656
FXUS63 KDLH 171743
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1243 PM CDT Mon Aug 17 2026

.KEY MESSAGES...

- Patchy fog, occasionally become locally dense, is expected to
  dissipate after sunrise. Cloud cover will be increasing later
  this morning into the afternoon.

- Showers and thunderstorms arrive this afternoon and evening
  along a cold front. A few storms may be strong to severe,
  especially in the Brainerd Lakes area. Potential hazards
  include damaging winds up to 60 mph and large hail up to 1
  inch in diameter.

- Dry and cooler weather is forecast for Tuesday into Wednesday,
  with additional rain chances and slightly warmer temps late in
  the workweek.

&&

.UPDATE...
Issued at 422 AM CDT Mon Aug 17 2026

Mostly clear skies allowing for diurnal cooling combined with light
winds has produced patchy fog early this morning. Visibility
has been trending slightly lower since the previous discussion
update, with isolated areas of 1/2 mile visibility occasionally
occurring. Will continue to hold off on issuing a Dense Fog
Advisory this morning due to the dense fog coverage being too
isolated and duration being too intermittent. Fog is still
expected to dissipate just after sunrise this morning as diurnal
heating begins.

The forecast for this afternoon is still on track with the previous
update. Timing for showers and thunderstorms developing along an
approaching cold front is still expected to be the afternoon into
the early evening, which will coincide with peak diurnal heating.
The southwestern portion of the CWA remains under a Marginal Risk
(Level 1 out of 5) Outlook from SPC today, with a small northward
expansion of the Marginal Risk occurring this morning. Potential
severe hazards will be damaging winds up to 60 mph and large hail up
to 1 inch in diameter.

Following the cold frontal passage tonight, cooler temperatures
filter into the CWA for Tuesday into Wednesday. Frost is not
anticipated on Tuesday night into early Wednesday morning, but
expect chilly low temperatures in the 40s with a few upper 30s
possible. The forecast for the latter half of the week remains
on track since the previous forecast update.

&&

.DISCUSSION...
Issued at 155 PM CDT Sun Aug 16 2026

Plenty of clouds with a few embedded sprinkles is the story of
this Sunday. Drier air is filtering in from the northwest with a
surface high moving in from the west. Therefore, expect
gradually clearing skies this afternoon and mostly clear skies
overnight. We will probably get some fog to develop with good
radiational cooling conditions. Models are pretty solid on
having fog in the usual low-lying inland areas. The probability
for visibilities less than 1 mile are generally 20% or less, so
we will probably see some patchy dense fog, but perhaps not
enough coverage to warrant any Dense Fog Advisories. Expect fog
to lift/mix out just after sunrise Monday morning.

Monday afternoon into Monday night, another cold front is
expected to make its way through from northwest to southeast.
We`ll have sufficient moisture for some thunderstorms with PWATs
in the 1-1.5" range. Good synoptic support for lift with the
front itself and an upper-level trough aloft. Convective
parameters are so-so for any strong/severe storms. The timing of
this has trended earlier such that we may catch the peak diurnal
heating Monday afternoon and end up with ~1000 J/kg or so of
MUCAPE, at least in northeast Minnesota. Not much for low-level
directional shear with southwest flow expected ahead of the
front. Some drier air aloft ahead of the front could produce a
small risk for strong wind gusts. All said, we`ll be looking at
widespread showers and storms likely Monday afternoon and night,
generally weakening a bit as they move into northwest
Wisconsin. A few storms could be on the strong side with some
small hail and gusty winds, and a stray severe storm can`t be
ruled out with low-end strong winds or quarter size hail being
the main threats.

Expect the front to be out of here Tuesday morning, leaving us
with northwest flow and some slightly cooler temperatures (highs
in the 70s). Tuesday night might be on the chilly side with lows
in the 40s likely and perhaps some stray upper 30s not out of
the question for the usual cold spots. High pressure sticks
around into Wednesday, keeping the weather quiet. Southerly
return flow will likely develop Thursday, and we`ll be watching
for another cold front to be making its way here by around
Friday. We could see another round of showers and storms with
this. At this time, convective parameters look rather dull for
anything strong/severe, but that could change.

The pattern is looking very pre-fall next weekend with northwest
flow following the cold front. Some lingering instability
showers can`t be ruled out Saturday, but otherwise the weather
looks pretty quiet. One might be tempted to call this fall-like
weather, but with temperatures still looking to be in the 70s to
around 80 for highs, it should still be feeling more like late-summer
weather.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1242 PM CDT Mon Aug 17 2026

The main hazard this afternoon and evening will be thunderstorm
potential as a cold front passes through. Storms are expected to
pass over each terminal from northwest to southeast, though
thunder is least likely at INL because storms could form more
south of there. Strong to severe storms can`t be ruled out with
strong and erratic winds and small to perhaps quarter sized hail
possible. After the storms, winds become northwesterly tonight.
Models are in pretty good agreement that there should be some
fog developing, especially where it rains. Dense fog is
definitely possible for a few hours in the late night/early
morning Tuesday period. Expect fog to mix out Tuesday morning,
leading to VFR conditions for the rest of the period.

&&

.MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 422 AM CDT Mon Aug 17 2026

Breezy southwest winds ahead of a cold front are expected this
afternoon along the North Shore. The Small Craft Advisory that was
in effect from Grand Marais to Grand Portage has been expanded to
now include nearshore waters from Grand Marais to Silver Bay, as
there is the potential for wind gusts to 25 knots for several hours
this afternoon.

Showers and thunderstorms arrive along the aforementioned cold front
this afternoon and evening, although severe thunderstorms are not
expected. Expect winds to shift to the northwest tonight following
the cold front, with winds generally trending lighter heading into
mid-week as high pressure builds.

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

&&

.FIRE WEATHER...
Issued at 422 AM CDT Mon Aug 17 2026

Clear skies will start off today, with southwest winds gusting 15 to
20 mph this afternoon ahead of an approaching cold front. Expect
cloud cover to increase from west to east through the day, with
northwest WI seeing the driest min RH this afternoon in the 33-39%
range due to clouds not arriving until later in the day. Scattered
to widespread showers and thunderstorms will be moving through this
afternoon and evening, with wetting rains of 0.25" or greater being
hit or miss under individual thunderstorm cores. A few storms may
become strong to severe, especially in north-central MN, with gusty
and erratic wind gusts up to 60 mph and hail to 1" in diameter being
primary hazards.

Winds shift to the northwest tonight and high pressure builds on
Tuesday into Wednesday, bringing cooler temperatures and drier min
RH for mid-week. While critically dry min RH is not anticipated at
this time, areas of min RH as low as 30% will be possible each
afternoon from Tuesday through Thursday. Additional chances for
showers and thunderstorms arrive late Thursday into Friday as
another cold front moves into the area.

See the Fire Weather Forecast product for a more thorough
breakdown of fire weather conditions.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...Small Craft Advisory until 10 PM CDT this evening for
     LSZ140>142.

&&

$$

UPDATE...Unruh
DISCUSSION...JDS
AVIATION...JDS
MARINE...Unruh
FIRE WEATHER...Unruh