677
FXUS63 KMQT 070713
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
313 AM EDT Sun Jul 7 2024

.KEY MESSAGES...

-Scattered showers and thunderstorms over mainly the west half
 of Upper MI this afternoon.

-Through at least Tuesday, daily chances of showers and
 thunderstorms, highest chances in the afternoons.

-Drier weather expected for the last half of this week. Could
 see highs reach into the 90s by Friday/Saturday.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 258 AM EDT Sun Jul 7 2024

Water vapor imagery and RAP analysis show mid-level troffing over
central N America. Within the trof, a well-defined shortwave is over
western MN with additional shortwaves dropping se from the Canadian
Prairies thru eastern MT/western Dakotas. In association with the MN
shortwave, shra and some tsra extend from nw MN se thru eastern MN
into IA. Closer to home, it`s been a quiet overnight under clear to
partly cloudy skies and little to no wind. A few of the traditional
interior cold spots are down to 50, but current temps mostly range
from the mid 50s to lwr 60s F.

Aforementioned shortwave over western MN will drift ne today and
will be over ne MN/western Lake Superior by sunset. On this track,
best forcing will shift over western Upper MI this aftn. Models
indicate roughly 300-1000j/kg of MLCAPE will build today. Of the 00z
models, the HRRR is around and blo the low end of that range. On the
opposite end of the spectrum is the NAM which is often on the high
side. It shows widespread 1000-1500j/kg building today. With deep
layer shear on the order of 25-35kt, expect some storm organization,
and if the NAM`s greater instability materializes, there would be a
risk of an isold svr storm. Instability build up will be something
to monitor during the morning into the aftn, but with expectation of
lower instability per bulk of guidance, don`t currently anticipate
any svr storms to develop this aftn. Some brief gusty winds/small
hail is a possibility in addition to the brief hvy downpours that
will accompany some of the storms. While some of the shra to the w
and sw may brush the Ironwood vcnty mid morning, expect shra/tsra to
begin to develop toward noon or early aftn and then quickly expand
across roughly the w half of Upper MI, greatest coverage generally w
of a L`anse to Iron River line. Lake breeze will try to develop and
shift inland from Lake Superior into Alger/Luce counties. Should end
up pinned along or very close to shore. The resulting convergence
combined with building instability on the land advecting northward
across the boundary on lower level southerly winds brings the
potential of isold shra/tsra development e of Marquette toward
Whitefish Pt (including the nearshore waters of Pictured Rocks
National Lakeshore) as well during the aftn. These isold shra/tsra
may end up mostly offshore unless the lake breeze can make a bit of
inland progress. Expect high temps today to be mostly in the mid 70s
to lwr 80s F.

&&

.LONG TERM /TONIGHT THROUGH SATURDAY/...
Issued at 311 AM EDT Sun Jul 7 2024

While we`ve seen a very progressive pattern thus far this summer, a
blockier pattern is now being realized as a large 500mb high
pressure ridge over the western U.S. slowly drifts eastwards into
the central and eastern U.S. this week. While this will allow weak
shortwaves to rotate over us during the first half of this week, the
blocky pattern will bring high pressure ridging to finish out the
last half of this week, probably (70% chance) bringing drier weather
with it, possibly the driest weather we`ve seen since the start of
summer. Additional details for the extended forecast follow below.

The scattered rain showers and thunderstorms over the western U.P.
this evening dwindle as the CAPE produced by the sunshine earlier in
the day dies down with the setting sun and as the remaining
convective cells utilize what`s left of the energy in the
atmosphere. While no severe weather is expected, there is just
enough instability and shear in the early evening hours to maybe
squeak out some sub-severe winds and small hail in some of the
stronger storms, in addition to lightning and heavy rainfall. Behind
the convection over the west half, we could see some patchy fog
develop around midnight tonight and stay until a couple of hours
after dawn Monday morning. As the shortwave behind the convection
today continues northeastward, a few isolated light rain showers and
maybe a stray thunderstorm or two looks to develop over the central
U.P. tonight before a secondary shortwave low from the Central
Plains lifts into the area and redevelops scattered rain shower and
thunderstorm activity over the eastern U.P. late tonight/early
Monday morning. As we move into the daylight hours Monday, CAMs have
convection redeveloping over the rest of the U.P. by the early
afternoon too. While there won`t be as much CAPE to work with during
the day Monday given the cloudier skies, with the secondary
shortwave being slightly stronger, expect to see a similar day to
what we will see today, with a couple of stronger storms possibly
producing sub-severe hail and winds. As the secondary shortwave
continues northeastward into Canada, expect the convection to
dwindle after sunset and to become relegated mainly to the east. A
tertiary shortwave moves through on Tuesday and brings more light
rain showers and thunderstorms over the inland areas by the
afternoon hours due to convection being highly dependent on the
instability caused by diurnal heating (weak forcing from the
shortwave low). The last of the showers and thunderstorms looks to
die out over the interior west Tuesday evening.

Moving into the latter half of this week, model and ensemble
guidance shows sfc ridging building over northern Ontario as the
high pressure block currently over the western U.S. slowly shifts
eastward. This high pressure ridge could very well keep us dry
through the rest of this week as early as Wednesday onwards. That
being said, there is a chance (~30%) that yet another weak shortwave
will bring light rain showers and thunderstorms back over the
interior areas Wednesday before we remain dry for the rest of the
week. Also worth noting is that the remnants of now Tropical Storm
Beryl have trended further north over the past 24 hours as it
traverses the interior U.S.. While the chance of seeing rainfall
from Beryl`s remnants is slim (<20%) given that the model and
ensemble consensus brings the track through Detroit, we could see
some light showers and maybe a thunderstorm or two over the eastern
U.P. come Wednesday/Thursday should the model guidance continue the
northward trend in Beryl`s track (see the 00z run of the GFS for an
example). Otherwise, the only other thing worth noting is the
gradually increasing temperatures throughout the last half of this
week into early this upcoming weekend; we could see high
temperatures reach into the 90s by Friday/Saturday.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 123 AM EDT Sun Jul 7 2024

VFR conditions will prevail at all TAF sites through the period.
Calm conditions are expected for the rest of the night before a weak
surface low moves into northern Minnesota today. This wave, along
with diurnal instability, should result in scattered showers and
thunderstorms developing around IWD in the early to mid-afternoon,
where a PROB30 was placed during the window when tsra are most
likely. Lower probability of tsra making it to CMX/SAW in the late
afternoon and evening, so it was not included in the TAFs.

&&

.MARINE...
Issued at 311 AM EDT Sun Jul 7 2024

Light winds of generally 20 knots or less continue through this week
as high pressure ridging over the western U.S. slowly drifts
eastwards throughout the forecast period. That being said, some
thunderstorms are possible across the lake this afternoon through
tonight, and then along the nearshores Monday and Tuesday; while no
severe weather is expected, some notably stronger winds and small
hail could be seen in some of the stronger storms today and Monday.

&&

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

&&

$$

SHORT TERM...Rolfson
LONG TERM...TAP
AVIATION...Thompson
MARINE...TAP