721
FXUS63 KMQT 031841
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
241 PM EDT Sun Aug 3 2025

.KEY MESSAGES...

- Mostly dry and warm weather persists into the first half of
  the work week.

- Afternoon lake breeze development may kick off a few showers
  in the central and eastern U.P. Monday.

- Smoke from Canadian wildfires will continue impacting air
  quality and may locally reduce visibility at times. An Air
  Quality Alert remains in effect for all of Upper Michigan.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 152 PM EDT Sun Aug 3 2025

Early afternoon RAP analysis and GOES satellite imagery reveal clear
skies underneath an upper ridge and sfc high pressure placed
overhead the Ohio River Valley and Great Lakes region. Upstream, a
weak, slow moving trough extends back towards the far northern
Plains and western Minnesota. Closer to home, temps have warned into
the 70s across the UP, and should continue to rise towards 80
through the afternoon. Breezy westerlies will give way to lake
breeze development this afternoon, eventually becoming calm and
variable tonight. Look for low temps in the 50s interior closer to
60 near the lake shores.

Heading into Monday, the UP will be situated on the backside of the
sfc high thats meandered into the eastern seaboard. The
aforementioned upstream shortwave slowly moves into western WI,
tossing some loosely organized vorticity into the western UP which
will help to increase cloud cover. Some global models want to kick
off a few showers in the west, but confidence is low enough to leave
out of the forecast. With light southerly flow and sfc high pressure
influencing the area, CAMs suggest afternoon lake breeze development
will take place. Some CAMs do suggest some convection firing along
the lake breeze, especially in the central and eastern UP, though
model soundings show quite dry low levels that may prevent
convective initiation or hinder any developing precip from reaching
the ground. Opting to draw in some low chance (<25%) PoPs along the
typical central/east UP lake breeze locations for the afternoon to
account for this scenario. If convection does fire, nothing more
than showers and maybe a rumble of thunder is expected given weak
shear and CAPE values nothing to write home about.

Additionally, with generally light winds through much of the
atmospheric column, smoke and haze from Canadian wildfires will
continue to linger across the Great Lakes. Thus, the Michigan EGLE
has opted to extended the ongoing AQA through Monday. See the latest
AQA extension for more details and air quality information.

Monday night lows fall back a bit warmer than previous nights
towards the mid to upper 50s interior and low 60s lake shores,
starting off a warming trend as we head into the rest of the week
and extended forecast period.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 240 PM EDT Sun Aug 3 2025

Moving further into the work week, a rather complex setup emerges
that the ensembles and global deterministics are struggling to
define. The key elements at 500mb are a ridge moving over the
Canadian Prairie, a trough over the Mississippi River valley, semi-
permanent highs over the southwest US and Bermuda, and deep troughs
over British Columbia and Atlantic Canada. While all of these
features are large and slow-moving, their complex interactions are
handled differently depending on model of choice. Blending most
solutions together, the NBM, previously advertising low chance PoPs
Wednesday afternoon, now keeps the UP dry until Thursday and into
the following weekend with low chance (15-30%) PoPs hovering over
the central and western third. This reflects high certainty that the
pattern will break down to some degree but a low certainty in how it
will break down. Early indications are that the Canadian ridge will
go omega-shaped, and the western trough may pivot into the Upper
Great Lakes for the latter part of the work week.

Into next weekend, the pattern breakdown becomes chaotic, so further
shortwaves are possible but determining which one is the most likely
solution is difficult. With persistent diurnal heating and height
rises, and prevailing flow at mid to lower levels having a more
southerly component, temperatures will trend above normal with the
latest NBM showing widespread 30-60% chances of 90 degree highs by
Friday, and up to 90% chances for the downsloping Lake Superior
shores by Wed-Thurs. This in conjunction with a moistening trend in
dew points thanks to reestablished connection with Gulf or Corn Belt
moisture will increase instability through the week with mean LREF
SBCAPE values of over 1500 J/kg for the interior west by 00Z
Thursday, and 2000 J/kg Friday/Saturday. As a result, if given
forcing, thunderstorms will be back in the conversation for the
latter half of next week.

Additionally, while upcoming warming trend and temps pushing or
exceeding 90 degrees may be manageable for some, the combination of
above normal temperatures and increased humidity will put those
without efficient cooling at risk for heat related impacts. Current
NWS HeatRisk Tool suggests Moderate (level 2 of 4) to Major (3 of 4)
impacts by next weekend across the northern tier and western UP.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 152 PM EDT Sun Aug 3 2025

VFR conditions prevail at all TAF sites through the 18z TAF period
as sfc high pressure slides across the Lower Great Lakes. Under
primarily light westerly flow, lake breeze development is beginning
to occur off of Lake Superior and should cross SAW ~20-21z, veering
winds to the N-NW. Breezy winds 10-15 kts will quiet down tonight.
Tomorrow, lake breeze action may kick off a few showers and maybe a
thunderstorm in the central and eastern UP, but confidence is low
(<25%). Lingering wildfire smoke may impact visibility aloft, but is
not expected to lower sfc vsby below 5-6sm.

&&

.MARINE...
Issued at 240 PM EDT Sun Aug 3 2025

Under primarily high pressure, winds will remain below 20 kt for
most of this forecast period. Otherwise, expect wildfire smoke to
cause poor air quality at least through Sunday. There will be some
chances of thunder next week, though model guidance is widely spread
in the timing and location details at this time.

&&

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

&&

$$

SHORT TERM...BW
LONG TERM...BW
AVIATION...BW
MARINE...BW