423
FXUS63 KDLH 160748
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
248 AM CDT Mon Jun 16 2025

.KEY MESSAGES...

- A conditional threat for strong to severe thunderstorm
  chances for this afternoon and evening.

- Tuesday onward, occasional rain chances, especially later this
  week into the weekend.

- Seasonably warm temperatures through the week. Some warm to
  hot temperatures in the 80s possible next weekend.

&&

.DISCUSSION...
Issued at 236 AM CDT Mon Jun 16 2025

The primary forecast concern remains the potential for severe
thunderstorms later this afternoon and into the evening hours.
Model guidance has come into better agreement, but significant
uncertainties persist, particularly regarding the role of
prevalent low level clouds, an inversion, and the impact of
local-scale features.

A subtle shortwave trough will glide through the Upper Midwest,
with an associated surface cold front scheduled to sweep across
the region this evening. Ahead of this system, morning showers
and some elevated, non-severe thunderstorms will move through
parts of the Northland. This initial round of convection, while
spotty, has likely reinforced a capping inversion in the lower
atmosphere. The strength and persistence of this cap is the
primary source of uncertainty for the afternoon forecast. If the
cap holds strong, it could suppress or delay widespread
thunderstorm development. Furthermore, the stable lake layer
will act as a local check on instability for communities
immediately adjacent to the lake.

Despite these limiting factors, a plume of very warm and moist
air, with surface dewpoints climbing into the upper 60s, will
surge northward. MLCAPE values potentially reaching 1500-2500
J/kg will brush the southern portion of our forecast area. Mid-
level lapse rates are steepening to 7-8 C/km, contributing to a
strong to severe storm thermodynamic environment.

The kinematic setup is also impressive. Moderate to strong
deep-layer shear (40-50 kts) and favorably veering low-level
winds will support organized convection, including the potential
for discrete supercells if clouds manage to clear which I think
is unlikely. However, if they do clear, the initial storm mode
will likely be individual supercells, posing a threat of very
large hail (potentially 2 inches or more in diameter) and
tornadoes. The greatest threat for this activity remains across
our southern counties, from the Brainerd Lakes to Hinckley and
into northwest Wisconsin, where the instability and shear are
expected to be most pronounced. This area aligns with the SPCs
Enhanced Risk (level 3 of 5) for severe thunderstorms. As the
evening progresses, these discrete cells may merge into a line
or clusters, with the primary threat transitioning to damaging
winds though I think by this time lack of CAPE will be a
limiting factor.

For areas farther north, including the Iron Range and the North
Shore, the severe threat is more conditional and expected to be
lower due to the stabilizing influence of the lake and less
robust instability. However, any storms that can become
established in this region could still produce hail and strong
wind gusts.

We will continue to monitor satellite and radar trends closely.
Any sustained breaks in the cloud cover could lead to a rapid
increase in the severe weather threat. Stay weather aware this
afternoon and evening.

The cold front will exit the region late tonight, ushering in a
much quieter pattern for Tuesday. Northwest flow will bring
drier and slightly cooler air into the region. Expect mostly
sunny skies with some diurnal cumulus development.

The extended forecast period looks to be relatively quiet and
pleasant though isolated diurnal non-severe thunderstorms will
likely be a threat most days. An upper-level ridge will build
over the region, leading to generally dry conditions and a
warming trend through the end of the week. High temperatures
will be in the 70s on Wednesday and climb into the 80s for many
locations by the weekend while cooler by the lake will be an
ongoing theme.

The weekend appears to be warm, but there are some hints that
it could be stormy as a strong LLJ inches into the Northland.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1228 AM CDT Mon Jun 16 2025

A messy TAF period with IFR seeping in this morning. Rounds of
convection are possible throughout the TAF period after about
09Z. Hard to pinpoint timing with several flavors of solutions
in the guidance. The best surge in tsra activity will be between
19 and 04Z. Low stratus and fog follows the tsra tonight. Winds
fairly light though will increase in intensity this afternoon
and switch from south to more west after the cold front passes.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 236 AM CDT Mon Jun 16 2025

East winds today ahead of an approaching low pressure system,
remaining in the 10 to 15 knot range for speeds. Waves will
remain in the 1 to 2 foot range. A cold front will move through
the area this evening, causing winds to veer to the west tonight
into Tuesday. Wind speeds may bump up to around 15 knots for a
few hours this evening before diminishing again to 10 to 15
knots. Waves should remain in the 1 to 2 foot range through
Tuesday. A line (or two) of thunderstorms is expected to impact
the waters this afternoon/evening.

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...Wolfe
AVIATION...Wolfe
MARINE...Wolfe