657
FXUS63 KMQT 231107
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
707 AM EDT Mon Jun 23 2025

.KEY MESSAGES...

- A hot and humid airmass is expected over mainly central Upper
Michigan today ahead of the cold front moving in. Those sensitive to
heat, especially those without effective cooling and/or hydration,
may be impacted.

- A Slight Risk (category 2 out of 5) of damaging severe winds and
hail exists across the area for today as a cold front pushes
through, though temperatures return to normal following the front.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 312 AM EDT Mon Jun 23 2025

GOES water vapor imagery shows dry air in the lower levels keeping
convection at bay and skies mostly clear across our area early this
morning as a cold front is moving through Minnesota. With the warm,
moist air still overhead this morning, temperatures have struggled
to lower even despite the mostly clear skies; as of 240 AM EDT this
morning, several spots in the interior western half of the U.P. have
failed to get below 80 degrees. While we can expect temperatures to
drop a few more degrees before the sun rises today, lows are still
expected to only get down into the mid 70s across much of the
interior west and central this morning.

As the cold front begins to push into the far west late this
morning, we could see a few scattered showers and storms develop and
continue eastward throughout the day. However, confidence in
unbroken/unceasing convection along the cold front today has greatly
diminished, as the latest HRRR runs (which have handled the lack of
convection over our region the best this morning) has much less
convective coverage across our area late this morning through this
evening in comparison to previous runs of itself and other model
guidance. With bulk shear and hodographs being not all that
impressive (0-6 km bulk shear around 30 knots), the large amount of
sfc-based CAPE is going to have to compensate in order to severe
weather to occur; that being said, different model guidances do show
CAPE in the 1 to 2 thousand J/kg range, so there is plenty of energy
in the atmosphere to work with, and the cold front will be a
suitable forcing mechanism for air parcel uplift; as of the time of
this writing, SPC still has a Slight (2 out of 5) risk for severe
weather over us today, mainly for severe winds followed by severe
hail. Thus, we still could see a couple of strong to potentially
even severe storms today, particularly over the central and east
where/when instability will be better (front expected to move
through the central and east this afternoon to early evening).
Again, though, confidence in the convection occurring over us today
is actually decreasing as the latest runs, particularly of the HRRR,
are now showing the area being mostly dry now as the cold front
moves through. While we may see some post-frontal redevelopment of
showers and a thunderstorm or two over the south central and east
this evening, expect the rest of the area to remain dry for tonight,
with the far east and south central looking to finally become rain-
free by Tuesday morning.

While we can expect temperatures to soar once again ahead of the
cold front today, expect much cooler and more normal temperatures
behind the front as we cool into the 70s over the west by late this
afternoon. The south central looks to hold onto the hot and humid
conditions the longest, with Heat Indexes over 95 degrees possible
over a few interior spots this afternoon. As for highs, expect
temperatures to get to around 90 over the central U.P. this
afternoon before the cold front begins to cool things down late this
afternoon. While we can expect gusty southwesterly winds at the sfc
today ahead of and along the front, by tonight expect the winds to
become quite calm as zonal flow aloft and sfc ridging build into the
region. Expect the much needed relief from the heat to hit Upper
Michigan tonight, with lows finally dropping down into the 50s
across the area, except the lower 60s over the south central. On
Tuesday, with synoptic forcing being very weak, expect the lake
breezes to be the main driver in regards to high temperatures and
winds; high temperatures are expected to be around to maybe even
slightly below normal on Tuesday, with the 60s expected near Lake
Superior and the 70s seen in the interior areas.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 312 AM EDT Mon Jun 23 2025

Expansive 500mb ridging will remain over the US Southeast by midday
Tuesday, but some hints of a shifting pattern will begin to emerge,
first in that the flow over the Rockies becomes split, with ridging
over the Canadian Rockies and deep troughing remaining over the US
Rockies. Throughout Wednesday into Thursday, a 500mb cutoff low
moving into Florida, helping erode the blocking ridge over the
eastern CONUS. With the split flow over the Rockies also moving east
and deamplifying, flow goes quasi-zonal, allowing for the former
Rockies troughing feature to shift through the Great Lakes, bringing
with it disturbed weather. While the global deterministic and
ensemble suites diverge significantly for the end of the week into
next week, there are some early indications of a prominent trough
moving into the region sometime in the late Sunday to early Tuesday
timeframe which could bring yet another round of disturbed weather.
In the wake of today`s cold front, the temperatures for the midweek
period are forecast to be close to normal (perhaps a few degrees
cooler) with a warming trend late in the week into the weekend.

Chances of rain begin to creep up Wednesday as a subtle impulse
riding the upper ridge forces precipitation over the area. The Gulf
connection persists with flow aloft arcing from the Texas/Louisiana
coastline to the Great Lakes, so moisture will be plentiful, though
somewhat nebulous forcing and cooler surface temperatures limiting
instability will keep most thunderstorm chances at bay. Current LREF
mean QPF for the Wednesday and Wednesday night period is a
widespread one to two tenths of an inch, with a "worst case
scenario" 90th percentile of around a half inch.

Thursday is when the more pronounced troughing that used to be over
the Rockies arrives in the Great Lakes. Instability is still fairly
limited, but with more robust forcing, expect a few thunderstorms
(30 percent chance, highest in the south). Stronger forcing with
PWATs pushing 1.5 inches will result in higher QPF, with the LREF
showing chances of 2 inches of rain at about 10 percent by the end
of the day Thursday. Everyone is likely to get at least a soaking,
as chances of a half inch of rain is 40-60 percent (highest south,
lowest Keweenaw). The WPC is watching the UP for flash flooding
potential, giving a Slight Risk of Excessive Rainfall (category 2 of
4, or around 15 percent).

Heading into the weekend, some slight chance PoPs (15-25%) linger in
the forecast due to the increasing spread in solutions, but
generally drier conditions are expected as ridging in the wake of
the trough moves over the UP. Attention then turns upstream to the
next trough dropping down from Canada sometime in the Sunday-Tuesday
range, which could bring with it showers and thunderstorms. In the
meantime, a warmup is expected for the weekend, with the NBM
deterministic forecasting 980 degree highs for most by Sunday.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 706 AM EDT Mon Jun 23 2025

Gusty SW winds will be seen ahead of a cold front moving through
late this morning through this afternoon across the TAF sites. While
gusty W winds will be seen along and immediately behind the cold
front, winds are expected to calm down tonight as high pressure
builds in at the sfc and zonal flow sets up in the mid levels.
Expect generally VFR conditions to dominate. However, showers and
storms associated with the cold front`s passage could drop down
conditions to MVFR or lower; confidence on the exact timing of the
convection is only moderate at this time as some models have the
area getting largely skunked (a.k.a. no rainfall). That being
said, with convection currently over western Lake Superior and
northern WI this morning, moderately (40-60%) confident on the
timing of potential showers and storms moving through today.

&&

.MARINE...
Issued at 312 AM EDT Mon Jun 23 2025

Southerly winds of 20 to 30 knots over the eastern lake early this
morning develop off of the southern shoreline near the western U.P.
before dawn as a cold front (currently over Minnesota) continues
eastwards over the lake today. As the front pushes through, expect
the winds to veer more westerly today to 20 to 30 knots; while not
widely expected, a rogue westerly gust or two up to 35 knots cannot
be completely ruled out (the latest HREF shows up to a 30% chance
along the northern shore of the Keweenaw Peninsula this afternoon).
In addition, a few showers and storms could be seen along the front,
but the chances for convection have decreased over the past several
hours (see the latest Short Term discussion for additional details).
As more zonal flow aloft and sfc ridging build over the region
tonight into Tuesday, expect the winds to lighten to 20 knots or
less by this evening, with thunderstorm chances ending over Lake
Superior as well. Winds appear to remain light the rest of the week,
although chances for thunderstorms do look to return around
Thursday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Beach Hazards Statement through this evening for MIZ014.

Lake Superior...
  Dense Fog Advisory until 11 AM EDT /10 AM CDT/ this morning
     for LSZ162-263.

Lake Michigan...
None.

&&

$$

SHORT TERM...TAP
LONG TERM...GS/TAP
AVIATION...TAP
MARINE...TAP