493
FXUS63 KMQT 150541
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
141 AM EDT Sat Jun 15 2024

.KEY MESSAGES...

- Dry through Saturday before the return of showers and
  thunderstorms later in the weekend.

- Warmer than normal next week with frequent chances for showers
  and storms.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 203 PM EDT Fri Jun 14 2024

GOES-16 visible imagery shows a fair-weather cu field away from Lake
Superior across the UP, but otherwise clear skies are over the UP
today. RAP analysis shows ridging over the Plains advancing towards
the Upper Great Lakes, which the negative vorticity advection is
supporting a near-1020mb high pressure over Lake Superior this
afternoon. With the high pressure expected to linger over the region
through at least Saturday morning, no precipitation is expected.
While the main component of the wind is northerly, flow is weak
enough that local influences and lake breezes are allowing for light
and variable winds in some spots through this evening. Overnight, as
the high shifts slightly, winds will gradually become more
southerly, though should remain below 10 kt. Clear skies over the
east will allow temperatures to fall to the low 40s per bias-
corrected gridded MOS guidance, with some scattered skies over the
west half keeping lows around 50.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 452 PM EDT Fri Jun 14 2024

The pattern becomes increasingly amplified heading into next week as
a mid-level trough digging into western North America amplifies a
ridge from the Great Lakes through the Atlantic Coast into eastern
Canada. This pattern transition will result in much warmer,
summerlike weather for Upper Mi by next week. A series of shortwaves
riding over the ridge will also bring episodes of showers and t-
storms heading into next week with the next best chance likely
occurring Sat night into Sunday.

Dry weather continues for most of Saturday with the midlevel ridge
axis sliding over the area supporting surface high pressure centered
over eastern Ontario and the Lower Great Lakes. As a weak shortwave
emerges out of the Central Plains, the pressure gradient tightens
over the area resulting in increasing southerly winds for the
afternoon with gusts to 20 mph possible for much of the UP. Cloud
cover will also be on the increase throughout the day ahead of the
approaching wave.

Ahead of a more prominent shortwave advancing from the Plains, sfc-
850 mb theta-e advection will strengthen on the nose of a developing
50-60kt LLJ as chances for showers and thunderstorms sneak into the
western UP by early evening. PoPs will increase as showers/t-storms
spread east across the forecast area Sat night into Sun morning.
Although the timing of the shortwave`s arrival will be less
favorable for strong/severe surface-based convection as soundings
initially show weak elevated instability, the impressive
lift/dynamics (0-6 km shear of 40-50 kts or higher) could still be
supportive of stronger storms with gusty winds and small hail
especially as one gets into the daytime hours on Sunday as
instability increases. This wind/hail threat has been recognized by
SPC issuing a Marginal Risk for Day 3 (Sunday). Heavy rain will be a
threat as well with the stronger t-storms, as PWATs increase to
generally 1.5-2 inches. Temperatures fcst in the 70s on Saturday
should increase on Sunday, especially west half where there could be
partially clearing in the wake of the passing shortwave. Readings
over the west half should increase into the lower to mid 80s in the
afternoon and this heat combined with dew points in the 60s will
result in muggy and increasingly uncomfortable conditions.

Warm and unsettled weather will continue into next week. Monday
through midweek, the Great Lakes will be situated between high-
amplitude ridging over the Eastern Seaboard and deep troughing over
the Rockies. Persistent southerly flow into the area will continue
to pump in a warm, moist airmass; look for highs Monday and Tuesday
to range well into the 80s for most of the area and even a few low
90s readings possible over the interior west half and in the
typically warmer southerly downsloping spots. With dewpoints well
into the 60s, it will get uncomfortably muggy. Given this unstable
airmass and our area situated on the perimeter of the ridge, passing
weak waves will leave us with chances for showers and storms both
Monday and Tuesday, although mid-level capping from the dome of heat
over the area could at the same time keep a lid on some of the
convection. With deep layer shear still at 40-50 knots on Monday,
any convection that pops that day could have a shot of going severe.
Southerly winds will noticeably increase and become gustier on
Tuesday as a midlevel shortwave ripples out of the Rockies with a
surface low likewise closing off and heading into the Northern
Plains, leading to a tightening pressure gradient over the area.
Another strengthening LLJ of 40-50 kts may provide the lift needed
for some additional convection Tuesday night into Wednesday while
the surface low moves through Ontario and sends a frontal boundary
across the area. From midweek onward, temperatures will trend more
towards normal while the heat dome pattern governing the early part
of the week breaks down, although more episodes of convection are
possible Wed-Thu as more shortwaves ride along the frontal boundary
lingering just to our south.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 140 AM EDT Sat Jun 15 2024

VFR conditions continue the rest of this morning through the late
afternoon. However, as a low pressure approaches from the west
today, expect clouds to continue to fill-in and for cigs to slowly
lower from west to east throughout the day. Some calm to light
southerly winds early this morning pick up a from the south after
dawn into the afternoon hours. Some of the first rain showers could
be seen over KIWD by the end of the TAF period, with KIWD and KCMX
possibly dipping into MVFR conditions by 06z tomorrow.

We could (50% chance) see some marginal LLWS near KCMX early this
morning, but given that it`s so marginal and it`s near dawn (when
mixing and gustier winds could make it to the sfc), I`m not going to
include it in the TAF at this time. We could also see some marginal
LLWS at all the TAF sites come tonight, but the chances are again
still rather low (30%).

&&

.MARINE...
Issued at 452 PM EDT Fri Jun 14 2024

High pressure ridging over the Great Lakes will lead to tranquil
conditions into Saturday. Winds mainly out of the SE Saturday will
be on the increase by the late afternoon, gusting up to 20 knots in
the eastern half of the lake. Wind gusts to 20-25kts will be
possible Sunday, then winds fall back below 20 kts Monday before
increasing out of the SSE again Tuesday with maybe some gusts to 25
knots over the eastern lake. Waves should generally be below 3ft for
most of the period, but are expected to increase to around 3-5ft
across the eastern half of the lake Sunday.

&&

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

&&

$$

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