322
FXUS63 KDLH 172327
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
627 PM CDT Tue Jun 17 2025

.KEY MESSAGES...

- Multiple chances for thunderstorms Thursday through the
  weekend and into early next week.

- Severe thunderstorms are possible Thursday, Friday evening
  into early Saturday morning, and again late Sunday into
  Monday. Details in the exact timing and threats have low
  predictability at this time.

- Increasing heat and humidity across northeast Minnesota and
  northwest Wisconsin this weekend.

&&

.DISCUSSION...
Issued at 229 PM CDT Tue Jun 17 2025

After quiet weather on Wednesday, the pattern will become much
more active again for potentially severe thunderstorms Thursday
into the weekend. With this threat for severe thunderstorms,
increasing and potentially dangerous heat and humidity is
expected this weekend.

On Thursday, impulses embedded in 40-50 kts of northwest flow
aloft will propagate across the Northland Thursday afternoon
and evening. Buoyancy is expected to be greatest from the Leech
Lake and Brainerd Lakes areas, east into the I-35 corridor and
northwest Wisconsin on the order of 1500-2000 k/jg of MLCAPE.
With long hodographs, there will be the potential for supercells
with large hail being the primary threat. A lake breeze is
expected to diminish buoyancy and the severe threat near Lake
Superior.

Thereafter, a strong upper level ridge will build across the
central US Friday into Saturday, slowly shifting to east Sunday
into early next week. Global ensembles build this ridge to the
very top of the climatology for its heights Sunday into Monday
as a heat dome builds across the central and into the eastern
US. Moisture and warm air advection in long duration southerly
low level flow beneath the ridge this weekend into early next
week will increase heat, humidity and buoyancy levels across
northeast Minnesota and northwest Wisconsin. As a warm front
moves north late Friday into early Saturday, the CAPE and Shear
parameter space will be highly favorable for severe
thunderstorms aided by a strong low level jet, multiple mid
level impulses embedded in the building ridge and a plume of
high precipitable water and steep mid level lapse rates. High
temperatures on Saturday will climb into the upper 80s to the lower
90s, decreasing to the upper 70s to the upper 60s immediately
near Lake Superior with a lake breeze expected with low pressure
to the west of the lake.

The Northland is expected to be south of the warm front on
Sunday, solidly in the very strong warm sector with 850mb
temperatures near the top of the climatology and ECE EFI- SOT
signals favoring anomalous warm temperatures. Widespread high
temperatures in the upper 80s to the mid 90s are forecast on
Sunday with high humidity values. These high temperatures are
not only a concern, but, also the minimal cooling Saturday night
and potentially Sunday night which only increase the overall
Heat Risk. Sunday will be monitored for potential Heat
Advisories.

Late Sunday and into Monday as a cold front propagates across
the Northland with increasing southwest flow aloft, severe
thunderstorms will once again be a concern with significant
buoyancy and moisture in place. Capping could be a challenge
given the strength of the warm sector, however, this is just one
of many details that will have to be sorted out later this week
and into the weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 621 PM CDT Tue Jun 17 2025

Scattered storms are moving through the Northland for this
evening, which should end in the next couple hours. These storms
will mainly create heavy rain, which will lead to IFR
visibilities. There is a chance for fog tonight, especially in
areas where rain has fallen. HYR currently has the greatest
probability for fog, but BRD and DLH may also develop fog as
well.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 229 PM CDT Tue Jun 17 2025

Southwest winds at 10 to 15 kts this afternoon decreasing to
around 5 kts tonight. Fog is expected to develop late tonight
and into Wednesday morning. Light winds continue on Wednesday
with waves of less than 1 foot. On Thursday, northeast winds
increase to 10 to 15 kts.

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...PA
AVIATION...KML
MARINE...PA