Chassell, Michigan Weather Forecast Discussion

629
FXUS63 KMQT 081905
AFDMQT
Area Forecast Discussion
National Weather Service Marquette MI
305 PM EDT Mon Sep 8 2025
.KEY MESSAGES...
- Dry weather persists through this afternoon before a warm front
brings showers and thunderstorms tonight into Tuesday.
- Heavy rainfall exceeding 1" is possible (30-60% chance) across
much of the western UP tonight through Tuesday. There is a Marginal
Risk (level 1 of 4) for flash flooding.
- Gusty SW winds develop late tonight into Tuesday morning, with 30-
40 mph gusts expected near the Lake Superior shoreline. A few gale
force gusts are possible in the nearshore waters.
- High temps mainly in the 60s and 70s expected for this week.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 305 PM EDT Mon Sep 8 2025
Upper Great Lakes region remains under low-amplitude northwest flow
aloft, leading to tranquil conditions this afternoon. High clouds
are building in ahead of the next system of note, which will impact
the region tonight into Tuesday. Midlevel flow will flatten with a
low-amplitude shortwave trough shifting east from the northern
Plains into the Great Lakes tonight. A southwesterly low-level jet
will increase substantially ahead of this feature, reaching
magnitudes of 40-45 kt in the 925-850 mb layer per recent RAP
guidance. Moisture will increase along the LLJ accordingly, with a
plume of PWATs reaching up to 1.25 inches per the 00Z NAEFS, which
corresponds to around +1 sigma. An area of rain and embedded
thunderstorms is expected to develop this evening along the nose of
the LLJ in the MN arrowhead or western Lake Superior, pushing
eastward into the western UP overnight. The moisture content, along
with weak elevated instability (250-750 J/kg per the 12Z HREF), and
potential for storm motion to align with the zonally-oriented
forcing points to a heavy rainfall threat primarily over the western
UP tonight into early Tuesday. This is supported by 6-hour localized
probability matched mean (LPMM) values of 2-4" in spots late tonight
into early Tuesday, suggesting local amounts in this range are
possible, while basin-average totals are likely to be in the 0.75-
1.50" range. The magnitude of possible rainfall along with the fact
that antecedent conditions have been rather wet (14-day departures
of 150-250% of normal and CREST soil moistures in excess of 50
percent) suggest a localized flash flood threat with any training
storms that may develop. Outside of the rainfall, regions to the lee
of the higher terrain on the shorelines of Lake Superior in the
central/eastern UP could get rather gusty overnight with wind gusts
of 30-40 mph possible.
For the rest of Tuesday, showers and a few embedded thunderstorms
likely continue and shift into the southern and eastern UP. Although
the forcing will not be as good as overnight with a veered LLJ,
another shortwave approaching from the west will result in some
broad lift, and the 1.25 inch moisture plume will continue to be
over the region. Temps will be near to slightly below normal in the
mid-60s to low 70s.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 305 PM EDT Mon Sep 8 2025
Troughing digs further southward Tuesday night/Wednesday,
encompassing much of the Upper Great Lakes. The associated 1+ inch
PWAT plume lingers over the area, so showers may linger into
Wednesday, gradually dissipating with time. Omega block pattern
emerges for mid to end of the week with ridging building into the
Plains states. At the surface, high pressure will build into central
Canada and the upper Great Lakes, resulting in mainly dry weather
for later Wednesday into Friday. The ridge and high pressure
shifting east will allow for a warming trend by Friday/Saturday;
however, potential for an upper low dropping down from central
Canada flattening the ridge will open the door for shower potential
by Friday night into Saturday. Cluster analysis shows about 30% of
ensembles showing this trough, while the remainder keep the ridge
around in some fashion, which would result in continued mainly dry
weather.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 154 PM EDT Mon Sep 8 2025
VFR conditions to prevail, yet, through this evening. However,
periods of MVFR will then be possible after that through the end of
the TAF period as a warm front brings showers and thunderstorms to
Upper Michigan. Best chances for any thunderstorms will be in the
Tue 00-06Z time frame, but rainfall will be persistent throughout
the TAF period. IFR cannot entirely be ruled out in some of the
heavier downpours, but confidence remains too low at this time to
insert mention. In addition, LLWS will be a threat at all terminals
tonight as a LLJ accompanies the front. And, southwesterly surface
winds will gust to 25 to 30 kts.
&&
.MARINE...
Issued at 305 PM EDT Mon Sep 8 2025
A low-level jet will strengthen tonight and bring gusty winds to the
waters. Overlake stability is expected to result in gusts around 30
kt at 10m forecast heights, although gales are certainly possible on
higher observing platforms. Some downsloping could result in a few
gale force gusts along the shorelines of the central and eastern UP
tonight into Tuesday morning as well. Showers and embedded
thunderstorms are also expected during this time frame. Winds should
die down Tuesday night, with mainly less than 20 knots expected
through the end of the week as high pressure builds in.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from 8 PM EDT this evening through Tuesday
     afternoon for LSZ248>250-266.
Gale Watch from 2 AM EDT Tuesday through Tuesday afternoon for
     LSZ251-267.
Lake Michigan...
None.
&&
$$
SHORT TERM...Thompson
LONG TERM...BW
AVIATION...Thompson
MARINE...Thompson

NWS MQT Office Area Forecast Discussion