573
FXUS63 KDLH 181946
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
246 PM CDT Fri Jul 18 2025

.KEY MESSAGES...

- Widespread showers with embedded thunderstorms continue today
  through tonight. Severe thunderstorms are not expected.

- Primarily dry weather returns this weekend once rain departs
  Saturday morning, though smoke aloft and at the surface should
  make it hazy with reduced air quality. High temps this
  weekend will be in the mid 70s to around 80.

- An active pattern returns to the area starting on Sunday
  night, with multiple rounds of showers and thunderstorms
  through next week.

&&

.DISCUSSION...
Issued at 245 PM CDT Fri Jul 18 2025

Today - Tonight:

Generally zonal flow aloft today with a weak 500 mb shortwave
trough moving through the flow across the Northland. PWATs of
1-1.5" move in with this shortwave trough later this afternoon
into tonight, with the highest moisture south of US-2. Expect
widespread showers and some embedded thunderstorms currently
over northern Minnesota and Lake Superior to gradually
overspread the remainder of the Northland later this afternoon
through tonight before exiting from west to east early to mid
Saturday morning. Despite 0-6 km shear around 50-55 kt,
instability (MUCAPE) should only be on the order of 200-700 j/kg
along and south of US-2, so any thunderstorms that do develop
should be largely isolated in nature and remain non-severe.
There is some higher DCAPE values and modest mid-level lapse
rates up to 6.5 C/km that may get into the Brainerd Lakes to
inland NW WI counties tonight, so can`t rule out an isolated
storm in those locations becoming strong with small hail. Storms
should be elevated in nature above the nocturnal surface
inversion, so it should be difficult for any stronger winds to
mix down to the surface. As for rain, generally expect most to
see light to moderate rain, through some localized amounts up
to around 1" of total accumulations from today through early
Saturday are possible for locations that see the embedded
thunderstorms as suggested in the 12Z HREF localized
probability-matched mean 24-hour precipitation (7 AM today-7 AM
Saturday window).

This Weekend:

After the rain moves out Saturday morning, some clearing skies
and predominately dry conditions should arrive for most of this
weekend. Temperatures should be around average in the mid 70s to
around 80 degrees for Saturday and Sunday. There is some lower
confidence potential for decaying showers from North Dakota to
move into north-central and northeast Minnesota on Sunday
morning into early afternoon, but drier air near the surface may
keep this activity as virga and keep it from reaching the
ground. Otherwise, the main weather concern this weekend would
be Canadian wildfire smoke spreading south into much of the
Northland Saturday afternoon and lingering into Sunday,
resulting in deteriorated air quality and hazy
conditions/reduced visibilities at times due to the smoke. An
Air Quality Alert (AQA) has been issued for all of our north-
central, east-central, and northeast Minnesota counties from 1
PM Saturday through 9 AM on Monday. The air quality is forecast
to get into the "Very Unhealthy" category. More details can be
found in the AQA. This smoke is forecast to exit back to the
north Monday morning as southeast surface winds become
established.

Sunday Night - Mid Next Week:

Broad upper-level ridging builds across much of the CONUS during
this timeframe as a prominent summertime mid/upper-level high
pressure center becomes established over the southeastern
CONUS. This will leave the Upper Midwest and Northland on the
northern fringe of the upper-level ridge where the upper-level
jet stream and periodic, embedded shortwave troughs will be
moving across our vicinity. This will bring several chances for
showers and thunderstorms from Sunday night through Tuesday
night. Some of these rounds could become strong to severe storms
with some heavy rainfall potential as return flow off of the
western Gulf pumps 1.5"+ PWATs back into the Northland, with
dewpoints climbing into the 60s to near 70F and a better
instability/shear combination than we are seeing with the
convection today. One thing of note is that the synoptic forcing
with the shortwave troughs is rather nebulous, so there is
lower confidence at pinpointing exact timing, location, and
magnitude of strong to severe storm potential early next week at
the moment.

Look for humidity and temperatures to increase towards the
middle of next week, with widespread upper 70s to mid 80s for
Tuesday and Wednesday along with widespread 60s to near 70F
dewpoints.

Late Next Week:

The prominent upper-level ridge may be suppressed slightly
farther south later next work week according to some mid-range
ensemble guidance and cluster analysis. This should keep the
hottest conditions south of the Northland, but upper 70s to mid
80s high temperatures and higher humidity should largely
persist. Additional shower and thunderstorm chances continue at
times for the second half of next week as periodic mid/upper-
level shortwave troughs continue to move through the northern
CONUS.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1241 PM CDT Fri Jul 18 2025

Widespread showers with a few embedded storms over north-central
and northeast Minnesota this afternoon will spread southeast
across the area this evening into tonight before exiting west to
east early to mid Saturday morning. Ceilings will be VFR for
most terminals until the evening, through some periodic MVFR
ceilings and visibilities in the rain/few embedded storms cannot
be ruled out. Ceilings and visibilities decrease even more this
evening into early Saturday morning, with widespread LIFR
conditions for most terminals still expected for areas south of
INL. Conditions should improve mid to late Saturday morning as
clouds scatter out from north to south, but Canadian wildfire
smoke is poised to move into the Northland starting Saturday
afternoon, which should lead to reduced visibilities spreading
in from north to south near or just after the end of the current
TAF period.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 245 PM CDT Fri Jul 18 2025

Generally light winds today, with some northeast winds of 5 to
15 knots this evening into early Saturday morning along with 1-2
foot waves. Winds then remain light and variable into Sunday
morning before turning northeasterly again with winds of 5-15
knots Sunday afternoon and evening, strongest in the southwest
arm of Lake Superior.

Rain showers with embedded isolated thunderstorms persist off
and on into tonight. No severe thunderstorms are expected,
though there may occasionally be locally gusty winds and cloud-
to-water lightning. Some reduced visibilities with and behind
the rain in fog also develop later this evening into early
Saturday morning. Additional chances for thunderstorms return
early next week.

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...Rothstein
AVIATION...Rothstein
MARINE...Rothstein