962
FXUS63 KMQT 190504
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
104 AM EDT Wed Aug 19 2026

.KEY MESSAGES...

- Temperatures will be close to seasonal averages most days
  through the week, with highs in the 70s and lows in the 40s
  and 50s.

- Showers and thunderstorms are possible (40-70% chance) late
  Thursday into Friday as a weak system moves through the area.

&&

.DISCUSSION...
Issued at 249 PM EDT Tue Aug 18 2026

The general pattern through the forecast period and toward the end
of August places the UP under northwest flow aloft. This yields
seasonal to slightly cooler than normal temps, captured by the CPC 6-
10 day temp outlook. The mid level closed low over northern Ontario
and Hudson Bay gradually makes its way to northern Quebec for
Thursday into the weekend, but likely will be replaced by another
deep trough early next week. Model discrepancies exist regarding the
timing and placement of this trough (or if another closed low
develops), but this currently does not yield significant changes to
the northwest flow anticipated for over the Upper Great Lakes.

Afternoon observations have placed the cold front now over central
and eastern Upper MI with temps in the 70s to low 80s ahead of it.
Tds in the upper 50s to low 60s and PWATs struggling to reach 1.2
inches are not terribly impressive, but steep low level lapse rates
and SBCAPE values up to 1500 J/kg are present over parts of the east
half. Strong bulk shear is present up to 50 kts on the latest SPC
mesoanalysis page. As low level f-gen increases with colder 925 mb
temps pressing south from eastern Lake Superior, isolated convection
continues. These could bring gusty winds and small hail, but severe
weather is not expected until outside the CWA.

A much drier airmass moves in tonight behind the cold front. Mostly
clear skies and light winds support (between 5-10F) colder than
normal temps. Lows are expected in the 40s to mid 50s, coldest
interior west where upper 30s are anticipated. High pressure builds
in over the Great Lakes through Wednesday, keeping dry and
comfortable conditions going. The blended guidance mean has been
running several degrees too warm during recent cool nights, thus
have opted for the lower end of the distribution, 10th percentile
for low temps tonight and tomorrow night. Highs in the 70s on
Wednesday will once again be followed by lows in the 40s to mid 50s,
coldest interior west where temps dip into the mid to upper 30s.

High pressure over the Great Lakes Thursday morning shifts
southeast, giving way to a shortwave and weak sfc trough the west.
WAA reintroduces rain chances into Thursday night and a trailing
shortwave continues PoPs on Friday. Strong to severe storms are not
expected given that probabilities of 1000 or greater CAPE values
struggle to reach 30% until Friday when bulk shear falls off. As far
as rainfall amounts go, 24 HR NBM probabilities for 0.25 inches or
more are in the 30-60% range with 15-25% chances for at least 0.75
inches. While any storms that do form could put down locally heavy
rainfall, a widespread heavy rainfall is not expected. Thus not
expecting appreciable improvements to the ongoing drought conditions
over the south and west. A cold front on Saturday yields one more
day of showers and non severe storm chances (15-30%) before high
pressure returns with mostly dry weather into early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 103 AM EDT Wed Aug 19 2026

VFR conditions continue today as high pressure ridging pushes
through the region. Expect the winds to become lake breeze dominated
by the afternoon hours.

&&

.MARINE...
Issued at 321 PM EDT Tue Aug 18 2026

Lake Superior - Southwest winds of 15-25 kts are expected over the
west, particularly between Isle Royale and the northwest shores
where winds are funneled. Winds shift northwest tonight as they fall
below 20 kts lakewide. High pressure building in through Thursday
morning keeps winds below 20 kts through Friday. A cold front on
Saturday increases northwest winds to 15-20 kts lakewide,
particularly over the east where gusts approach the 25-30 kt range.
Northerly winds remain elevated until Sunday night when high
pressure brings back calmer conditions. A few thunderstorms are
possible in the west Thursday evening, but strong to severe storms
are not expected.

Northern Bay of Green Bay and northern Lake Michigan - Overall
expect winds less than 20 kts through Thursday night. Scattered
showers and storms are expected into this evening as a cold front
pushes through the area. These could bring marginally severe wind
gusts up to 35 kts and small hail. A system Thursday night and
Friday brings back shower and storm chances, but strong to severe
weather is not expected. Southwest wind gusts up to 25 kts are
expected ahead of this system on Friday, particularly near
Manistique. Winds diminish Friday night, then become northwest for
Saturday, once again increasing gusts up to 20-25 kts for the
weekend.

&&

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

&&

$$

DISCUSSION...77
AVIATION...TAP
MARINE...77