660
FXUS63 KMQT 031853
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
253 PM EDT Thu Jul 3 2025

.KEY MESSAGES...

- Hot and humid conditions return Friday and Saturday. Please practice
  necessary heat safety measures if you plan on participating
  in outdoor holiday weekend festivities.

- A warm front may bring scattered showers and storms Friday
  morning and afternoon across the western half of Upper
  Michigan.

- Showers and thunderstorms are expected Saturday afternoon into
  Sunday morning. Heavy downpours and lightning should be
  expected in these storms. Some storms could be strong to
  severe Saturday afternoon and evening.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 252 PM EDT Thu Jul 3 2025

High pressure over the area has supported mostly clear skies and
light winds, allowing the forecast area to warm into the 70s away
from Lake Superior. Lakeside, temps have only warmed into the 60s.
Effective mixing has allowed RH values to fall into the 30 and 40
percents, but a couple isolated high 20s have been observed.

Tonight, high pressure will wane as the next system builds into the
region. Warm front associated with this system will approach,
resulting in increasing cloudiness and a mild overnight period for
the west. There overnight lows may only cool into into the upper 50s
to mid 60s. Elsewhere, overnight lows in the low to mid 50s are
expected.

The warm front will lift through the region Friday morning, with
associated convection ahead of the boundary diminishing through the
morning and afternoon. From there, we look to warm into the mid to
upper 80s, perhaps breaking 90F in the downslope prone areas of
Ontonagon and southern Houghton counties. Given the dewpoints
climbing into the upper 60s to low 70s, heat index values climb into
the 90s, potentially mid to upper 90s. The western U.P. is in the
Orange and Red category (or 2 and 3 of 4 category) for being at risk
of heat related impacts. Those planning to be outside Friday should
plan on limiting their time outside, especially if they are prone to
heat related illness or are without adaquete cooling systems. The
east should be cooler, peaking in the low 80s away from the lake,
given overlake flow moderating the airmass a little. Warm and humid
conditions continue Friday evening and night, with widespread near
mid to upper 60s to near 70 degree lows expected across the forecast
area.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 252 PM EDT Thu Jul 3 2025

Beginning Saturday, mid-upper level ridge axis will be just
downstream with a shortwave pressing into the west. This shortwave
looks to support a surface low developing along a cold front as it
presses west to east through the forecast area into Sunday. Near
zonal flow stretching across the Northern Tier Sunday and Monday
will be interrupted by a couple weak shortwaves. The first will move
through Upper Michigan Sunday night/Monday and the second follows
Monday night while high pressure at the surface keeps the region
mostly dry. The third wave, potentially Tuesday/Tuesday night, may
overlap with a slowly moving frontal boundary, which may support
precipitation. Another wave may dip down into the region Wednesday
in the lee of upper level ridging across the Northern Plains and
central Canada. Overall, this provides for showers and thunderstorms
Saturday, notably with a Marginal risk for severe weather Saturday.
Humid with warm to hot temperatures look possible on Saturday, but
afterwards the pattern favors mostly widespread 70s for daytime
highs and 50s interior/ near 60 for overnight lows.

A deeper look at Saturday into Sunday...overall good consensus of
the day beginning dry under southwest flow with the surface cold
front upstream in Minnesota. Southwest flow with a 30-40kt 925-850mb
LLJ ahead of the boundary will support breezy winds, potentially
producing a moderate to high swim risk for Lake Michigan beaches of
Schoolcraft County by afternoon. The moist flow will enable
increasing instability, potentially 1500-2500 j/kg MUCAPE, through
the day thanks to the forecast area heating up into the 80s to near
90F with dewpoints near 70F. By afternoon, showers and thunderstorms
are expected to develop in this environment ahead of the eastward
moving cold front, potentially supporting strong to severe
thunderstorms. If this occurs, strong to damaging winds, frequent
lightning, and heavy downpours will be the main risks. Deep warm
layer, PWATs climbing climbing to near 2 inches, and Corfidi vectors
of 5-15 kts suggests training storm potential and heavy rain/flash
flooding risk. Right now WPC suggests only a marginal risk of flash
flooding (at least 5%), but will be something to monitor. Those with
outdoor plans Saturday afternoon and evening should stay weather
aware just in case precipitation or severe weather impacts their
plans. The system slowly inches through the region overnight, with
lingering precip across the east half Sunday morning.

Afterwards, surface high over the area looks to keep the region
mostly dry through Tuesday despite a few different upper level waves
moving through. Tuesday, a wave diving southeast in the lee of mid-
upper level ridge atop a slow moving surface boundary may be enough
to support the next round of precipitation.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 120 PM EDT Thu Jul 3 2025

VFR conditions and light winds are expected today and tonight. Some
elevated haze will be possible thanks to upstream Canadian wildfires
billowing in smoke into the region. Otherwise, warm front lifting
into the area late tonight into Friday may result in showers/storms
at KIWD and increasing sky coverage elsewhere.

&&

.MARINE...
Issued at 252 PM EDT Thu Jul 3 2025

NE winds increase to 15-20 kts across the western arm of the lake
this afternoon while remaining lighter and out of the southeast
across the rest of the lake. Tonight, expect winds to slacken in the
western arm of the lake while increasing to 15-20 kts across the E
half into the early hours of Friday. Winds turn mainly to the SSW
Saturday, and remain elevated at around 15-20kts across most of the
lake before falling back below 20kts and turning to the NW Sunday.
Winds remain light into early next week. Waves increase to around 2-
4ft especially across the eastern half of the lake Friday, then fall
back to around 1-3ft this weekend (highest east half).

&&

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

&&

$$

SHORT TERM...JTP
LONG TERM...JTP
AVIATION...JTP
MARINE...LC