675
FXUS63 KDLH 151139
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
639 AM CDT Tue Sep 15 2026

.KEY MESSAGES...

- Hazardous marine conditions today with gale force wind gusts
  and high waves across western Lake Superior. Wind and waves
  diminish this afternoon and tonight.

- Additional rain chances late Wednesday/Wednesday night and
  again Friday into early Saturday. The late week system could
  bring an inch or more of rainfall south of a line from near
  Brainerd to Moose Lake to Bayfield.

- Near-normal high temperatures in the mid 60s to low 70s for
  the later half of the week.

&&

.UPDATE...
Issued at 631 AM CDT Tue Sep 15 2026

Shallow pre-frontal convection developed since 09Z over portions
of northern Minnesota. Expect the convection to continue to
expand south with time in response to height falls and a few
hundred J/kg of MUCAPE. Added a 20% chance of showers with that
line for the next few hours. Remainder of forecast appears to be
on track.

&&

.UPDATE...
Issued at 257 AM CDT Tue Sep 15 2026

Vertically stacked low pressure centered over southeast
Manitoba will propagate rapidly northeast to James Bay by 00Z
Wednesday. Low stratus and areas of drizzle over the Northland
early this morning are expected to clear as drier air advances
east in the stratospheric air intrusion located over western
Minnesota into southeast North Dakota and eastern South Dakota
as of 07Z this morning. Temperatures actually trended a few
degrees warmer over the past few hours in central and portions
of north-central Minnesota on the western periphery of the low
stratus. Farther west veering winds were found and remained
gusty early this morning. Higher altitude clouds closer to the
low center were over most of eastern North Dakota and Manitoba.

Expect a wedge of clearing to spread eastward across the
Northland this morning which will be followed by the not-quite-
as-low stratus closer to the low center. Raised early morning
low temps a few degrees in response to this warming and the
prolonged persistence of the low cloud deck. Drizzle and fog
will gradually push eastward as drier air undercuts the low
stratus. Temperatures today will be warmer than yesterday due in
large part to the increased sunshine. Highs will range from the
low to upper 60s. A few spots in the St. Croix River Valley may
see low 70s.

High pressure will drift across the region tonight and provide
light winds and efficient radiational cooling. With the recent
rainfall, temps may not plummet quiet as efficiently as Sunday
night/early Monday morning. Even so, a decision was taken to
nudge temperatures tonight a little colder, below the NBM 10th
percentile guidance in many areas. Look for overnight lows in
the middle to upper 40s along the Lake Superior shore in
northwest Wisconsin while areas inland (including inland
locations of the Bayfield Peninsula) will drop into the low 40s
to middle 30s. Frost Advisories may be needed once again tonight
should these trends persist.

Remainder of the forecast is essentially on track. Details are
located below.

&&

.DISCUSSION...
Issued at 315 PM CDT Mon Sep 14 2026

Wednesday - Thursday:

A zonal flow pattern aloft sets up for Wednesday and Thursday.
Wednesday will be dry to start, but there is potential for some
light rain showers (10-40%) across far northern and southern
portions of the Northland Wednesday evening into early Wednesday
night as the high pressure departs to the east. An additional
surface high pressure center passing to our north Thursday
should keep that day dry.

Temperatures moderate slightly for Wednesday and Thursday with
high temperatures in the mid 60s to low 70s on
Wednesday/Thursday, and some mid 70s in the Brainerd Lakes to
northwest Wisconsin on Thursday. Relatively warmer lows in the
40s to low 50s (warmest near Lake Superior) Wednesday and
Thursday nights should keep any additional frost chances at bay.

Friday - This Weekend:

Another round of showers and thunderstorms are forecast to
return to the Northland on Friday through early Saturday. Lee
cyclogenesis develops a surface low in eastern Colorado on
Thursday and ejects it through the Central Plains Thursday
night/early Friday and into the Upper Mississippi River Valley
late Friday into early Saturday. The exact track of the surface
low and the northward extent of its attendant warm front and
warm sector will dictate precipitation potential, amounts, and
locations in the Northland for Friday through early Saturday.
The ECMWF EFI QPF values with this system do show a swath of
0.5-0.6 (out of a maximum of 1) into portions of inland
northwest Wisconsin along with 90th-plus percentile PWATs
relative to NAEFS CFSR climatology, suggesting potential for an
unusually higher than normal precipitation signal from several
EPS members for this time of year. All this is to say that if
the surface warm front sets up in the ideal location just south
of the area, a low-level jet riding over to the cool side of the
front could set up a band of heavier rainfall in southern
portions of the Northland, particularly northwest Wisconsin. The
WPC Day 5 Slight Risk area also highlights this potential for
heavy rainfall. Additionally, the 13Z 9/14 run of the NBM
rainfall amount probabilities for 0.5" or greater are 50-75%
south of US-2, highest in inland NW WI, but don`t drop off much
for 1" or greater with probabilities still 40-65% for the same
areas.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 631 AM CDT Tue Sep 15 2026

Low stratus remained over portions of the eastern Arrowhead and
northwest Wisconsin. Expect clearing to move into those areas
over the next hour or two. Stratus associated with the upper low
a little farther west was mainly revealing VFR ceilings
dropping to MVFR over northwest Minnesota. Following the VFR
trend for now. Think diurnal heating may help erode the cloud
bases and keep them VFR as they move east. Low-level wind shear
persist ahead of a secondary cold front pushing east through
northeast Minnesota as of 1130Z. Look for wind shear risk to
decrease quickly with frontal passage. A few convective showers
developed ahead of the front since 09Z and should persist and
move generally northeastward over the next several hours. There
is a very low chance of lightning (around 2%) with those
showers. High pressure will drift over the Northland tonight
providing clear skies and light winds. Fog and mist may develop
early Tuesday morning. There may be vertical visibility in the
LIFR range if fog becomes thick. The caveat to fog/mist is the
potential for frost to rob moisture from the air and maintain
sufficient dewpoint depressions overnight.

&&

.MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 257 AM CDT Tue Sep 15 2026

Surface low pressure over southeast Manitoba will quickly move
to near James Bay by this evening. Winds will veer westerly and
perhaps northwesterly and are expected to strengthen through
late morning into early afternoon. Gales of 35 to 45 kts begin
to develop by 12Z (7 AM CDT) and will persist through early
afternoon. Winds and waves will quickly diminish this afternoon
into early evening. Small Craft Advisories and Gale Warnings are
in effect for much of today. It is likely there will be a short
period of time late Tuesday afternoon into early evening when
Small Craft Advisories will be needed after the Gale Warnings
end. Winds and waves will become light Tuesday night and persist
at 15 knots or less for Wednesday and Thursday. Another storm
system will move through the region Friday and Saturday which
will bring another period of stronger winds and higher waves.

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

&&

.FIRE WEATHER...
Issued at 257 AM CDT Tue Sep 15 2026

Fire weather concerns remain low through the forecast.
Widespread wetting rain occurred Monday. Minimum relative
humidity values will generally stay above 45 percent the next
few days. West winds are forecast today at 10-20 mph with gusts
as high as 30 to 40 mph. Winds will diminish for the remainder
of the week. There will be a few more chances of rain this week
with the greatest potential during the Thursday night through
Saturday morning period.

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 4 PM CDT this afternoon for LSZ121.
     Small Craft Advisory until 7 AM CDT this morning for
     LSZ140>148-150.
     Gale Warning until 4 PM CDT this afternoon for LSZ140>148-150.

&&

$$

UPDATE...Huyck
DISCUSSION...Rothstein
AVIATION...Huyck
MARINE...Huyck
FIRE WEATHER...Huyck