993
FXUS63 KDLH 010550
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1250 AM CDT Mon Sep 1 2025

.KEY MESSAGES...

- Warm weather with scattered showers and storms through tonight
  Day that could bring localized heavy rainfall.

- Areas of fog overnight.

- Thunderstorms are possible with a cold front Tuesday and
  Tuesday night.

- Cooler temperatures and scattered rain showers expected
  Wednesday through the rest of the week.

- Frost Advisories may eventually be needed if winds calm down
  and skies clear Thursday morning with widespread lows in the
  30s.

&&

.UPDATE...
Issued at 1250 AM CDT Mon Sep 1 2025

"Fog Watch 2025" continues early this morning with high
pressure, light winds, and mainly clear skies. Hibbing, Bigfork,
Cook, Longville, Aitkin, McGregor, Moose Lake, Hayward,
Ashland, Solon Springs, and La Pointe all reported reduced
visibility in the past hour. International Falls had visibility
as low as 1 mile. Will keep an eye on trends overnight. A Dense
Fog Advisory may eventually be necessary. Showers Sunday
afternoon likely enhanced low-level moisture available for fog
formation and skies are generally clear as of 0530Z. The surface
pressure gradient is a little tighter than the past few nights,
so winds may not be completely calm. ASOS and AWOS stations
aren`t able to detect wind speeds less than 3 knots, though
nearby RAWS sites and CWOP stations can. Any fog which develops
should dissipate by 9 AM.

The other trend to monitor early this morning remains the
potential for isolated showers and perhaps a few brief storms.
The 01.04Z RAP features weak isentropic ascent over the
Arrowhead into portions of north-central Minnesota. Similar to
Saturday morning, there will likely be a few showers which
percolate over those areas early this morning. A few of the CAMs
(NAMNest, HiResW-ARW, HiResW-FV3, and the NSSL-WRF) suggest an
increase in coverage and intensity along the North Shore to the
Twin Ports through 01.12Z. Added some broad brushed sprinkles to
the forecast and held onto the previous areas of showers with
this update.

&&

.DISCUSSION...
Issued at 154 PM CDT Sun Aug 31 2025

A complex forecast is unfolding for the Northland for this
afternoon in a very low forced environment. A persistent and
slow-moving band of showers is exiting the Twin Ports though it
brought over an inch of rain in its wake. While the atmospheric
setup doesn`t seem the best setup for heavy rain...high moisture
content, low freezing levels, and subtle low-level convergence
are all contributing to its formation. As this relatively small
spatial area of showers slowly tracks southwest, some areas
could see rainfall totals exceeding an inch, and locally heavy
downpours are possible as redevelopment occurs along the North
Shore this afternoon.

Looking ahead, most places should see a mix of sun and clouds
to start the afternoon, with temperatures climbing into the
mid-70s to low-80s though lower values underneath the areas that
received rainfall this morning. Daytime heating will create
enough instability to support isolated to scattered showers and
thunderstorms, especially over the Arrowhead region. Given the
weak steering winds, storms will be slow-moving and could
continue to produce brief periods of locally heavy rain.
However, the overall setup doesn`t favor severe weather, as weak
winds aloft will result in more of a pulsing, non-organized
storm mode. While most of the Northland will remain dry, some of
the heaviest showers could drop 1 to 3 inches of rain with high
resolution guidance hinting at this very heavy localized threat
albeit a small chance of it. With hodographs showing very
little flow throughout the depth of the atmosphere, storms that
do pop won`t move much. This at least warrants a high pop
forecast than NBM with higher QPF even though we may not get the
exact area right. These chances for isolated showers and
thunderstorms will continue overnight, although a general
downward trend in coverage is expected, so again went quite a
bit higher than NBM. Patchy fog may also develop where skies
clear and winds calm.

Labor Day will bring a return of weak southerly winds, which
will once again provide enough moisture and instability to fuel
afternoon isolated to scattered showers and thunderstorms.
Temperatures will be similar to today, reaching the mid-70s to
low-80s. Storms will again be slow-moving, increasing the
potential for localized heavy rainfall, but the overall threat
for severe weather remains low.

Our next significant change in the weather pattern arrives on
Tuesday as a cold front sags southward across the Northland,
bringing a good chance for showers and thunderstorms. While some
of these storms could be strong, the severe threat remains low
due to limited instability and weak winds aloft. The main event,
however, is the closed upper-level low that will settle over
the western Great Lakes on Wednesday and remain through the end
of the week. This will usher in a taste of autumn, with highs
struggling to get out of the 50s and low-60s from Wednesday
through Saturday. Widespread clouds and scattered showers will
be a consistent theme during this period. The combination of
cold air and cyclonic flow aloft could even lead to a few of the
seasons first snowflakes mixing in with the rain, especially
during Wednesday and Thursday nights across northern Minnesota.
Additionally, the colder temperatures could necessitate Frost
Advisories if skies clear and winds calm down.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1250 AM CDT Mon Sep 1 2025

The main concern through 14Z will be the fog and reduced
visibility at the terminals. A few rain showers may develop
around HIB, INL, and DLH. HIB and HYR both saw variable
visibility between 04Z and 0530Z. INL reported IFR visibility
for runway 31. All signals point to IFR visibility at the
terminals overnight. There are two mitigating factors, wind
speeds between calm and 3 knots (which are all recorded as calm
at the ASOS), and the potential for stratus development in the
4-8 kft layer. The former may be discernible using nearby non-
ASOS stations and the latter would be associated with shower
development. Confidence in the visibility forecast is high as
both mitigating factors have much lower chances of occurring.

After 14Z the atmosphere will be favorable for diurnal Cu and
showers. A thunderstorm or two is not out of the question. Given
the low overall chance of impacts at the terminals, opted for a
dry forecast. Visibilities should dip into the MVFR to LIFR
range again after 02.06Z. Showers, isolated storms, and gusty
winds are expected after 02.12Z as a cold front propagates
southeastward across the region.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 154 PM CDT Sun Aug 31 2025

High pressure will remain in place over the region for the next
few days. This will keep winds generally less than 10 knots
from the southwest. Isolated showers and storms are likely today
and tonight particularly near the North Shore.

A cold front is forecast to move southeastward across western
Lake Superior on Tuesday. Showers and thunderstorms are expected
with the front and winds will veer northwesterly and increase
in speed behind the front. Conditions will become hazardous for
small craft from Wednesday morning through Thursday morning.

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...None.

&&

$$

UPDATE...Huyck
DISCUSSION...Wolfe
AVIATION...Huyck
MARINE...Wolfe