568
FXUS63 KDLH 300836
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
336 AM CDT Mon Jun 30 2025

.KEY MESSAGES...

- Widely scattered general thunderstorms are expected today and
  Wednesday across all of the Northland.

- Very warm and muggy conditions are expected Friday.

- Friday PM and Saturday, the next chances for more widespread
  strong thunderstorms set up. A few of these strong storms may
  be severe.


&&

.DISCUSSION...
Issued at 230 AM CDT Mon Jun 30 2025

An area of scattered showers and isolated thunderstorms moves
through the Brainerd Lakes to east-central MN to inland
northwest Wisconsin this morning. The primary hazard would be
cloud-to-ground lightning from the isolated thunderstorms. These
chances quickly decrease by mid-morning today though as a
boundary drops southeastward first entering north- central
Minnesota late morning today. Behind the boundary, widely
scattered general thunderstorms form along and north of the Iron
Range by mid-day and spread southeastward into eastern Minnesota
by early afternoon as northwest Wisconsin storms pop up as well.
Expect the primary hazards this afternoon and early evening to
be cloud-to-ground lightning strikes and up to half-inch of
rainfall, and erratic outflow wind gusts to 40 mph. An isolated
storm strengthening to produce small hail cannot be ruled out,
but is more favored for inland northwest and north-central
Wisconsin where slightly better shear profiles align with the
modest CAPE that is available areawide. The diurnal heating
component to these storms allows chances for precipitation to
quickly decrease by late evening hours today, lingering last in
north-central Wisconsin and the Arrowhead as the mid-level
trough pulls well east of the region.

A drier airmass and trailing mid-level subsidence on Tuesday
creates a downturn in shower and storm chances outside of the
Arrowhead. Medium range global model guidance progs a vorticity
maxima dropping southeastward through far northern Ontario. The
associated moisture influx into the Arrowhead and that weak
forcing could be just enough to overcome the mid-level cap for
areas of eastern St. Louis County and through the entire
Arrowhead for isolated general thunderstorm development. Any
shift north or further east of the vort max and/or decrease in
available moisture though likely quickly decreases the already
low isolated storm chances though for Tuesday afternoon.

Along and south of the Iron Range starting Wednesday morning,
the second more widespread chances of general thunderstorms
build back of the region. The most moist airmass is likely along
and south of US Hwy 2, which coincides with available modest
amounts of CAPE from Wednesday late morning to afternoon. This
will again be a shear-limiting day with up to 35 knots of bulk
shear progged for the Brainerd Lakes to all of northwest
Wisconsin. So expect the best chances of general thunderstorms,
a few strong in far eastern Minnesota and across northwest
Wisconsin, Wednesday mid-day to late afternoon and little to no
activity in the Borderlands.

After a quiet Thursday, convection is likely to initiate in the
Dakotas on the tip of a low-level southerly jet. As a warm front
lifts through Minnesota and western Wisconsin Thursday night,
the Dakota`s convection will be a large factor in just how
unstable of an atmosphere can be available for possible
convection in the Northland Friday afternoon to early overnight.
If storms are able to initiate Friday PM, the other limiting
factor on how organized anything would be is the lower-end
shear profiles depicted by multiple medium-range global
deterministic models. Even with the abundance of CAPE and very
moist atmosphere (precipitable water progged from 1.5 to 2
inches), current thinking would lean towards more disorganized
clusters of strong to locally severe storms Friday. With the
timing of this late week warm front, a very warm and humid
Independence Day is likely for all areas. Forecast air
temperatures right now range in the mid to upper-80s, but with
the dewpoints in the upper-60s, heat index values approach the
mid-90s. This day will have to be continually assessed for
possible heat-related headline needs, especially along and south
of US Hwy 2 in Minnesota and across northwest Wisconsin.

After the July 4th storm and heat hazard potential, lingering
storm chances Saturday will have to be monitored for strength,
especially east-central Minnesota and northwest Wisconsin as
the cold front aloft still moves through northeast Minnesota.



&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1213 AM CDT Mon Jun 30 2025

Will have to watch for areas of fog tonight forming tonight in
inland northern Wisconsin which may locally reduce visibilities
down to IFR conditions; Hayward TAF amendments may also be
needed if it sets up at that terminal from 08-12Z this morning.
Diurnal cumulus form late this morning regionwide as a broad
swath of general thunderstorms are likely today from 18-23Z;
have maintained PROB30s at all terminals for this likely
scenario as a result. An upgrade to either TEMPOs or prevailing
thunderstorm mentions may be needed though in subsequent TAF
issuances.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 204 AM CDT Mon Jun 30 2025

West to southwest winds prevail the next few days, all around or
under 20 knots. These conditions keep wave heights forecast up
to 2 feet mainly along the North Shore, lesser into the Twin
Ports and along the South Shore. Expect a wind shift Thursday to
easterly. Today and Wednesday are both expected to see nearshore
waters thunderstorm chances.

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...NLy
AVIATION...NLy
MARINE...NLy