687
FXUS63 KMQT 080714
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
314 AM EDT Tue Jul 8 2025

.KEY MESSAGES...

- Seasonable temperatures persist in the Upper Peninsula for the
  work week.

- Rain showers and a few thunderstorms today, mainly across the
  west half. No severe thunderstorms are expected.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 312 AM EDT Tue Jul 8 2025

Early morning satellite imagery and RAP analysis reveal a low
amplitude trough across much of the Upper Midwest down the MS River
Valley. Low to mid-level warm advection is kicking off showers and a
few thunderstorms over western Lake Superior and just east of the
Bayfield Peninsula. Heading into the morning and early afternoon
hours, this region of precipitation will continue east into the
central UP as the attendant shortwave skirts overhead the Northern
Great Lakes. CAM guidance largely suggests this round of showers
petering out before reaching the east half. Behind this initial
wave, a weak sfc cold front will be the focal point for additional
scattered thunderstorms. 06z CAMs largely develop the second
round across the west-central UP, pushing into the central
counties before diminishing as night falls. Diurnally driven
instability will build upwards of 1500 j/kg during the afternoon
and with bulk shear pushing of 30-40 kts, cant rule out a
strong thunderstorms or two, though nothing severe is expected
at this time. As for precipitation amounts, 00z HREF highlights
60-80% probability for QPF amounts >0.25" west of Alger/Delta
counties. Given the scattered nature of afternoon thunderstorms
development, localized higher amounts will be possible.

Following into Wednesday, high pressure at the surface should keep
the forecast area dry through the day. Temperatures climbing into
the 70s are expected in locations removed from Lake Superior, with
lake-side communities only peaking in the mid to upper 60s.
Wednesday night temperatures look to cool into the upper 40s to low
50s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 312 AM EDT Tue Jul 8 2025

Quasi-zonal flow across the international border Wednesday breaks
down as ridging across middle North America amplifies in response to
a deep trough digging through the Rockies. As the ridge presses east
for the remainder of the week, a cutoff low off the California coast
will get pulled into the trough, resulting in split flow eventually
phasing over the Northern Plains or Great Lakes this weekend.

Lingering sfc high locks in dry weather through Thursday where
another day of widespread interior temperatures in the 70s, perhaps
low 80s interior west, and low 70s by Lake Superior, is expected.

The ridge axis presses into Upper Michigan Thursday followed by a
weak wave rolling atop the ridge Thursday night. Shower and
thunderstorm chances are co-located with diurnally driven instability
upstream in Minnesota, so any activity in western Upper Michigan or
Lake Superior overnight should be waning. Upstream Thursday into
Friday, a southern stream system, fueled by Gulf moisture, and a
robust shortwave moving through the Dakotas will begin to phase,
then lift northeast through the Midwest/Great Lakes region. Its
still unclear where the resultant surface low(s) will end up being,
but the rough approximation between the deterministic and ensemble
guidance packages suggest between Ontario north of Minnesota and
Wisconsin, before lifting north or northeast into Sunday. While
there are still differences on structure and location, fronts or
surface troughs with most options nearly all agree that precip will
lift through the forecast area Friday night into Saturday.
Instability appears to be lacking, with GEFS suggesting 20-30%
probabilities of 500-1000j/kg CAPE and similar, although slightly
higher, probabilities in the EC. While strong to severe
thunderstorms aren`t expected, thunder can`t be ruled out. Enhanced
by the Gulf`s influence, PWATs should climb to 1.5-2 inches (50-90%
chance per GEFS, GEPS, and EC ensemble systems), which alongside the
apparent modest synoptic forcing and lack of notable instability,
rainfall amounts under an inch look most likely (80-90% per LREF and
NBM). Precip will exit the region from west to east late Saturday,
perhaps returning late Sunday into Monday if a secondary shortwave
within the now-phase upper level low moves through the forecast area.

For temperatures, generally expect upper 70s to low 80s for a
majority of Upper Michigan on Friday, but more widespread cooler mid
70s for the weekend. Overnight lows also look to be mostly in the
mid 50s to low 60s.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1256 AM EDT Tue Jul 8 2025

VFR conditions will slowly deteriorate early this morning with the
onset of showers and thunderstorms from west to east. General trend
will be toward MVFR over the next several hours. Confidence is not
high enough to insert mention of IFR at this time, but it cannot be
ruled out with the increasing low level moisture. This low level
moisture will be slow to clear out, and do not expect a return to
VFR until late this afternoon/evening.

&&

.MARINE...
Issued at 312 AM EDT Tue Jul 8 2025

Winds 20 knots or less are expected through the rest of the week as
quasi-zonal flow sets up shop aloft. That being said, a low over the
Northern Plains lifts into the Lake Superior today, bringing showers
and a few thunderstorms to the area. Expect the rainfall to end by
evening as the low slowly travels southeastward with time.
Additional showers and storms could enter the far western lake
Thursday evening, although with convection being diurnally driven
expect the showers and storms to die out with time. As low pressures
phase over the Northern Plains and lift into northern Ontario from
Friday into this weekend, expect additional showers and
thunderstorms to develop over Lake Superior for that time period.

&&

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

&&

$$

SHORT TERM...BW
LONG TERM...JTP
AVIATION...TDUD
MARINE...BW/TAP