573
FXUS63 KMQT 041151
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
751 AM EDT Sat May 4 2024

.KEY MESSAGES...

-Rain overspreading the UP from west to east today as a low
 pressure system approaches from the central Plains.
-The UP remains under the preferred path for low pressure
 systems, with multiple notable features passing through the
 next week.
-In between systems, dry conditions will be expected, though
 mostly low winds and antecedent rainfall should broadly limit
 fire concerns.

&&

.SHORT TERM /TODAY/...
Issued at 454 AM EDT Sat May 4 2024

Increasing clouds continue to stream into western portions of Upper
Michigan early this morning per latest water vapor imagery.  As a
low pressure system continues its northeastward propagation toward
the UP from the central Plains, that cloud cover will continue to
overspread the eastern half of the forecast area as well today. And,
an uptick in isentropic ascent will commence over the western
counties by mid-morning as well, resulting in 30-50% rain chances by
Sat 15Z in the Ironwood area.  Just like the cloud cover, these rain
showers will make their way eastward through the morning and
afternoon hours with increasing rain probabilities over much of
Upper Michigan by late afternoon.  Nonetheless, the eastern third of
the UP should have enough time to warm into the low 70s, unlike the
western third which will struggle to reach 60 degrees with earlier
onset of rain. Currently, temperatures across the area are ranging
from the upper 30s across the interior to as high as the upper 40s
to mid 50s along the Lake Superior lakeshore.

&&

.LONG TERM /TONIGHT THROUGH FRIDAY/...
Issued at 436 AM EDT Sat May 4 2024

Starting tonight, a broad trough will expand over the Upper Midwest
and central Canada with a ridge over the eastern U.S. coast and a
closed low over the western U.S. coast. A shortwave riding the
middle trough will be progressing eastward over the U.P. with
another shortwave not long behind it over Manitoba. The associated
cold front finish progressing east across the U.P. by Sunday
morning, bringing a line of showers eastward as well as a brief
period of northeast gusts to 20-25 mph; a few rumbles of thunder are
possible mainly earlier in the period. Lows overnight are expected
in the mid 30s to mid 40s, warmest east where the cloud cover is
expected to hold on the longest.

The second shortwave passes just north of Lake Superior on Sunday,
but no precip is expected as sfc high pressure builds in over the
Upper Great Lakes. This should see cloud cover diminish, light
winds, and highs in the mid 50s to mid 60s; warmest south central.
Mixing increasing in the afternoon, stronger over the interior west,
will bring RHs down around 40% in the east/Keweenaw with near 30-35%
in the interior west. No fire weather concerns are expected at this
time. With mid level ridging moving east over the Great Lakes and
high pressure shifting to expand over the entire basin, the quiet
weather continues with lows in the mid 30s to low 40s. Meanwhile,
the closed low will have made it onshore and moved east over the
Rockies, beginning to open up into a trough and take on a negative
tilt.

By Monday morning, the trough will be situated just over the lee
side of the Rockies. High pressure means another dry day with better
mixing up to ~850 mb. Stronger winds mixing down from aloft are not
going to be an issue, but lower dew points will be. Minimum RHs are
expected around 30-35% in the afternoon/evening hours. With highs in
the upper 50s to low 70s, cooler by the lakeshores, we flirt with
borderline elevated fire weather conditions. Will want to monitor
these conditions in future forecast packages. The trough is expected
to pivot northeast over the Plains through Monday night supporting
sfc low cyclogenesis, but the U.P. stays dry yet. Monday night will
be warmer than the previous night with temps only settling into the
40s, warmer in the west as clouds increase ahead of the next system.

Chances for showers increase in the far west on Tuesday with
increasing q-vector convergence, but likely will hold off until late
morning/early afternoon when the trough begins to develop back into
a closed low over the northern Plains. PVA over our region increases
at this point into Wednesday morning as a shortwave cycles around
the low, eventually passing northeast over the Upper Great Lakes. An
approaching left exit region of the upper level jet also looks to
support additional cyclogenesis over the Central Plains Tuesday
night. This second sfc low then lifts northeast on Tuesday, crossing
northeast over the Great Lakes Tuesday night resulting in an uptick
in PoPs Wednesday night. Meanwhile, the stronger sfc low associated
with the mid level low will spin over the Northern Plains. With the
given spread in the guidance, opted to leave the NBM PoPs Tuesday
onward. There is a chance for thunderstorms on Tuesday and
Wednesday, but confidence remains low at this point given the spotty
instability noted in the guidance; best chances are on Tuesday when
the mid level lapse rates and bulk shear are higher.

Slight chances for showers gradually diminish through the end of the
work week as we begin to see a pattern shift. Longer range ensemble
guidance hints at positive 500 mb height anomalies over the western
U.S. with negative height anomalies moving toward the east coast
toward the latter part of May. This means less moisture from the
Gulf of Mexico to support precip chances and cooler northwest flow
over the Great Lakes. The drier trend is captured well by CPC precip
outlooks out to 3-4 weeks with a cooler pattern more within the next
8-14 days.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 750 AM EDT Sat May 4 2024

VFR conditions will slowly deteriorate to MVFR and possible IFR
starting this morning at IWD as rain overspreads Upper Michigan from
west to east.  CMX and SAW will have later rain onset times though
and thus VFR conditions until late afternoon/early evening.  At that
point, look for MVFR/IFR conditions at those TAF sites as well
into tonight.

&&

.MARINE...
Issued at 436 AM EDT Sat May 4 2024

Southwest winds this morning become northwest mid morning over
the west half of Lake Superior as a weak low pressure lifts
northeast into the region. Winds across the rest of the lake
turn northeast behind a cold front this evening as the low lifts
northeast into northern Ontario. The eastern portions of Lake
Superior could briefly see some northwest wind gusts up to 25 kt
tonight into Sunday morning. As high pressure settles over the
lake Sunday and Monday, winds will be below 20 kt until Monday
afternoon. A strong low pressure system over the Northern Great
Plains will cause gusty northeasterly winds to funnel towards
Duluth Harbor to around 20-25 kts monday afternoon into Monday
night. Meanwhile, a second weaker low pressure develops over the
Central Plains, lifting northeast toward the Upper Great Lakes
on Tuesday. The track and timing of this secondary low is still
not totally solid, but east winds to 20-30 kts are likely
Tuesday into Tuesday evening as it moves through the Great Lakes
Basin. Probability of Gales remains low at this time. (<20%
chance of winds exceeding 34 kts). Winds look to hold around
15-25 kts through the rest of the work week.

&&

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

&&

$$

SHORT TERM...TAP
LONG TERM...Jablonski
AVIATION...TDUD
MARINE...Jablonski