037
FXUS63 KDLH 160622
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
122 AM CDT Sat Aug 16 2025

.KEY MESSAGES...

- Strong to severe thunderstorms may be possible this evening,
  but the potential is decreasing. Large hail and damaging winds
  are the concerns with any severe storms that develop.

- A second round of strong to severe thunderstorms will be
  possible Saturday morning with damaging winds being the
  primary concern.

- Additional shower and thunderstorm chances linger through the
  weekend into Monday. High pressure and drier conditions return
  from Tuesday into Thursday morning.

&&

.DISCUSSION...
Issued at 324 PM CDT Fri Aug 15 2025

A cold front associated with vertically-stacked low pressure near
Hudson Bay has stalled along the Iron Range as of this afternoon.
With this now stationary front draped across portions of the CWA,
conditions have been widely variable. Mostly sunny skies have been
observed north of the Iron Range with more comfortable dewpoint
temps, while the remainder of the CWA has seen mostly cloudy skies
and sticky dewpoints in the 70s. In addition to humid conditions,
areas south of the stationary front have seen scattered showers and
thunderstorms early this afternoon.

The main concern today into tomorrow morning will be the potential
for strong to severe thunderstorms. The aforementioned dewpoints in
the 70s across the southern half of the CWA, when combined with
moderately steep mid-level lapse rates of 7-8 degC/km, will increase
MUCAPE this evening to 2000-2200 J/kg. This high instability will be
combined with favorable 0-6km bulk shear around 40 knots. While
these convective parameters are favorable, the amount of capping
present and an overall lack of strong lift will be the primary
limiting factors for severe potential this evening. Recent runs of
CAMs reflect this capped and weakly forced environment, with
numerous models showing limited thunderstorm development this
evening. However, given the favorable thermodynamic and shear
environment this evening, any developing towers will need to be
monitored for rapid growth over northwest WI. Potential hazards
include large hail to 1.5" and damaging wind gusts to 60 mph.

On Saturday morning, strong to severe thunderstorms will be possible
once again as a MCS develops over the central Plains and moves into
the CWA along with a 500mb shortwave trough. MUCAPE will remain very
favorable in excess of 2000 J/kg late tonight into Saturday morning.
Model soundings suggest that much of this instability will
remain elevated, but a 25-30 knot LLJ will help maintain the
strength of this MCS as it moves into the CWA. There is some
timing and location discrepancies still in the CAMs, but the
overall trend is that a line of thunderstorms will move through
the upper Midwest on Saturday morning. Given the likely storm
mode, damaging winds up to 70 mph will be primary concern.
However, uncertainty is high regarding whether or not these
strong winds reach the surface as storms may still be elevated
due to nocturnal cooling.

After the convection exits the CWA early Saturday afternoon, there
will likely be a brief lull in precipitation that will continue into
Saturday night. On Sunday, a shortwave moving into the north-central
CONUS will bring additional chances for showers and thunderstorms
through the day. This shortwave will also tighten the pressure
gradient across the region, leading to a chance for gales over Lake
Superior and overall cooler temps as marine air is advected inland.
High temps on Sunday will be noticeable cooler in the mid 60s to low
70s. The shortwave bringing precip chances on Sunday will linger
into Monday.

Rain chances finally exit the area on Monday night into early
Tuesday morning, ushering in a period of high pressure around mid
next week. Expect pleasant summer weather from Tuesday through
Thursday morning with partly to mostly sunny skies and high temps in
the 70s to low 80s. The next chance for showers and storms won`t
arrive until late Thursday into Friday morning.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1244 AM CDT Sat Aug 16 2025

Watching scattered showers fill in across northwest Minnesota
this morning, but expect coverage to remain scattered. With
that, might need to make amendments for INL, HIB, and DLH for
VCSH or VCTS.

A cold front stretches across the area, currently located along
the North Shore to DLH to BRD, with northerly wind components
now noted at those terminals. MVFR clouds lingering near the
front will allow for occasional cig drops at DLH and BRD.
Further south where moisture is higher, a mix of cig heights and
vis drops are expected at HYR.

A more robust line of rain and thunderstorms is expected to move
in from the southwest and affect most terminals except INL
Saturday morning until around midday. MVFR and brief IFR
conditions will be possible along with gusty winds and perhaps
some small hail. Conditions are expected to improve to VFR
everywhere Saturday afternoon as drier air moves into the
region.


&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 324 PM CDT Fri Aug 15 2025

Showers and thunderstorms will continue to be possible this
afternoon and evening as a cold front remains stalled over the
Iron Range. Shower and thunderstorms remain in the forecast
through Saturday, with a few strong storms possible on Saturday
morning. Gusty thunderstorm winds in excess of 34 knots and
frequent cloud to water lightning are the primary concerns.

Starting Saturday night, a tightening pressure gradient is expected
to increase northeast winds across western Lake Superior. On Sunday,
gale-force wind gusts are appearing increasingly likely (50-60%
chance) for portions of western Lake Superior. Given this rare
potential, a Gale Watch has been issued for all of western Lake
Superior from late Sunday morning into Sunday evening. In addition
to gales of 35 knots, waves of 3-7 feet will also be possible,
especially along the North Shore. Small Craft Advisories are in
effect ahead of this potential for gales. Keep an eye out for any
potential upgrades to a Gale Warning heading into this weekend.

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 from 10 PM this evening to 10 AM CDT
     Sunday for LSZ121-140>148-150.
     Gale Watch from Sunday morning through Sunday evening for
     LSZ121-140>148-150.

&&

$$

DISCUSSION...Unruh
AVIATION...HA
MARINE...Unruh