991
FXUS63 KMQT 221125
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
725 AM EDT Wed May 22 2024

.KEY MESSAGES...

- A Wind Advisory is in effect today due to wind gusts up to 50
  mph over the Keweenaw Peninsula and up to 45 mph along the
  remaining western Lake Superior shores of the UP.
- Waves of 6 to 8 feet along the shores of Lake Michigan to cause
  high risks of rip currents today.
- Another shortwave and low pressure system will bring another round
  of showers to Upper Mi late Friday into early Saturday.
- There may be more opportunities for light showers next week
  although model uncertainty leads to low forecast confidence on
  timing/extent at this point.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 351 AM EDT Wed May 22 2024

GOES-16 Water Vapor imagery and radar returns show that behind a
line of showers over the eastern UP, only isolated showers remain in
an otherwise dry slot. RAP Analysis shows a 989mb low over the
northwestern shores of Lake Superior progressing to the NNE. As the
low and parent trough move into northwest Ontario today, an 850mb
LLJ will be source of the most impactful weather over the UP today.
By 20Z, the 00Z HREF shows 50 kts at 850mb over the Keweenaw with 35-
45 kt over the remainder of the west half of the UP. Mixing will
allow for some of those winds to be transported to the surface in
the form of wind gusts over the Keweenaw up to 50 mph and gusts
across the rest of the west half of the UP to 35-45 mph. HREF and
EPS guidance suggests only around 10% probability of wind gusts
exceeding 58 mph over the Keweenaw, so the High Wind Watch is
cancelled. The HREF does indicate some 30% probabilities along the
western shores of the Keweenaw of 58 mph gusts, so coastal
communities such as Freda, Eagle River, and Eagle Harbor could see a
peak gust of that strength, but as far as widespread, sustained
gusts are concerned, gusts up to 45 mph are the main concern. The
Wind Advisory will continue for Gogebic and Ontonagon and will
expand to cover northern Houghton County and Keweenaw County. For
the remainder of the UP, gusts to 35 mph are expected today, which
is still pretty gusty, but no products are expected to be issued,
given the HREF has trended towards a more compact area of higher
winds over the west.

As the dry slot will continue to reside over the UP today, shower
chances will be low, however, the HREF does show isolated to
scattered showers supported by diurnal heating this afternoon, so
some low-end (15-30 percent) PoPs are left in, but impacts from this
should be minimal. For those willing to brave 55 degree water
temperatures over Lake Michigan, waves of 6-8 feet over the
nearshore waters of Schoolcraft County are leading to high chances
of rip currents, prompting a Beach Hazard Statement. Tonight, as
mixing becomes less efficient and the low pressure continues to lift
north and away from the UP, winds fall off and the weather is mainly
benign, with lows falling into the 40s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 507 AM EDT Wed May 22 2024

The extended forecast begins Thursday into Thursday with mostly dry
conditions under weak ridging.  The weak ridging will then give way
to the next shortwave emerging from the western CONUS trough which
will lift through the Northern Plains and Upper Great Lakes west
where a High Wind Watch and Wind Advisories were issued).s bringing
another round of showers to the U.P. late Friday into early
Saturday. While most of Saturday into Saturday night looks dry under
weak high pressure, model uncertainty increases out to Sunday and
beyond in the extended leading to lower forecast confidence although
it looks like there will still be showery periods into next week.

Beginning Thursday, the unusually strong storm system over western
Lake Superior early this morning will gradually weaken late tonight
into Thursday as it tracks ene from northern Ontario toward James
Bay. Increasingly confluent flow ahead of the mid-level ridge
building over the Northern Plains should lead to weak
ridging/subsidence and mostly dry conditions across the area on
Thursday. A few of the models hint at a subtle shortwave rotating
thru the area in the afternoon from the storm system over James Bay,
but any shower development from this weak wave should be sparse
given dry low-levels depicted in fcst soundings. Overall, should be
a nice day with highs across the interior mostly in the 70s with
readings in the 60s along Lake Superior.

By Friday, the focus shifts to the next shortwave emergieng
from the western CONUS mid-level trough. As this shortwave lifts
ne through the Plains and Upper Great Lakes increasing
isentropic ascent, 850 mb theta advection and moderate q-vector
convergence out ahead of the shortwave will lead to another
round of rain showers spreading w- e across the fcst area late
Friday into early Saturday.

By late Saturday morning, ridging and associated subsidence builds
in behind the shortwave leading to dry and seasonable temps for the
rest of the day with highs mostly in the 60s with a few cooler mid
50s readings near Lake Superior.

While models indicate weak ridging should hold on long enough to
keep Sunday dry, there is plenty of model uncertainty with what will
happen after that. The 00Z deterministic GFS and Canadian models
maintain mostly dry conditions through the first half of next week
suppressing a southern stream through Lower Great Lakes/Ohio Valley
and keeping the Upper Great Lakes mostly dry. Meanwhile, the ECMWF
the last couple of runs has trended toward a phased, deeper and
farther north system tracking over the Straits by 12Z Mon and the
latest 00Z run of the UKMET has also latched onto this idea. If this
solution verifies it will potentially be a much more impactful
system for the Upper Great Lakes into early next week with much of
the U.P. receiving significant soaking rainfall and possibly
heavy rainfall over the east half Sun night into Tue. Wraparound
moisture in the deformation zone, comma head of the deepening e
system would likely lead to the potentially heavy rainfall. This
deeper solution would also lead to more wind impacts with gales
likely over Lake Superior and windy conditions across much of
the U.P. Needless to say, model trends will be watched closely
in the coming days so stay tuned to possible forecast changes
into early next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 724 AM EDT Wed May 22 2024

Gradual improvement from MVFR to VFR is expected through this
morning and early afternoon at all 3 TAF sites. Gusty SW and W winds
this afternoon could peak as high as 40 kt at CMX, with 30 kt gusts
possible at IWD and SAW. As surface winds relax tonight, a
brief period of LLWS cannot be ruled out, but confidence is too
low to include in this TAF issuance. While some isolated -SHRA
is possible (10-20%) this afternoon, chances of precip were too
low to put in the TAF at this time. Overnight, skies scatter
out and eventually clear out along with winds falling to around
10 kt.

&&

.MARINE...
Issued at 507 AM EDT Wed May 22 2024

East-northeast winds appear to be already shifting southwest over
the western portion of Lake Superior early this morning as an
unseasonably deep low pressure system now over the MN Arrowhead will
continue to track north into Ontario today. Southwest gales can be
expected across Lake Superior with high-end gales to 45 knots and
maybe even a few storm force gusts to 50 knots expected over the
west half into north central sections. East half sections will
likely only see a brief period of southeast to south gales of 35 to
40 knots early this morning as a low-level jet continues to work
across the area before winds subside blo gales late this morning
into the afternoon. As the low gradually lifts north through Ontario
and weakens, winds will drop blo gales for west and north central
sections later this evening. The winds continue to diminish into
Thursday afternoon, when light winds of 20 knots or less return to
the area by evening. The period of light winds doesn`t last long
over the western lake as northeast winds will begin to ramp up to 30
knots late Thu night into Friday in advance of another low pressure
lifting from the Northern Plains towards Lake Winnipeg. Winds
diminish to 15 to 25 knots over the west half of the lake and
becoming southwest behind the low and the passage of its cold front
late Friday night into Saturday. Behind this system, expect light
winds of 20 knots or less across Lake Superior for the rest of this
weekend as high pressure ridging moves over the area.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Wind Advisory until 10 PM EDT /9 PM CDT/ this evening for
     MIZ001>003-009.

  Beach Hazards Statement through this evening for MIZ014.

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

  Gale Warning until 11 PM EDT this evening for LSZ242>244-263-
     264.

  Gale Warning until 11 AM EDT this morning for LSZ245>251-
     265>267.

Lake Michigan...
None.

&&

$$

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