651
FXUS63 KDLH 222336
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
636 PM CDT Fri Aug 22 2025

.KEY MESSAGES...

- Showers/storms over northwest WI depart to the east by early
  evening.

- A secondary cool front will keep a small chance of isolated
  storms in the forecast this evening over north-central
  Minnesota.

- Cooler, fall-like temperatures are expected this weekend into
  early next week with highs in the 50s and 60s through Monday.

- Patchy frost is possible, especially Tuesday morning, for
  inland locations away from Lake Superior.

&&

.DISCUSSION...
Issued at 331 PM CDT Fri Aug 22 2025

A cool front over northwest Wisconsin supported an area of
thunderstorms early this afternoon. The front and convection
will depart to the east by early evening. Meanwhile farther
northwest, a secondary cool front from northwest Ontario through
northwest Minnesota to eastern North Dakota will propagate
southeastward across the Northland tonight and Saturday morning.
Ahead of that front abundant sunshine and moisture pooling will
produce potential instability of 500-1000 J/kg of MLCAPE by
late afternoon. A narrow broken line of showers and an isolated
storm or two developed over the past hour over northwest
Minnesota. Look for a slight chance of showers/storms to persist
into early evening over north-central Minnesota as that
secondary front moves in.

Cold air advection aloft behind the cool front will advance
into the region tonight with an increase in cloud cover
expected. Think the clouds will be sufficient to prevent
widespread dense fog. Patchy fog is possible in low-lying spots
and areas in northwest Wisconsin which received rain this
afternoon.

Cool air advection and cyclonic flow aloft persists on Saturday
with diurnally-driven showers and perhaps a rumble of thunder
possible. Temperatures trend cooler with highs in the low to
upper 60s. Gusty northwest winds are likely in response to the
strong flow aloft and steep low-level lapse rates. Look for
afternoon gusts of 20 to 30 mph with the strongest winds over
north-central Minnesota.

Chances for showers will continue for Sunday as the region
remains under cyclonic flow aloft from an area of low pressure
over James Bay. Thunder is unlikely with next to no CAPE and
overall less activity expected. With northwesterly flow, lake
enhanced showers Sunday will turn into lake effect showers for
Monday morning as high pressure nudges in from the west drying
out the region. Temperatures Sunday will remain on the cool side
in the 50s and 60s before warming Monday into the 60s and low
70s. Broad northerly to northwesterly flow will then prevail
into Friday with surface high pressure over the southeast CONUS.
Chances for showers and perhaps a few storms will return for
the latter half of the week as upper trough drops out of Canada.
Temperatures during this time will warm into lower to middle
70s.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 636 PM CDT Fri Aug 22 2025

A secondary cool front is creating a line of scattered showers
and some thunder across north-central MN. These have already
passed INL. As they pass through BRD in the next hour or two,
some thunder can`t be ruled out. Recent trends suggest HIB will
probably just see showers, so thunder was left out of the TAF
there. These showers should eventually pass through DLH and
possibly HYR later this evening as well, though they may fizzle
out before they reach HYR. Visibility may briefly fall to MVFR
as these showers pass by.

Tonight, winds become steadily breezier from the northwest with
gusts up to 15 to 20 kt persisting through the period. Ceilings
will trend towards MVFR overnight into Saturday as an upper
level trough passes through. Scattered showers may create
temporary MVFR visibility and ceiling restrictions. There is
very low confidence on exact timing, but they should be numerous
enough that most terminals will be affected at least once or
twice mid-day into the afternoon.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 331 PM CDT Fri Aug 22 2025

Southwest winds are forecast this evening and will veer
westerly and increase tonight. Sustained winds of 10 to 15 knots
with gusts of 15 to 25 knots are forecast and will pose a risk
to smaller vessels. Winds will remain strong on Saturday before
weakening for a time Saturday night and Sunday morning. A Small
Craft Advisory is in effect from 10 PM tonight until 10 PM
Saturday.

Winds veer northwesterly by late Sunday morning and increase to
12 to 20 knots with gusts of 15 to 25 knots. Waves along
portions of the South Shore and Outer Apostle Islands will build
to 3 to 5 feet. Conditions will be hazardous to smaller craft
once again.

For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...Small Craft Advisory from 10 PM this evening to 10 PM CDT
     Saturday for LSZ121-140>148-150.

&&

$$

DISCUSSION...Huyck/BJH
AVIATION...JDS
MARINE...Huyck