308
FXUS63 KDLH 022349
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
649 PM CDT Wed Jul 2 2025

.KEY MESSAGES...

- Isolated showers and storms this afternoon/evening. Isolated strong
  to severe storms are possible, with large hail and damaging
  wind being the main threats.

- Very warm and humid on July 4. Heat advisories may be needed.

- Strong to severe thunderstorms are possible during the afternoon/evening
  on July 4. Heavy rain could lead to some flash flooding
  concerns as well.

&&

.DISCUSSION...
Issued at 1245 PM CDT Wed Jul 2 2025

A surface and near-surface convergence boundary has been the
focus of passing showers and storms through the morning, and
this is going to be where any further convection this afternoon
and evening will be most likely to set up. This is coupled with
a weak passing trough aloft and a cold front that will be moving
south, but then becoming quasi-stationary this evening. This
boundary has been roughly oriented with US-2, and essentially
areas north of this area will likely not see too much convective
activity this afternoon/evening since there simply won`t be
enough instability. Along and south, we`ll see SBCAPE inching
into the 1-2 kJ/kg range along with some favorable shear around
30-40 kt this afternoon. It doesn`t look like low-level shear
will be favorable for rotation, but there could certainly be a
few storms that could produce some large hail or damaging winds.
The threats will probably be low-end severe owing to a lack of
broad synoptic forcing. Thunderstorm coverage is expected to be
isolated, but any storms that can get themselves going could be
a little feisty.

Going into Thursday, ridging aloft and high pressure at the surface
will lead to plenty of warm air advection, but also general
subsidence that should keep the weather warm, but generally quiet.
The possibility of a rogue shower or storm somewhere in the region
can`t be ruled out given potentially unstable air, but dry weather
is more likely.

Going into Independence Day, we`re looking at some pretty active
weather, with threats for hot temperatures and humid dew points,
strong to severe thunderstorm chances, and some flooding potential.
More details on each below.

Strong southerly warm air and moisture advection will bring some
very warm temperatures into the Northland. Most places have a 90%+
percent of seeing 80 degrees or warmer, with parts of the North
Shore being a possible exception. Probabilities for 85 degrees or
warmer are 50-70% especially south of the US-2 corridor. Highs
around or just above 90 can`t be ruled out either. Dew points
topping out around 70 will lead to wet bulb globe temperatures right
around 80, altogether leading to a moderate HeatRisk for much of the
Northland. Heat advisories may be needed. It will be especially
important to plan ahead for the holiday, ensuring that you and those
close to you have plenty of water and places to go to keep cool, as
this level of heat/humidity affects most individuals who are
sensitive to heat.

As for the storms, we`ll have a potent cold front setting up
somewhere around northwest Minnesota by the late afternoon. Areas
ahead of the front (our entire region) will see building
instability through the day (1-2+ kJ/kg MUCAPE). There will
likely be a shallow cap that will keep the instability bottled
up near the surface early, but the forcing near and a bit ahead
of the cold front should pretty efficiently erode that. There
will be a bit of a displacement in convection-favoring features
such that peak instability (afternoon and early evening) may
happen a bit before wind shear strengthens (evening), so the
window for potentially strong to severe storms may be a bit
narrow (but also roughly timed when many holiday festivities may
be happening in the ~5-11 PM timeframe). Right now, severe
threats are conditional based on how ingredients can match up
during and just after peak daytime heating. Therefore, SPC has a
marginal risk for severe weather across the region. Damaging
winds and large hail will be the main threats.

PWATs are expected to rise into the 1.5"-2.0" range come July 4. In
addition, shear is expected to orient itself pretty much parallel to
the cold frontal boundary. Since it is a cold front and should be
somewhat progressive, flooding risk will be somewhat mitigated. But,
such high moisture and potential for at least localized training of
storms could bring some localized flash flooding. WPC has most of
Minnesota in a marginal risk (<15% chance) for flash flooding,
mainly in northeast Minnesota.  There`s some concern that there
could be multiple waves of rain/storms as well, with the initial
round ahead of the front on July 4th during the afternoon/evening,
and then another round with the cold front passing through later in
the night into Saturday morning before ending. For most, flooding
probably will not be much of an issue, but there are some places
that may pick up 1-2" (or locally higher) of rain over several hours
that could lead to some localized issues.

After the cold front and storms pass through on Saturday, some
relatively cooler temperatures (highs in the 70s) are looking most
likely Sunday and into early next week. Periodic passing waves may
bring off-and-on chances for showers and thunderstorms.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 648 PM CDT Wed Jul 2 2025

Isolated to scattered showers and thunderstorms have developed
over northwest WI and eastern MN this afternoon, which may
affect KHYR, KDLH and possibly KBRD. Storms may produce some
gusty and erratic winds and MVFR/IFR conditions may be possible
due to heavy rain. Once these pass to the southeast, fog may be
a concern for overnight, most likely for KHYR. Have included
some MVFR visibilities for a few hours, with a brief period of
IFR conditions possible. Signals for fog are much less, if not
zero, at other terminals, so no fog has been added at this time.
Otherwise, expect VFR conditions through the period.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 244 PM CDT Wed Jul 2 2025

Expect west to southwest winds this afternoon, becoming light
and variable tonight before becoming northeasterly later tonight
and through Thursday. Expect speeds to increase to 10-15 kt and
gusts to 20 kt with waves to around 2 ft. There is a ~20% chance
that gusts could rise to around 25 kt, so we will keep a close
eye on potential need for a Small Craft Advisory around the Twin
Ports, but right now confidence isn`t high enough that one will
be needed.

Into July 4th, winds will shift more southerly with some gusts
up to 20 kt. Rain and thunderstorms are expected to arrive in
the late afternoon and evening hours. A few strong to severe
thunderstorms capable of wind gusts over 40 kt and large hail to
quarter size are possible.

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...JDS
AVIATION...LE
MARINE...JDS