616
FXUS63 KMQT 120854
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
454 AM EDT Fri Jul 12 2024

.KEY MESSAGES...

- ~20% chance of isolated diurnally driven showers/thunderstorms
this afternoon.

- Hot and muggy conditions this weekend with the potential for a few
strong to severe thunderstorms Saturday through Monday.

- Cooling and drying trend into the midweek portion of next week
with the arrival of high pressure.

&&

.SHORT TERM /TODAY/...
Issued at 452 AM EDT Fri Jul 12 2024

Under clear skies and calm winds early this morning, dewpoint
depressions have been lowering.  As a result, will carry a patchy
fog mention across central and eastern portions of Upper Michigan
through Fri 12Z.  Any fog that does form, however, will quickly burn
off by mid-morning.  Focus then turns to the high temperatures and
potential for diurnal convection later today. Height rises
through the day should help to mitigate any widespread
convective activity. But, some of the CAMs continue to hint at
slight chances (~20%) for isolated showers/thunderstorms this
afternoon as SBCAPE values reach the 500-1200 J/kg range with
daytime highs topping off in the mid to upper 80s. As a result,
could not trend toward a completely dry forecast and inserted
mention of 20% chance Pops across much of the interior west and
central as well as portions of the east where HRRR is
pinpointing some isolated higher SBCAPE values.

&&

.LONG TERM /TONIGHT THROUGH THURSDAY/...
Issued at 328 AM EDT Fri Jul 12 2024

A more active period starts out the extended period as a shortwave
moves over the area this weekend before a Clipper low brings more
precip to the U.P. early next week; some very warm temperatures are
expected Saturday and Sunday, and severe weather could be seen
Sunday and Monday. Once we get behind the Clipper low though, expect
high pressure ridging to finish out the rest of next week as a
developing rex block develops eastwards into the Central U.S.

The last of the afternoon convection ends early this evening as the
sun sets and we lose the diurnal heating. With upper level ridging
moving overhead and sfc level ridging holding on over our area
tonight, expect mostly clear skies with low temperatures getting
down to around 60 in the interior areas. Moving into Saturday, a
shortwave trough looks to move into our area from the west. However,
it will still have to fight against localized high pressure over the
Upper Great Lakes throughout the day, which may limit the cloud
cover and convection to only a few hours in the afternoon over the
east and possibly late in the afternoon over the west. With weak
warm air advection occurring throughout the day and southerly winds
too, expect very warm conditions Saturday, with highs getting into
the 80s across most of the area; some spots could get to or exceed
90, particularly the downslopes near Lake Superior (ex. L`Anse).
Moving into the Saturday night, the chances for scattered showers
and thunderstorms increases as the shortwave begins moving through
the U.P.; while there looks to be enough instability to continue the
convection through Saturday night, the available CAMs do show
convective activity decreasing during the overnight hours. Shower
and thunderstorm chances continue through Sunday as a secondary
shortwave from the Northern Plains reinvigorates convection across
the area. With bulk shear increasing to around 30 knots or more, and
with model guidance uniformly showing MUCAPEs of 1000 J/kg or more
over the area, some strong to severe thunderstorms could be seen.
Looking at model soundings, it appears that the primary threat will
be hail, with a secondary threat of severe winds as the convective
instability is present above a thick layer of CIN in the lower
levels. Another very warm day is in store for us Sunday, with highs
pretty similar to Saturday as generally weak southwest surface flow
dominates the U.P.

A Clipper low brings additional showers and thunderstorms to our
area early next week, although there is some model divergence as to
when the convection associated with the low arrives; it could arrive
as early as late Sunday night or as late as Monday afternoon.
Regardless, more severe weather could be seen as bulk shear values
increase in comparison to Sunday. However, CAPE values do not look
to be as high. Therefore, with the better CAPE being in the interior
areas Monday, any severe weather we do see will likely be relegated
to this part of the U.P.; the primary threats will be severe hail
and winds Monday.

Besides maybe some light afternoon showers Tuesday, expect a drier
and less active weather pattern for the last half of the extended
period as high pressure builds in from the west. Behind the Clipper
low, we could see temperatures drop to well below normal; the ECMWF
EFI shows max temperatures in the -0.5 to -0.7 range Wednesday,
meaning we could see highs only get into the 60s across some
portions of the U.P. on that day. However, as we head towards the
end of next week, expect the temperatures to gradually return to
near normal as the surface ridging continues eastwards and allows
warmer air to advect into our area.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 113 AM EDT Fri Jul 12 2024

VFR conditions will prevail during this period. Expect light winds
with mostly clear skies tonight. By afternoon Friday, diurnal
cumulus may develop, but VFR conditions should continue.

&&

.MARINE...
Issued at 328 AM EDT Fri Jul 12 2024

Light winds of 20 knots or less are expected to continue today
through this weekend until early next week as zonal flow aloft
continues overhead for the next couple of days. That being said, a
couple of shortwave lows may bring some scattered showers and
thunderstorms over the lake late Saturday through Sunday; some of
the thunderstorms could be strong to severe on Sunday. A Clipper low
looks to bring additional showers and thunderstorms to the lake
Monday into Monday night; some strong to severe storms could be
seen, especially along the southerly nearshores with this Clipper.
Behind the Clipper`s cold front, we could see northwesterly to west
winds getting up to 20+ knots Monday night and Tuesday.

Some patchy dense fog could be seen in the wake of each round of
precipitation over the next several days.

&&

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

&&

$$

SHORT TERM...TDUD
LONG TERM...TAP
AVIATION...JTP
MARINE...TAP