754
FXUS63 KDLH 171133
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
633 AM CDT Thu Sep 17 2026

.KEY MESSAGES...

- Areas of dense fog are possible this morning. A Dense Fog
  Advisory is in effect until 10 AM for portions of central and
  north-central Minnesota.

- Another round of showers will spread across the region early
  Friday and linger into Saturday morning. The heaviest rainfall
  (40-60% of 1") will be south of a line from Brainerd to
  Sandstone to Hayward to Park Falls.

- Dangerous swimming conditions expected for the beaches of the
  Twin Ports Friday and Saturday then again Sunday and Monday
  afternoons and evening.

&&

.DISCUSSION...
Issued at 337 AM CDT Thu Sep 17 2026

TODAY AND TONIGHT...

Light rain lingered over northwest Wisconsin east of a line
from Spooner to Mercer. Another band of showers was advancing
east-southeast along the North Dakota/Manitoba border east into
northwest Ontario. Between these two areas of precipitation a
wedge of clear skies was found. Areas of fog are anticipated
this morning as winds become light. The lowest visibility will
be found over areas that received rainfall Wednesday afternoon
and evening. We will monitor trends. A Dense Fog Advisory may
become necessary.

The light rain over northwest Wisconsin will push out of our
area by 7 AM while the northern band of showers sags southward
into the Borderlands and gradually dissipates by 10 AM.
Otherwise expect mostly sunny to partly cloudy skies today.
Highs will reach the middle 60s along the Canadian border to the
middle 70s in the St. Croix River Valley. Clouds spread
northward tonight ahead of an approaching low pressure system.
Rain chances will likely hold off until after 7 AM Friday due to
the influence of high pressure moving eastward across southern
Manitoba into northwest Ontario. More on that below.

FRIDAY AND SATURDAY...

Surface low pressure and associated shortwave trough will
propagate eastward from the South Dakota/Nebraska border to near
southern Lake Michigan by Saturday evening. A warm front will
lift northward across Iowa to near the Minnesota border and
stretch east into southern Wisconsin by Friday evening.
Isentropic ascent over the warm frontal zone will produce a
broad area of precipitation over southern and central Minnesota
stretching into northwest Wisconsin on Friday. The influence of
the northern surface high pressure will be most noticeable
through reinforcing dry air from north to south undercutting the
precipitation. Radar echoes are likely to over-represent the
northward extent of precipitation as the dry air evaporates the
rain before it can reach the ground. We continued the previous
shift`s concept of tightening the QPF and PoP gradient over
central Minnesota into northern Wisconsin.

NBM probabilities support the tight gradient of precip and
PoPs. The NBM probability of more than 1 inch of rain is
maximized south of our forecast area. There is a stripe of
40-60% chance of 1 inch or more south of a line from Brainerd to
Sandstone to Hayward to Park Falls. The 40% threshold for 0.5
is not much farther north and extends from roughly Pine River to
Moose Lake to Mellen to Mercer. The 40% chance of a tenth of an
inch extends from Walker to Two Harbors to Bayfield to
Ontonagon, MI. The distance of the 40% chance of 1 inch of rain
and a tenth of an inch is only about 60 miles.

Rain tapers off Saturday morning with a small portion of
northwest Wisconsin seeing a 30% chance of showers into the
early afternoon.

As the high and low pressure systems propagate eastward winds
over western Lake Superior will turn northeasterly and
strengthen Friday and remain strong Saturday. The highest wind
and waves will be in the southwest arm of Lake Superior which
will pose a risk of rip currents for the beaches of the Twin
Ports.

SATURDAY NIGHT THROUGH NEXT THURSDAY...

Another area of surface high pressure will propagate eastward
across the Canadian Prairies and northern Ontario over the
weekend. Rain chances Sunday have dwindled as the next area of
low pressure to our south has taken a more southerly trajectory
than earlier forecasts. A few sprinkles Sunday afternoon and
evening aren`t out of the question.

Cooler air, clear skies, and light winds will set the stage for
areas of fog and frost Sunday night and again Monday night.
Lows both nights are forecast in the low 40s to middle 30s.

Temperatures Sunday through Thursday will be near normal. They
will start out on the cool side of the normal range Sunday with
highs in the low 60s to around 70 degrees. Temps gradually warm
to the warm side of the normal range by Wednesday and Thursday
with highs in the middle 60s to low and middle 70s.

A chance of rain returns Wednesday night and Thursday, although
overall confidence is low at this time.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 632 AM CDT Thu Sep 17 2026

Areas of fog developed early this morning and should mix out by
15Z. Skies are expected to be partly cloudy today with light
winds. High stratus will begin to move into the Northland from
the south tonight. As of this morning it seems BRD, DLH, and HYR
will be overcast which will limit their potential for fog
development. HIB is expected to see fog Friday morning with IFR
to LIFR conditions. After 12Z Friday an area of rain will
advance northward and may produce lower ceilings and visibility
at BRD, DLH, and HYR.

&&

.MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 337 AM CDT Thu Sep 17 2026

East and southeast winds of 5 to 10 knots across western Lake
Superior today. Winds veer northeasterly and begin to strengthen
to 10 to 15 knots with gusts of 15 to 25 knots tonight in
response to surface high pressure moving eastward across
northern Ontario and developing low pressure near northeast
Colorado. Wind will become hazardous for smaller vessels. Small
Craft Advisories will eventually be needed. There is a chance of
light rain mainly over the southern half of the waters Friday
afternoon through Friday night. Winds will relax over most of
western Lake Superior Saturday with the exception of the
southwest arm and areas near the Outer Apostle Islands down to
Saxon Harbor. Saturday night through Tuesday will see a diurnal
decrease in wind speeds and gusts during the night through mid-
morning and then an increase in wind speeds late morning through
early evening. Additional Small Craft Advisories may be needed.
There is a 20% chance of gales to 35 knots over the eastern
Apostle Islands to Saxon Harbor Sunday afternoon.

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

&&

.FIRE WEATHER...
Issued at 337 AM CDT Thu Sep 17 2026

No fire weather concerns. Min RHs through the forecast period
remain above 40% with highs in the 60s and low 70s. Rain chances
will return early Friday morning and linger into Saturday
morning. Rain chances and amounts have been trending farther
south with time each day. As of this morning the heaviest rain
still looks to remain to our south but we do have a 40-60%
chance of seeing 1" of rain from southern Pine into Price
Counties. Totals taper off as you head north and there will
likely be a sharp gradient as dry air from Canada undercuts some
of the rain totals. Areas north of a line from Walker to Duluth
to Mercer are unlikely to see measurable rain.

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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Dense Fog Advisory until 10 AM CDT this morning for MNZ018-019-
     025-026-033>036.
WI...None.
MARINE...None.

&&

$$

DISCUSSION...Huyck
AVIATION...Huyck
MARINE...Huyck
FIRE WEATHER...Huyck