831
FXUS63 KDLH 260516
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1216 AM CDT Sat Jul 26 2025

.KEY MESSAGES...

- Wildfire smoke will linger over the Northland through this
  evening. Expect hazy skies and reduced visibility.

- A hot and humid weekend with heat indicies in the 90s Saturday
  and Sunday. A Heat Advisory was issued for Saturday. Another
  will likely be needed Sunday and perhaps Monday.

- There is a chance of storms Saturday afternoon into Saturday
  night. Locally heavy rain is not out of the question with
  these storms.

- There is a greater chance (60 to 70 percent) for more
  widespread and intense thunderstorms capable of producing
  heavy rainfall Sunday afternoon into Sunday night. There is a
  15 to 25 percent chance flash flooding occurs in the
  Northland.

- Less humid and slightly cooler Tuesday through the end of next
  week.

&&

.DISCUSSION...
Issued at 423 PM CDT Fri Jul 25 2025

Summary...

A less active period is on tap over the next several days.
There are a few chances of storms tonight, Saturday afternoon
and evening, and Sunday afternoon and night. A few storms may be
strong Sunday and Sunday night. There is also a risk of heavy
rainfall which may lead to flash flooding. Quieter weather is on
tap for Monday through the end of next week with slightly
cooler temperatures expected.

Tonight through Saturday night...

A broad area of surface high pressure and building mid-level
ridging over the Northland will keep skies partly cloudy to
mostly clear tonight. A few sprinkles may occur over northern
Itasca and southern Koochiching counties this evening. A few
taller cumulus were noted on GOES-East imagery this afternoon
with weak radar echoes. Wildfire smoke will continue to advect
northward this evening. Satellite imagery revealed the smoke
extended well south into the northern Twin Cities and west-
central Wisconsin. Therefore visibility will be slow to improve
this evening as smoke continue to lift northward. Expect smoke
to clear late tonight.

Storms are expected to develop this afternoon and evening over
the northern High Plains and will generally ride the upper-level
flow northeasterly toward northern Minnesota late overnight. A
few storms may hold together and move into north-central
Minnesota after 3 AM. Should storms remain intact, they may
propagate eastward with time north of the Iron Range Saturday
morning.

Aside from the potential for ongoing storms early Saturday
morning, there will be a chance of storms developing Saturday
afternoon and evening. Ample MLCAPE of 1500-2500 J/kg is
forecast by 26.21Z. Convergence will be hard to come by and may
be driven by remnant outflow boundaries from overnight
convection. Deep layer shear of 25 to 30 knots seems to preclude
a risk of organized severe storms. Pulse storms will likely be
the mode de jure. Brief heavy rainfall and hail up to half
dollar size (1.25 inches) will be the main concern. There may be
sufficient dry air in the lowest 300 mb to support a microburst
threat.

High temperatures will be in the low to upper 80s with heat
indices in the low 90s. Local heat risk guidance suggests a
higher than average risk of heat illness Saturday afternoon and
therefore we have issued a Heat Advisory for nearly all of the
Northland from noon until 8 PM Saturday.

Afternoon storms may percolate into the evening. There is a
small chance (about 5%) that merging cold pools by mid to late
evening may support a brief risk of upscale growth and a slight
increase in damaging wind potential. More likely is that the
storms will remain disorganized and will gradually weaken
through the evening as daytime heating is lost.

Sunday through Monday...

Another warm day is on tap for Sunday. High temperatures will
range from the low 80s north to the low 90s south. Heat indices
are forecast in the 80s to upper 90s. A few spots in the St.
Croix Valley may reach the low 100s for heat index values.
Another Heat Advisory will likely be needed. Any lingering
convection or cloud cover will have an impact on those
temperatures and the heat risks and the affected areas may
change.

A cool front will sag southeastward on Sunday and should
provide enough low-level convergence for thunderstorms to
develop. MLCAPE values ahead of the front are forecast in the
2000-3000 J/kg range. Shear will once again be a limiting factor
(much like earlier this week). Deep layer shear on the order of
25 to 30 knots will translate into pulse storms. Hail, damaging
downburst winds, and torrential rainfall are the main threats.
The Storm Prediction Center has outlined the area in a Marginal
Risk (1 out of 5) for severe storms Sunday afternoon and
evening.

WPC has northern Minnesota and portions of northwest Wisconsin
in a Slight Risk of excessive rainfall. PWATs are forecast to
climb into the 1.5 to 2.0 inch range with the highest values
over areas west of a Kabetogama to Duluth to Pine City line.
Moisture transport vectors lengthen ahead of the front Sunday
night as the nocturnal low-level jet develops. Low-level winds
will be oriented roughly parallel to the front which will
support training storms and heavy rainfall. Given the heavy
rainfall over portions of northeast Minnesota over the past week
or so, a Flood Watch may eventually be warranted.

Storms will weaken and move out of the region early Monday
morning. There is a small chance of another round of storms
Monday afternoon and evening if the front is still nearby at
that time.

Tuesday through Friday...

A broad Southeast US mid-level ridge is forecast to retrograde
toward the southern Rockies early next week. This will keep the
subtropical jet north of us across the Canadian Prairies. Quasi-
zonal to northwest flow aloft will bring a period of quieter and
cooler weather. Smoke may return to the region due to the
northerly wind trajectory, although time will tell how
significant those impacts will be.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 618 PM CDT Fri Jul 25 2025

Not much change, just pushed tstorm timing back a few hours at
KINL. Canadian wildfire smoke lingers slowly clear out tonight.
Fog builds into area terminals tonight and mixes with the smoke
and is expected to create a few hour period of IFR visibility.
A round of thunderstorms moving into north- central Minnesota
may impact terminals north of the Brainerd Lakes. Southwest
winds Saturday gust to 20 knots.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 423 PM CDT Fri Jul 25 2025

Main concerns for western Lake Superior over the next several
days will be a few thunderstorm chances Saturday afternoon and
Sunday night through early Monday morning. A few storms may be
strong with wind gusts up to 35 knots and small hail. Frequent
cloud-to-water lightning, locally higher waves, and torrential
rain which would reduce visibility to less than 1 mile are the
other hazards. Winds away from storms will be less than 15
knots.

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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Heat Advisory from noon today to 8 PM CDT this evening for
     MNZ010>012-018-019-025-026-033>038.
WI...Heat Advisory from noon today to 8 PM CDT this evening for
     WIZ001>003-006>008.
MARINE...None.

&&

$$

DISCUSSION...Huyck
AVIATION...NLy/Wolfe
MARINE...Huyck