251
FXUS63 KDLH 021132
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
632 AM CDT Sat Aug 2 2025

.KEY MESSAGES...

- Stagnant weather pattern remains in place with a strong high pressure
  over the region trapping smoke at the surface. Air Quality
  Alerts remain in effect across the Northland

- Pattern change begins Sunday with precipitation chances of
  20-30% entering from the west in the afternoon.

- A Rex blocking pattern sets up over the Northland leading to off
  and on rain and thunderstorm chances through the work week.

&&

.DISCUSSION...
Issued at 209 AM CDT Sat Aug 2 2025

Quiet weather persist today and through most of Sunday as an
impressive surface high pressure dominates the Upper Midwest.
Clocking in around 1030mb this anomalous pressure reading has a
return interval of 1 day in every 10 years. Aloft an upper level
ridge is also acting to keep any shortwave impulses at bay further
solidifying the stagnant weather pattern. The biggest story is the
smoke from the Canadian wildfires leading to poor air quality across
the region. Currently we have Air Quality Alerts out for all of
MN and WI. The MN one goes through till Monday with WI going
through Saturday. However, with the pattern being fairly
stagnant the WI one may need to be extended.

On Sunday the high pressure begins to weaken and shift off to the
east. Return flow on the backside of the air mass will bring
southerly winds into the region. The prolonged period of smoke
pouring in from the northwest will mean that these southerly winds
will likely still be infested with smoke.

With the return of southerly winds we will see an increase in
moisture advection and warming temperatures. Ridging aloft moves off
as well with some shortwaves moving in from the west. Cluster
analysis shows good agreement with high pressure forming over
Manitoba as a trough undercuts it to the south. Several deterministic
models favor an upper level low developing which would result in a
Rex Block over the Northland. Given our positioning within this
pattern we would see an increase chance of precipitation for several
days. The latest NBM guidance shows a 20-30% chance of rain
beginning late Sunday and persisting through the work week.

Convective parameter space is not overly impressive to start the
week with meager amounts of instability and non existent bulk shear.
Initial rounds of precipitation will likely be showers with a
few isolated storms possible, however, an inversion in the low
levels will keep things well capped based on the 00Z guidance.
Later in the week we start to build in some stronger instability
but the question will be how does the shear look for storms to
grow? This will largely be determined by the placement of the
upper level low in the blocking pattern. For now, the ingredients
are not lining up well. The CSU ML severe prob do begin to
light up on Wednesday when a stronger shortwave pushes in from
the west.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 624 AM CDT Sat Aug 2 2025

Smoke will continue to be the primary concern across the
Northland for this forecast cycle. Reduced visibilities this
morning are due to a mixture of fog and smoke, and expect
improvement over the next couple hours. Thereafter, Canadian
wildfire smoke will continue to reduce vis to MVFR through the
day.

Winds will be generally from the southwest today, less than
10mph, but could be light and variable at times.


&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 209 AM CDT Sat Aug 2 2025

Southwest winds are expected across the Lake today with speeds
around 5 to 10 knots. The far northeast point of Grand Portage may
see a brief stint of gusts up to 25kts this afternoon for a couple
hours. Wave heights are expected to remain less than 3 ft.
Additionally, reduced visibility from wildfire smoke will
persist.

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.

&&

$$

DISCUSSION...Britt
AVIATION...HA
MARINE...Britt