310
FXUS63 KDLH 031727
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1227 PM CDT Thu Jul 3 2025

.KEY MESSAGES...

- Isolated strong to severe storms are possible late this
  evening into Friday morning, mainly for northwest Wisconsin
  and far north-central Minnesota. Localized damaging wind gusts
  and small to marginally severe hail are the main threats.

- Very warm and humid on July 4 (Friday). Heat Advisories have
  been issued.

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

&&

.DISCUSSION...
Issued at 401 AM CDT Thu Jul 3 2025

Today - Tonight:

At the surface, a cold front situated just south of the
Northland early this morning will push back north as a warm
front today into Friday. Aloft, the apex of an upper-level
ridge over the Northern Plains will slowly be working east into
the Northland later today into Friday. This will bring an
increase in both temperatures and moisture for today and
especially Friday. PWAT values in the 1.5-2" range overspread
the Northland this evening and tonight, with 2" being towards
the very top end of climatology for this time of year. Mid to
upper-level forcing for storms looks to be low or non-existent
most of the day as 500 mb heights will be increasing with the
approaching ridge axis. With that said, some very weak
mid/upper-level shortwave troughing/vorticity that rounds the
top of the ridge and moves through the Northland this evening
and tonight. This could be enough forcing to kick off isolated
storms along the warm front in east-central MN into northwest
WI, with a limited threat for a few strong to severe storms with
hail up to 1" in diameter and localized gusty/damaging winds
given MLCAPE values of 800-1800 J/kg.

An additional area of showers/storms are possible for far
north-central Minnesota tonight as an MCS from North Dakota
tracks east. There is still some uncertainty on how long it
holds together as it tracks into northern portions of Minnesota
as surface-based inhibition should increase with eastward
extent. If these storms can hold on long enough, localized
damaging wind gusts up to 60 mph couldn`t be ruled out mainly
along and north of a Walker to Hibbing to Ely line.

Outside of storms, today will also see warmer temperatures and
heat indices. Widespread highs and heat indices in the 80s are
expected away from Lake Superior and the head of the Lake, with
cooler temperatures near Lake Superior. Onshore winds at the
head of the Lake around 10-15 mph with gusts to 20-25 mph are
expected to lead to a high risk for rip currents today through
this evening at Minnesota Park Point and Wisconsin Point
beaches. A Beach Hazard Statement has been issued for this rip
current threat.

Friday - This Weekend:

Several impactful weather concerns for the Friday/Saturday timeframe:

1) Heat and humidity for Friday, 2) Strong to severe
thunderstorm potential Friday and Saturday afternoons/evenings,
and 3) Heavy rainfall and flooding potential Friday evening into
Saturday.

Independence Day (Friday) has seen a continued slight upward
trend in the temperature and dewpoint forecast as the apex of
the upper-level ridge slides overhead. Remnants of the overnight
showers storms in northern MN and northwest WI will be sliding
east of the area by late morning, which may complicate the high
temperature forecast a bit depending on the duration of
lingering cloud cover, though strong warm air and moisture
advection should still offset this a bit. Widespread dewpoints
in the upper 60s to low 70s and high temperatures away from Lake
Superior in the upper 80s to locally mid 90s are expected,
though high temperatures in the 70s to mid 80s from the Twin
Ports up the North Shore near Lake Superior are expected due to
winds off the Lake. This will lead to widespread heat indices in
the low to upper 90s away from Lake Superior, and maybe even
some pockets of 100F heat indices. Heat Risk values will also be
widespread Moderate values (heat affects most individuals
sensitive to heat) to some pockets of Major values (heat affects
anyone without effective cooling or adequate hydration). A Heat
Advisory has been issued for all of the Northland aside from
the North Shore for late Friday morning through mid evening.
Because of this oppressive heat and humidity is occurring on
Independence Day when outdoor events will be more common, it
will be particularly important to plan ahead and ensure that you
and those close to you have plenty of water and places to go to
keep cool.

Regarding precipitation/storm potential, scattered shower and
thunderstorm development and potential isolated strong to
severe storms return as early as later this afternoon into
tonight. A low pressure system approaching from the Northern
Plains/Canadian Prairies on Friday should put most of the
Northland solidly in the warm sector of the low pressure. A
capping inversion should hold across most of the area as the
better synoptic forcing for ascent remains moreso over the
Dakotas. By late Friday afternoon/early evening, the cold
front/surface trough should be situated from central South
Dakota northeast towards International Falls as falling heights
aloft and low level convergence begins to initiate storms along
and just ahead of the front. Storms should then slowly spread
southeast during the remainder of the evening into overnight
hours mainly in central to northeastern MN on a more widespread
basis. Some of these storms should be strong to severe on a more
widely scattered basis with 0-6km bulk shear values of 30-35 kt
and 1500-3000 J/kg of MUCAPE to initially work with, though
instability does drop off with time later in the evening and
overnight and storm mode becomes a more messy cluster rather
quickly. The primary hazard would be damaging wind gusts given
plenty of downdraft CAPE, with large hail as a secondary threat,
particularly initially in the late afternoon/early evening when
storms have yet to congeal before the hail threat quickly
decreases. There is also a period of time late afternoon into
the late evening where storms could be surface based and have
just enough low-level helicity for a non-zero tornado threat
(2%, the lowest SPC Convective Outlook threshold for tornado
mention) across far northern Minnesota near the front. This
tornado threat remains very limited at best.

A deep layer of southwest winds aloft being parallel to the
surface cold front would point to a heavy rain and at the very
least a localized flash flooding potential Friday evening into
Saturday. PWATs increase to around 2" and the surface to
freezing level depth being around 13-15,000 feet will create a threat
for training storms to produce efficient, heavy rainfall rates
with multiple waves of thunderstorms from the afternoon/evening
storms and then continued thunderstorms as the cold front
actually slides through the Northland overnight into Saturday
morning. It still doesn`t look like flooding would be an issue
for most locations, but some portions of the Brainerd Lakes into
the Iron Range and Arrowhead would be favored the most for 1-2"
of rainfall, with potential localized amounts of 2"+ (25-35%
chance in the Iron Range) for Friday through Saturday. Rainfall
probabilities drop off with southeastward extent into the Twin
Ports and northwest WI. Probabilities of >1" of rainfall in the
Twin Ports are around 50-60% and taper off to 20-40% in
northwest WI through Saturday.

As the cold front continues trekking southeast through the
Northland on Saturday, with noticeably less hot temperatures
with highs in the upper 70s to low 80s. There remains a short
window of time Saturday afternoon and evening where a few strong
to severe storms will be possible once again, primarily in
northwest WI along and ahead of the cold front depending on how
cloud cover and lingering precipitation from overnight storms
impacts instability.

Largely cooler and drier for Sunday behind the cold front with
highs in the 70s and more comfortable dewpoints in the 50s to
around 60.

Early Next Week:

Zonal mid to upper-level flow for early next week turning
northwesterly for mid-week. It looks like there will be periodic
shortwaves moving through this flow pattern aloft, which should
bring additional shower and thunderstorm chances at times with
seasonal high temperatures. There doesn`t appear to be any
strong signal at this time for strong to severe storm potential
early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1226 PM CDT Thu Jul 3 2025

VFR conditions to start the forecast period. Satellite and
radar show and area of showers moving across ND that may enter
into the Brainerd Lakes region this evening. Overnight, CAMs
are suggesting a line of showers and storms developing along a
warm frontal boundary. This line look to set up through NW WI
and to INL and moves east through the morning.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 401 AM CDT Thu Jul 3 2025

Northeast winds increase to 10-15 kt and gusts to 20-25 kt with
waves to around 2-3 ft in the southwest arm of Lake Superior
today, mainly this afternoon and evening. A Small Craft
Advisory has been issued. Some showers and storms are possible
tonight into Friday morning, but strong to severe storms are not
expected.

On July 4th, winds will shift more southerly with some gusts up
to 20 kt mainly near the Twin Ports. Rain and thunderstorms are
expected to arrive in the evening hours Friday and through
Saturday. A few strong to severe thunderstorms capable of wind
gusts over 40 kt are possible, mainly Friday evening/early
overnight, but also potentially Saturday afternoon and evening.
Otherwise, non-thunderstorm winds on Saturday veer from
southwesterly to westerly with gusts around 15 kt.

For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Heat Advisory from 11 AM to 8 PM CDT Friday for MNZ010>012-018-
     019-025-026-033>038.
     Beach Hazards Statement until 10 PM CDT this evening for
     MNZ037.
WI...Heat Advisory from 11 AM to 8 PM CDT Friday for WIZ001>004-
     006>009.
     Beach Hazards Statement until 10 PM CDT this evening for
     WIZ001.
MARINE...Small Craft Advisory until 10 PM CDT this evening for
     LSZ143>146.

&&

$$

DISCUSSION...Rothstein
AVIATION...Britt
MARINE...Rothstein