615
FXUS63 KMQT 180924
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
524 AM EDT Tue Jun 18 2024

.KEY MESSAGES...

-Hot and humid today with southerly winds of 10-20 mph, gusting
 to 30+ mph. Showers/storms returning this evening from the
 west.

- Multiple rounds of showers and thunderstorms expected this
week. Strong to severe storms possible tonight into Wednesday.

- Potential heavy rain event this weekend.

&&

.SHORT TERM /TODAY/...
Issued at 500 AM EDT Tue Jun 18 2024

Scattered showers with embedded thunder continue to drift across
northern and southern portions of Upper Michigan early this morning
due to frontal boundary. Current water vapor imagery/RAP
analysis show a surface low situated over the spine of the
Keweenaw with its occluded frontal boundary extending
northeastward into Ontario and arcing southwestward into
Minnesota. As that boundary pushes northward as a warm front
this morning, any remaining showers and thunderstorms will exit
Upper Michigan to the north after Tue 12Z. And, this will
result in a short break from the active weather before another
round by this evening and a mostly sunny day. The downside,
though, will be the hot temperatures as the UP resides in the
warm sector along with strong southerly surface winds under
ample mixing. Temperatures will soar to near the 90 degree mark,
combined with dew points in the 70s, pushing heat index values
into the mid 90s. And, southerly winds will be sustained at 10
to 20 mph, gusting to 30 mph, especially across downslope areas
near Lake Superior.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
Issued at 407 AM EDT Tue Jun 18 2024

The overall consensus of both ensemble and deterministic guidance
packages suggests the pattern across CONUS will continue to include
a stout mid-upper level ridge over the eastern third of CONUS while
deep and broad troughing holds fast over the western third. This
places Upper Michigan in a predominate south to southwest flow
regime and open to both Gulf of Mexico moisture and a warm/hot
airmass, and on the path for any shortwave, impulse, or MCS
developing across the Plains, at least until the weekend when a more
zonal pattern begins to emerge.


The low currently ejecting out of the central Plains early this
morning will move into Ontario tonight, slowly dragging a cold front
through Upper Michigan tonight through Wednesday. Showers and
thunderstorms begin to move into the western UP as early as this
evening, which will present another opportunity for some strong to
severe storms given impressive CAPE and sufficient shear over the
area. However, this risk remains limited and wanes further eastward
as given an unfavorable timing of the frontal passage. Will note
that most of the hi-res guidance indicates that convection will be
able to make it even as far eastward as M-95 overnight. However,
where storms can develop, heavy rain will yet again be a concern
with near 2in PWATs. As the front continues to slowly track through
during the day Wednesday, expect additional convection to develop
along it with weak daytime instability. Otherwise, expect
temperatures to come in cooler than Tuesday, with highs ranging in
the 70s behind the front and the upper 70s to lower 80s ahead of it.
Dewpoints in the 60s ahead of the front will keep things feeling
rather muggy.

The front largely clears the area Wednesday evening, with PoPs
receding southward as high pressure builds in. Thursday looks to be
mostly dry as the pattern begins to shift into something more zonal,
but some showers cannot be totally ruled out with weak impulses
rippling through. As another shortwave begins to eject out of the
Rockies, another warm front will lift into the Upper Great Lakes
Thursday night/Friday, potentially supporting showers/storms
Thursday night into early Friday. The boundary appears to stall out
Friday over the Upper Great Lakes as a surface low deepens and lifts
out of the Central Plains. The low will press through the region
Saturday night and Sunday while the shortwave aloft takes on a
negative tilt. For a few days now, guidance has been suggesting this
setup, which could lead to a potential heavy rain/flooding event in
some areas in Upper Michigan as PWATs again increase to as high as
200% of normal. Of course, this will be dependent on preceding rain,
but this system warrants monitoring.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 137 AM EDT Tue Jun 18 2024

With a warm front lifting n across the area overnight, sct shra/tsra
will continue. A developing downslope se wind at IWD overnight
should keep conditions VFR, but if a shra/tsra does pass across the
terminal, brief MVFR/IFR could occur. At CMX, upslope ese winds
should result in MVFR/IFR overnight while at SAW, developing upslope
sse winds should maintain LIFR. LLWS is expected into the morning at
IWD/CMX. CMX/SAW will break out to VFR early this morning, and all
terminals will see gusty southerly winds to 25-30kt today. Gusts to
35kt possible at IWD. Approaching cold front should bring shra/tsra
into western Upper MI toward late evening.

&&

.MARINE...
Issued at 407 AM EDT Tue Jun 18 2024

A warm front lifting northward early this morning is supporting
additional showers and some thunder, but showers largely move north
of the area shortly after sunrise. Meanwhile, light winds to start
us off will keep in a potential for some patchy dense fog through
the morning.

South of the warm front, a strong low level jet will move over Lake
Superior ahead of a cold front moving eastward through Minnesota.
This low level jet will support southerly winds upwards of 30kts
across eastern Lake Superior, possibly some low end gales for higher
reporting platforms or where topography plays a local influence on
winds near the lakeshores between Marquette and Whitefish Pt. Cold
front will press through the lake tonight through Wednesday,
potentially supporting another round of strong to severe storms
across western Lake Superior and thunderstorms and showers lake-
wide. Winds slowly fall back below 20 knots while turning mainly to
the west behind the front Wednesday afternoon. High pressure appears
to try to work in Thursday but will be dependent on upstream
systems. Another front moves over the lake Friday/Saturday as a low
pressure approaches from the west, bringing with it another round of
showers/storms. Current thinking is for light winds in this system
outside of thunderstorms.

&&

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

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...TDUD
LONG TERM...LC
AVIATION...Rolfson
MARINE...LC