Sagola, Michigan Weather Forecast Discussion

474
FXUS63 KMQT 081102
AFDMQT
Area Forecast Discussion
National Weather Service Marquette MI
702 AM 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 (>75% chance) across
  much of the western UP tonight through Tuesday. There is a
  Marginal Risk (level 1 of 4) for flash flooding.
- Strong S to SW winds upwards of 30 mph ramp up late tonight
  (>75% chance), with gusts upwards of 40 to 45 mph possible
  (25-50% chance) along the central and eastern Lake Superior
  shoreline Tuesday morning.
- A warming trend is set for this week with daytime high temps
  climbing back into the 60s to low 70s and overnight lows
  averaging near 50.
&&
.SHORT TERM /THROUGH TUESDAY/...
Issued at 445 AM EDT Mon Sep 8 2025
Early morning GOES Satellite imagery and RAP mesoA reveals upper
level ridging overtop much of the central CONUS on the western flank
of a departing trough. This is supporting ~1026mb sfc high pressure
centered across the lower Great Lakes, meandering eastward towards
the N Appalachians and eastern seaboard. A very subtle embedded
shortwave within the NW flow aloft is moving high clouds overhead
Lake Superior and the UP. Through this afternoon, relatively benign
weather is expected as the departing sfc high keeps things dry and
return flow on the backside of the high sends high temps back into
the upper 60s to near 70 area wide.
Potentially high impact weather makes an entrance tonight through
Tuesday as mid-level troughing emanating off Rockies combined with a
sharp shortwave diving SE into the region from Sask/Manitoba will be
the culprit for heavy rainfall and strong winds. Modest isentropic
ascent ahead of a warm front and strengthening 35-45 kts LLJ will
provide the necessary forcing for shower and thunderstorm
development across MN/WI before expending in coverage to the western
UP tonight into the early morning hours of Tuesday, further
expanding eastward through Tuesday morning/afternoon. Thunderstorms
are not expected to be severe, with bufkit thermal profiles mainly
depicting skinny elevated instability atop a low level inversion.
What is concerning is potential for heavy rainfall occuring across
much of the western UP, potentially as much as 3-5" by Tuesday
afternoon if training convection occurs. Heavy rainfall ingredients
don`t quite scream flash flooding given warm cloud depths just shy
of 10k ft and fast storm motions, but PWAT value climb back above an
inch to near 1.25" (the 75th to 90th percentile of NAEFS climo for
this time of year), and localized ascent provided by a strong LLJ
overhead the frontal boundary may aid in the overall heavy rain
potential. Model guidance has ramped UP precipitation values over
the last 24 hours, with NBM 75-90th percentile suggesting a
widespread 1-2" by Tuesday night. 00z HREF guidance may better hint
at the heavy rain potential, however, depicting pockets of 2-4" in
the 24hr PMM QPF. Global ensembles are a hit or miss as the 00z Euro
ENS only suggesting a 50-70% chance for 1" of rain across portions
of the west and central UP through Tuesday night, and the GEFS
suggesting high probability for 0.5" but no chance for 1". For
these reasons, WPC has opted to include a Marginal Risk (level 1
of 4) for flash flooding across the west half of Upper Michigan
or this timeframe.
The next hazard stems from the stout LLJ ripping overhead. CAMs have
trended 950-850mb LLJ winds upwards of 35-45 kts as it noses into
the UP by 00z Tuesday. While maybe a bit overdone since an
increasing low-level cap may hinder mixing down the strongest gusts,
the latest HREF points towards widespread 25-35 mph S to SW wind
gusts ramping up late tonight into early Tuesday morning. Gusts may
be locally enhanced as they run down the typical downsloping
locations of the central and eastern UP Lake Superior shorelines.
While still a bit skeptical, the HREF suggests a 60-90% chance for
downsloping gusts >45 mph along the Marquette and Alger county
shorelines Tuesday morning. Have opted to hoist Gale Watches
for the nearshore LS zones and open waters of eastern LS. Should
the trend hold, wind headlines may be needed.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 445 AM EDT Mon Sep 8 2025
By midweek, deepening midlevel low pressure will be spinning over
the Pacific Northwest and Quebec, with ridging recovering atop the
central CONUS. This will keep the U.P under a northwest to westerly
upper level flow through the latter half of the week while surface
high pressure expands over the region, favoring a return to mainly
dry weather for the rest of the work week. Ridging breaks down into
next weekend with PoPs returning to the forecast. Temperatures trend
warmer this week, with highs in the 60s to lower 70s.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 702 AM EDT Mon Sep 8 2025
VFR conditions are expected to prevail today into this evening as
the cloud deck over the central U.P. this morning is expected to
clear out in an hour or two. However, as a warm front approaches the
area today, expect high to mid-level cloud cover to begin enveloping
the area late this afternoon through tonight, with rainfall and a
few elevated thunderstorms moving overhead across the TAF sites late
tonight. With the warm front overhead tonight, expect a LLJ to bring
LLWS conditions to each of the terminals, although some gustier
south to southwesterly winds may be able to mix down to the sfc from
time to time. In the heavier rain showers and thunderstorms tonight,
we could also see conditions deteriorate down into MVFR or lower
occasionally too.
&&
.MARINE...
Issued at 445 AM EDT Mon Sep 8 2025
Winds gust up to around 20 knots between Isle Royale and the
Keweenaw this morning before briefly falling back down to less than
20 knots by this afternoon. However, a shortwave low moving through
the lake tonight is expected to bring south to southwesterly winds
of 20 to 30 knots back over the lake tonight into Tuesday. Over the
eastern half of the lake, there is around a 25-50% chance for gales
up to 35 knots over the open waters (mainly over the higher
platforms). Meanwhile, along the southern shoreline from around the
Huron Islands to just east of Grand Marais, Michigan, there is
around a 30 to 60% chance for downsloping gales up to 35 knots
tonight into Tuesday. Therefore, due to the potential for mixing
into strong LLJ aloft (especially near the downslope areas), a Gale
Watch has been issued for tonight until early Tuesday afternoon. In
addition to the potential gale conditions, some showers and storms
associated with the shortwave low are expected to move over the lake
tonight through Tuesday night; thankfully, no severe weather is
expected with this low. Once the low passes through the lake Tuesday
morning, expect the winds to die-down to 20 knots or less again by
the afternoon hours, with winds remaining light to the end of the
work-week as high pressure ridging settles over the Upper Great
Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Gale Watch from this evening through Tuesday afternoon for
     LSZ248>250-266.
Gale Watch from late tonight through Tuesday afternoon for
     LSZ251-267.
Lake Michigan...
None.
&&
$$
SHORT TERM...BW
LONG TERM...BW
AVIATION...TAP
MARINE...TAP

NWS MQT Office Area Forecast Discussion