 8 PM EDT /7 PM CDT/
     Wednesday for LSZ240-241.

  Gale Warning from 10 PM this evening to 11 PM EDT Wednesday
     for LSZ242>244-263-264.

  Gale Warning from 2 AM to 11 AM EDT Wednesday for LSZ245>251-
     265>267.

Lake Michigan...
None.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 142 PM EDT Thu May 23 2024

VFR flight conditions are expected to prevail throughout the
duration of the 18Z TAF period. While some lingering gusts in the
20-30 kt range are expected at CMX yet this afternoon, west winds
are expected to taper off into tonight as they become northerly.
This afternoon should see some scattered diurnal cumulus, but no
precip is expected at any of the TAF sites. LLWS is possible at IWD
Friday morning, however confidence was too low to include in this
TAF issuance. Precip and lower cigs with the next low pressure
system look to hold off until after this TAF period ends.

&&

.MARINE...
Issued at 335 PM EDT Thu May 23 2024

Wet, active weather continues on and off through the extended period
before we briefly dry out for the middle of next week.

By Friday, the focus will shift to the next shortwave emerging from
the western CONUS mid-upper level trough. This shortwave lifts NE
through the Plains and Upper Great Lakes, eventually swinging into
Manitoba and Ontario phasing once more with the broader troughing
over the western CONUS/Canadian Prairies. Increasing isentropic
ascent, 850 mb theta advection and moderate q-vector convergence out
ahead of the shortwave will lead to another quick round of showers
across the area beginning late Friday afternoon in the western UP
and spreading eastward during the evening. Instability off soundings
looks pretty minimal, with just a few hundred j/kg of CAPE indicated
in HREF plots, so thunder should be fairly limited. Otherwise,
guidance continues to favor widespread rain amounts of 0.10-0.25in,
but EPS ensembles also show probabilities of 40-60% for amounts of
0.50in or more south central and southeast. Showers quickly exit
eastward during the pre-dawn hours of Saturday with clearing skies
expected as drier air works in.

Saturday should be dry with ridging/subsidence behind the exiting
shortwave. Expect partly cloudy skies and seasonable temperatures
for the rest of the day with highs mostly in the 60s with a few
cooler mid 50s readings near Lake Superior.

There remains quite a bit of uncertainty in the Sunday-Tuesday time
frame regarding the track/strength of the next western CONUS wave
and developing cyclone. This ejects NE from the lee of the southern
Rockies into the Great Lakes region late weekend into early next
week, but many of deterministic models (particularly the GFS, UKMET
and Canadian) as well as ensembles continue to flip-flop on the
exact track with some runs taking a deep system as far north as the
Straits, and others suppressed more over the southern or central
Lower Peninsula and coming in comparatively weaker. A more southerly
route would have little if any wind and rain impacts to the UP,
while the more NW route would bring a chance for more significant
rainfall as well as gusty winds. The ECMWF, on the other hand, has
been the most consistent of the models advertising generally a more
phased and deeper system for the last several runs with a more
northern/western track through the Central Great Lakes, and thus,
greater rain and wind impacts for Upper Mi in the late Sunday into
Memorial Day time frame. Given the huge spread depicted in the
tracks of the ensemble members it`s still too soon to latch onto any
one model solution with great certainty, thus leading to poor
forecast confidence during this time frame. For now, will continue
to lean on the model blend for forecast details and wait a bit
longer for models to sort out their continuity/consistency issues
and hopefully come into better agreement over the coming days.

PoPs persist into Tuesday as the system moves into Quebec, and
associated wraparound moisture curls into the area while another
shortwave ripples through. Most of the models and ensembles do seem
to be in general agreement showing a trend toward ridging and drier
conditions for Wednesday into Thursday next week. Otherwise, expect
more or less seasonable temperatures through the forecast period.

 &&

.MARINE...

Low pressure that impacted the area over hte past couple of days
continues to weaken over James Bay while a weak high pressure ridge
builds over the Great Lakes. Winds have been on the decrease today
in response, still gusting to 20-25 knots out of the west in the
eastern portions of the lake, but dropping below 20 knots to the
west. Winds finally fall below 20 knots to the east later this
evening. The period of light winds doesn`t last long over the
western lake, however, as northeast winds will begin to ramp up to
30 knots late tonight into Friday in advance of another low pressure
lifting from the Northern Plains towards Lake Winnipeg. Guidance
indicates around a 60-70% chance for gales Friday afternoon through
the early evening over the western quarter of Lake Superior. East to
southeast winds gradually increase over the east half of the lake on
Friday but generally stay 20 knots or less, but 25kt gusts will then
become possible for a brief period into the evening and overnight
hours. Winds over the west half becoming southwest behind the low
and the passage of its cold front late Friday night into Saturday
and generally stay in the 15 to 25 knot range. Winds decrease late
Saturday behind the exiting system, then expect light winds of 20
knots or less across Lake Superior for the rest of this weekend as a
high pressure ridge builds over the area. Looking ahead to early
next week, another system moving out of the Plains will head towards
the Great Lakes. This could present another opportunity for gusty
winds, but confidence is low given quite a bit of uncertainty on the
exact storm track.

 &&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  High Wind Watch from 6 AM EDT Wednesday through Wednesday
     evening for MIZ001-003.

  Wind Advisory from 9 AM EDT /8 AM CDT/ to 10 PM EDT /9 PM CDT/
     Wednesday for MIZ002-009.

Lake Superior...
  Gale Warning until 8 PM EDT /7 PM CDT/ Wednesday for LSZ162.

  Gale Warning from 7 AM EDT /6 AM CDT/ to 8 PM EDT /7 PM CDT/
     Wednesday for LSZ240-241.

  Gale Warning from 10 PM this evening to 11 PM EDT Wednesday
     for LSZ242>244-263-264.

  Gale Warning from 2 AM to 11 AM EDT Wednesday for LSZ245>251-
     265>267.

Lake Michigan...
None.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning from 11 AM EDT /10 AM CDT/ to 8 PM EDT /7 PM CDT/
     Friday for LSZ162.

Lake Michigan...
None.

&&

$$

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