598
FXUS63 KMQT 212356
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
656 PM EST Thu Nov 21 2024

.KEY MESSAGES...

- Scattered rain showers continue over the north tonight
  through Friday.

- Light lake effect rain/snow showers are possible in the east
  half of the U.P. Saturday. Little to no accumulations are
  expected.

- Active weather with chances for accumulating snow return next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 322 PM EST Thu Nov 21 2024

Afternoon satellite imagery and RAP analysis show the sfc low has
made it just south of central Lake MI. Aloft, the mid level low is
analyzed over Lake Erie and OH with a ridge building in over the
Plains. Satellite imagery also highlighted some well defined
gravity waves earlier this afternoon in the low cloud deck near the
MN Arrowhead shores of Lake Superior. This is where some weak sfc to
850 mb CAA, low level fgen, and pressure rises resulted in northwest
katabatic winds. A few ship observations came in with storm force
winds gusting into the low to mid 50 kt range! SAR wind data also
shows that these winds extended into the northern open waters of
LSZ162. Outside the marine impacts, pressure falls this morning and
the tight pressure gradient resulted in northerly wind gusts up to
35 to 45 mph in the north half of the UP with 58 mph recorded at
Houghton County Memorial Airport. This ended up causing some power
outages this morning, but winds have already begun to weaken this
afternoon. North winds have fallen below 15 mph over the eastern
half of the UP with gusts still in the 15 to 25 mph range over the
west. North winds of 10 to 20 mph are expected for tonight.

Numerous showers have continued to dominate the central UP with
scattered showers over the west and isolated shower to dry
conditions over the east. Some clearing is even observed on
satellite over the Lake MI shores of Upper MI and northern Lower MI.
The sfc low is progged to descend over the rest of Lake MI into this
evening, dissipating tonight as the mid level low spins toward the
Atlantic Coast. This yields a eastward shift in the dominating band
of showers before some dry air moves in from the north. Model
soundings show the drier airmass intruding above the the 5-7 kft
level, diminishing shower coverage and overall QPF. That said,
scattered upslope and lake enhanced showers are expected tonight
over the north. An additional few hundreths to 0.15 inches are
expected over the western 2/3 of Upper MI this afternoon through
tonight. Up to 0.6" of additional rain is forecasted over portions
of Baraga and Marquette Counties aided by the upslope flow; most of
the QPF is expected to fall during the next 6 hours. Overall, wet
snow and rainfall over the past 24 hours has brought around 0.5 to 2
inches of liquid precip which should help improve drought conditions
across the UP.

Otherwise, temps currently in the upper 30s to mid 40s are expected
to settle into the mid 30s to low 40s tonight.

&&

.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 334 PM EST Thu Nov 21 2024

Mostly quiet weather returns this weekend as ridging over the west-
central CONUS nudges into the Upper Great Lakes this Friday,
however, we wont completely dry out as northerly flow over Lake
Superior and weak lake enhancement provide some light rain/drizzle
through the day. Favored upslope locations in the central U.P. could
pick up a few hundredths, otherwise not expecting anymore widespread
showers. Some light snow is possible in the Michigamme Highlands as
temperatures head toward freezing Friday night. Upstream, a
shortwave diving southeast across northern Ontario Saturday kicks
off a weak surface low over James Bay. Though the better synoptic
forcing remains to our north, a shot of colder 850mb temps near -8
to -10C will provide enough lake induced instability for showers in
the east half of the UP given northwest flow. Lake effect showers
will likely start off as rain but transition to light snow as wet-
bulbing processes take effect and colder air filters in the column.
Little to no snow accumulation is expected, though some heavier
showers could provide a light dusting for Alger and northern Luce
counties in the evening.

A brief period of height rises on Sunday will put an end to lake
effect showers and our attention then turn to a deepening trough
across the Plains digging into the Upper Midwest Monday into
Tuesday. Current deterministic guidance and their respective
ensemble packages are still in disagreement on the placement of the
surface low and associated snowfall/gusty winds. Euro ensemble is
much further north and faster with a surface feature in the vicinity
of the UP/Lake Superior by Monday morning, while GEFS low locations
are weaker and move the low through lower Michigan late Monday into
Tuesday. Ensemble meteograms only show light snow accumulations up
to a few inches by Tuesday evening.

Looking towards Thanksgiving, ensembles are in agreement in a period
of negative 500mb anomalies across the central US, supporting active
weather with chances for accumulating lake effect snow in the Great
Lakes region and possible hazardous travel conditions during the
late week holiday timeframe.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 655 PM EST Thu Nov 21 2024

The coverage of rain showers will diminish across the area this
evening; however, mainly IFR conditions are expected to persist
across the area through the TAF period. For tonight, there is ~30%
chance for showers streaming off Lake Superior, but best confidence
in showers is at SAW. Northerly winds will diminish through this
evening, becoming mainly 10-20 kt for tonight persisting into
Friday.

&&

.MARINE...
Issued at 334 PM EST Thu Nov 21 2024

Surface low pressure near 998 mb is making its way down the
long axis of Lake Michigan this afternoon, further weakening as
it continues southeast into Indiana this evening. With the
pressure gradient lessening over Lake Superior, widespread
northerly gales are expected to diminish through the afternoon;
however, localized terrain driven storm force gusts upwards of
55+ knots were observed by passing ships just offshore of the
Minnesota Arrowhead just before Noon EST, prompting a short-
fused upgrade to Storm Warnings in far western Lake Superior.
These enhanced gusts should continue to dwindle below gale force
criteria by at least midnight tonight.

Winds turn out of the north-northwest Friday gusting to near 25
knots over the east-central lake, then continue diminishing below 20
knots by Saturday evening, calming further into Sunday. Gusty winds
return late Monday into Tuesday as a low pressure system is forecast
to impact Upper Michigan. As of this forecast package, confidence is
low (~40%) on the low pressure center location and strength. A low
closer to the UP could bring northwest gales to Lake Superior while
a more distant low through Lower Michigan could keep winds marginal.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Warning until 7 PM EST /6 PM CST/ this evening for LSZ162.

Lake Michigan...
None.

&&

$$

SHORT TERM...Jablonski
LONG TERM...BW
AVIATION...RM
MARINE...BW