050
FXUS63 KDLH 051437
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
937 AM CDT Fri Sep 5 2025

.KEY MESSAGES...

- Breezy and even cooler today in the wake of the clipper with
  northwest winds gusting to 25-30 mph with a few spots gusting
  to 40 mph along with scattered light rain showers and
  sprinkles.

- Cooler, below-average conditions continue into this weekend.
  Areas of frost remain possible each night from tonight through
  Sunday night, but a widespread freeze is unlikely.

- Warming up back towards normal temperatures for mid-September
  next week, with highs in the mid 60s to low 70s.

&&

.DISCUSSION...
Issued at 411 AM CDT Fri Sep 5 2025

Today - Tonight:

The surface low pressure that brought rain showers to much of
the Northland yesterday has now moved into the U.P. of Michigan,
with some light showers in NW WI expected to exit towards
sunrise today. However, colder cyclonic flow on the backside of
a vertically stacked low in northern Ontario along with some
more subtle embedded shortwave energy should keep some scattered
showers/sprinkles ongoing today before ending west to east as
the evening progresses. There will be some mixing going on in
the lower atmosphere given a tight pressure gradient, which
will kick off gusty northwest winds today into this evening,
with gusts of 20-30 mph and even some occasional gusts to 40
mph during the daytime hours due to enhancement from mixing and
showers bringing down momentum from stronger winds above the
ground. This mixing could also result in some evaporation of
rain in the showers, so many locations may just see virga
instead of accumulating precipitation, particularly in central
to east- central MN. The colder airmass in place over a warm
Lake Superior and larger interior MN lakes should also lead to
some lake-effect rain showers today into tonight, as well.

High temperatures today (mid 40s to mid 50s) will be about 20F
below normal given the colder airmass, cloud cover, and rain. If
the forecast highs hold, several locations could see new record
cold high temperatures for September 5th set today (see
"Climate Section" below). Low temperatures are once again
forecast to drop into the mid 30s to low 40s tonight, coldest in
the Iron Range and areas north. There is still some question to
how quickly winds weaken into tonight and how much/where cloud
cover will be hanging around, but the coldest areas could see
some areas of Frost. A Frost Advisory may be needed for these
coldest areas, but probabilities for widespread freezing
temperatures remain low (less than 30%).

Saturday - Saturday Night:

A bit more of a mix of clouds and sun on Saturday rather than
cloudy like today will be. This should allow highs during the
day to warm slightly into the mid 50s to around 60 degrees.
While winds won`t be quite as strong on Saturday (daytime gusts
to 15-20 mph), mixing of the lower atmosphere will be even
deeper than on Friday. This is important to keep in mind as
vorticity with another mid/upper-level shortwave will be diving
across the Northland during the afternoon into early evening,
leading to additional potential for isolated to scattered light
showers and perhaps a few embedded rumbles of thunder. Given the
drier air, very little in the way of rainfall accumulations are
expected.

Saturday night looks like the best chance to see widespread
frost potential in the Northland as skies should become mostly
clear to partly cloudy and winds become light as surface high
pressure moves into the region. NBM probabilities for a freeze
(low temperature of <32F) seem slightly overzealous at the
moment, but still show areas of 20-50% probabilities for areas
of temps hitting 32F or less across north-central MN, portions
of the Arrowhead, and interior NW WI. These probabilities do not
appear to be widespread at the moment, however, and will need
to be monitored for changes. For reference, the deterministic
low temperature forecast currently is 33-37F in these same areas
for Saturday night.

Sunday - Sunday Night:

A warming trend begins on Sunday as an upper-level ridge begins
sliding into the front range of the Rockies and into the High
Plains. Expect dry conditions and highs in the upper 50s to mid
60s for Sunday with the surface high pressure still lingering
in the region. One more night with pockets of temperatures
dipping into the mid-upper 30s and lows elsewhere in the low 40s
will occur Sunday night, but the potential for frost doesn`t
appear as widespread as Saturday night.

Next Week:

The warming trend towards near-normal temperatures for mid-
September in the mid 60s to low 70s returns for much of the next
work week as the aforementioned ridge moves into the central
CONUS, but becomes dampened by a shortwave glancing the Upper
Midwest late Monday into Tuesday. Return flow/moisture
interacting with a warm front and surface low associated with
this trough should bring the next potential for showers and
thunderstorms. Otherwise, most of next week remains dry until
global model ensembles depict a more robust shortwave trough
traversing the northern CONUS into the Upper Midwest next Friday
into early next weekend with another shot at showers and
thunderstorms.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 633 AM CDT Fri Sep 5 2025

Ceilings across the area will largely be MVFR with a few
pockets here and there of VFR through much of today. Ceilings
will be slow to lift, but should gradually return to VFR this
evening through the end of the TAF period. Scattered light rain
showers and sprinkles persist across much of the area today into
this evening before decreasing tonight, with the best potential
at KINL/KHIB. Can`t rule out some patchy fog potential tonight
at KHIB. Have included MVFR visibility mention for now, but
there is roughly a 10-20% chance for IFR or lower visibility if
clouds can scatter out enough tonight.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 930 AM CDT Fri Sep 5 2025

Upgraded to a Gale Warning from Port Wing to Sand Island and for
the Outer Apostle Islands today and tonight for northwest wind
gusts to 35 kts and waves of 4 to 8 feet. Elsewhere, a Small
Craft Advisory remains in effect today and into tonight for
wind gusts of 25 to 30 kts, and waves of 1 to 3 feet along the
North Shore and 2 to 5 feet for areas not in the Gale Warning on
the South Shore. There is a 30 to 40 percent chance of Gale
Force wind gusts of 35 to 40kts along the North Shore this
afternoon and evening, especially from Taconite Harbor to Grand
Marais to Grand Portage, with stronger winds off of the
terrain.


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 until 5 AM CDT Saturday for LSZ121-140-
     141-147-148.
     Small Craft Advisory until 1 AM CDT Saturday for LSZ142>145.
     Gale Warning until 5 AM CDT Saturday for LSZ146-150.

&&

$$

DISCUSSION...Rothstein
AVIATION...Rothstein
MARINE...PA