639
FXUS63 KMQT 191949
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
349 PM EDT Sat Oct 19 2024

.KEY MESSAGES...

- Unseasonable warmth Sunday and Monday with highs in the 70s
  (~25 degrees above normal). Turning much cooler Wednesday, but
  only back to around normal for late October.

- Most days over at least the next 7 days will be dry. After
  today, next chance of showers is Tuesday night into Wednesday
  (50-80 percent chance), but significant rainfall is not
  expected.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 253 PM EDT Sat Oct 19 2024

A couple of weak shortwaves shearing northeastward and weakening
with time have been enough to force some light rain showers across
Lake Superior.  Most of the mainland U.P. has yet to see any rain
drops make it to the ground as sub cloud layer remains quite dry.
Isle Royale webcams from a bit earlier today did show some on and
off light rain so there is still a possibility of perhaps a
hundredth or two of rain over the far west and Keweenaw close to
Lake Superior though about 00Z this evening.  Temperatures tonight
will be similar to last night with lows bottoming out in the upper
30 where skies are clear the longest to mid 50s where clouds linger
longer and southwesterly winds stay the most persistent.

&&

.LONG TERM /SUNDAY THROUGH SATURDAY/...
Issued at 348 PM EDT Sat Oct 19 2024

Zonal flow over the Great Lakes kicks off the extend forecast noting
a mid level ridge over the southeastern U.S. and a closed low over
the southwest. Despite this, WAA is still expected bringing 850mb
temps on Sunday up to 11-12C. This will yield well above normal
temps for this time of year to the UP as highs are expected to peak
in the upper 60s to mid 70s! Sfc high pressure over the southeast
U.S. deflates during the day down to ~1028mb, but dry weather and
sunny skies persist in the UP. The ridging extending over the Great
Lakes keeps all precip well to our north as a weak trough tracks
east through northern Ontario. Mixing during the day will yield
breezy southwest winds, with model soundings indicating frequent
gusts between 20-30 mph over the west half of Upper MI; the east
will see gusts around 15-25 mph. Winds taper off Sunday night as we
decouple from the stronger winds aloft. Lows are expected in the
upper 40s to mid 50s.

Monday is anticipated to be another dry day in the UP as the mid
level closed low over the southwestern U.S. begins lifting northeast
to the Plains. Meanwhile, a shortwave over the Pacific Northwest
lifts northeast to the Canadian Prairie Provinces and a weak sfc low
tracks east out ahead of it to Manitoba. Mixing will not yield the
stronger winds as expected on Sunday, but drier RHs dropping down to
the mid 40s to 30s are expected. The interior west is the only
region that flirts with elevated wildfire conditions in the
afternoon, so will continue to monitor this potential with future
forecast packages. The NAM and GFS have tried to sneak in some light
QPF over the west during the later part of the day as a low level
shortwave/sfc trough lifts north over the area. The dry antecedent
airmass does not really support this solution and model soundings
show much to desire in the low levels (which only gets drier in the
afternoon). Expect sct/bkn clouds to lift north through the CWA
during the day. Some low chance PoPs are introduced Monday night as
a few stray light showers can`t be ruled out Monday night. These
likely will struggle to even wet the ground and are expected to
mainly be confined to out over Lake Superior.

A drier airmass begins to advect north into the UP Monday night,
suggesting some clearing in the cloud cover. Some high clouds are
likely given the approaching trough from the southwest. Lows are
expected in the upper 40s to upper 50s. With south to southwest
winds, downslope areas, especially with any cloud cover, will stay
warmer. But, low to mid 40s are possible in areas where skies clear
out. Dry weather holds through Tuesday afternoon as the cold front
approaches from the west. This will be the last well above normal
day with highs in the mid 60s to mid 70s, warmest in downslope areas
along the north.

The best shot at precip through the extended forecast arrives with
the cold front. A sfc low tracks northeast through northern Ontario
Monday night and Tuesday, moving toward Quebec for northern Quebec
by late Tuesday night ahead of a mid level shortwave trough. While
there is still some spread in the guidance on the sfc low track
Tuesday onward, there is pretty good agreement on the cold front
timing. This system brings a cold front to the west around 8pm EDT
Tuesday which pushes southeast across the UP through mid Wednesday
morning. A mid level trough then tracks east-southeast over the area
Wednesday into Wednesday night. With the passing front, ~0.1" to
0.25" of rain is expected. 850 temps drop to between -4C and -7C,
yielding delta-ts supportive of some northwest flow lake effect rain
showers that continue into Thursday.

Medium range guidance has some agreement on a shortwave trough
riding southeast through the Upper Great Lakes sometime Thursday
night/Friday. Arrival time has some spread yet, but ensemble
probabilities indicate this will not be a big precip producer with
only a 10-30% chance of 0.1" or more rain. This makes sense given
PWATs struggle to even reach 0.6" to 0.7". Otherwise, temperatures
behind the cold front Tuesday night drop back down closer to normal,
but are expected to return above normal for next weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 136 PM EDT Sat Oct 19 2024

VFR conditions are expected at all 3 TAF sites through the period. A
weakening disturbance will bring some VFR cigs and a few sprinkles
or light showers to both KCMX and KIWD this afternoon and early
evening before skies clear again overnight. Winds will be from the
southwest at all 3 locations with some gusts over 20mph possible at
KIWD and KCMX by mid morning on Sunday.

&&

.MARINE...
Issued at 348 PM EDT Sat Oct 19 2024

South to southwest winds are expected to remain below 20 kts through
this evening due to a decaying cold front. Southwest winds increase
tonight, gusting to 20-25 kts by Sunday morning. Winds on Sunday
over the eastern third of the lake drop to less than 20 kts while
the western two thirds sees gusts to 20-30 kts, strongest winds are
expected between Thunder Bay, Isle Royale, and the Keweenaw
Peninsula. Stability over the lake should prevent any gale force
gusts across the lake. Winds quickly fall below 20 kts early Sunday
night, gradually veering overnight to become east for Monday. Winds
on Monday will remain mainly below 15 kts. Winds veer southwest
Monday night, but continue to remain below 20 kts. Southwest winds
gusting to 20-25 kts are expected on Tuesday as another cold front
approaches from the west; a few gusts to 30 kts are possible near
Isle Royale, particularly between the island and Thunder Bay.
Stronger winds to 20-30 kts will follow passage of the cold front
Tuesday night. Ensemble guidance points toward a 30-60% chance of
northwest gales late Tuesday night through Wednesday over the east
half of the lake as much colder air surges through.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...MZ
LONG TERM...Jablonski
AVIATION...MZ
MARINE...Jablonski