Severe Thunderstorm Warning 2, NWS Duluth, MN

Area Forecast Discussion
National Weather Service Duluth MN
114 PM CDT Fri Apr 17 2026

.KEY MESSAGES...

- There is a chance of several severe thunderstorms through
  early evening east of a line from near Brainerd to McGregor to
  Duluth in Minnesota and over all of northwest Wisconsin.
  Risks include large hail, gusty winds, and tornadoes. Storm
  chances decrease from west to east through the afternoon.

- Scattered showers and non-severe storms are forecast over the
  remainder of the Northland through this afternoon.

- Colder into the weekend with breezy northwest winds. Some
  snowflakes are possible along the International Border
  Saturday afternoon.

- Warmer temperatures return next week with some near-critical
  fire weather possible Sunday - Tuesday.

&&

.UPDATE...
Issued at 115 PM CDT Fri Apr 17 2026

Thunderstorm coverage and intensity will increase east of a
Brainerd to Hibbing line this afternoon. A cold front stretched
from near Ely to Cloquet to the eastern Twin Cities per surface
observations and radar fineline returns. SPC 17Z RAP
mesoanalysis reveals a plume of 500-1000 J/kg of MUCAPE nosing
into southern Itasca County. The plume of MLCAPE of 500-2000
J/kg was farther east from eastern Pine County south to the Iowa
border. GOES-East band 13 clean window IR imagery features
warming cloud tops over southwest into east-central Minnesota
(with the exception of thunderstorms) which suggests large scale
subsidence. The storms over Crow Wing, Aitkin, western Carlton,
and southwest St. Louis counties and those farther upstream to
the northwest of the Twin Cites Metro appear to be the strongest
updrafts and may benefit from the suppressive effects of the
subsidence. East of the cold front over northwest Wisconsin a
small cluster of strong storms was located near Spooner as of 1
PM. Skies were clearing over northwest Wisconsin except around
and downstream of the storm cluster.

The subsidence and clearing skies will support a trend toward
stronger storms through this afternoon. The severe weather risk
will be maximized east of the cold front over northwest
Wisconsin where all types of severe weather remain possible.
West of the front, hail will be the main risk. Recent storm
reports indicate the short storms near and east of Brainerd were
producing large amounts of small hail. Freezing levels behind
the cold front were quite low quickly descending from around
9kft along the I-35 corridor to a few hundred feet west of
Brainerd.

&&

.UPDATE...
Issued at 1026 AM CDT Fri Apr 17 2026

A strong southerly 40-50 kt low-level jet was located over the
Minnesota/Wisconsin border into northwest Wisconsin late this
morning. Convergence and isentropic lift on the western
periphery of the jet will support thunderstorms, some strong to
severe, east of the surface cold front which stretched from just
east of Aitkin to just west of Hibbing to just east of Orr as
of 15Z. Rapid increase in Theta-E due to moisture advection and
diurnal warming led to a rapid expansion of MUCAPE northward
into central Minnesota and northwest Wisconsin. Expect these
trends to continue through the afternoon.

Within the past hour convection initiated over central MN and
the I-35 corridor and should persist as storms move quickly
north-northeast at 50-60 mph. While instability increased over
this area, the latest SPC RAP mesoanalysis reveals 250-750 J/kg
of MUCAPE where those storms were located. As instability
increases through early afternoon we anticipate storms to deepen
and the severe weather risk to increase. Hail is the most
likely threat at this time. Early convective development will
complicate the MLCAPE situation for this afternoon over
northwest Wisconsin. If storms remain elevated, the risk of
damaging wings will increase and the potential for tornadoes
will be small. If storms can become rooted near the surface, the
risk of tornadoes and hail would remain the greatest concern.
Subsidence in the wake of this early convection may erode the
cloud cover and provide several hours of surface heating by mid-
afternoon. Therefore the risk for all convective hazards
remains unchanged.

&&

.DISCUSSION...
Issued at 320 AM CDT Fri Apr 17 2026

A longwave trough is digging its way east early this morning
over the Plains, creating several areas of surface low pressure
from northern Minnesota to the Central Plains, with an attending
cold front connecting between them and pushing west to east.
That front, analyzed right along the edge of our western CWA
border early this morning, will be the feature to follow today.
Temperatures are still in the 50s and 60s in the warm sector
ahead of the front with a 50-55F dewpoint airmass expected to
advect north into the area through midday. We have a screaming
LLJ coincident with this front, with up to 65 knots at ~1.5km
off the deck from the KDLH VAD. We should see all these
ingredients come together as an unstable airmass stretching up
to Lake Superior this afternoon with plentiful shear to work
with.

As that more moist airmass noses up I-35 through this morning
we could see some areas of showers and thunderstorms begin to
develop across NE MN and up the MN-WI border in the 9am-1pm
timeframe. Through the afternoon, our cold front pushes east and
convection should grow upscale quickly from 1-5pm. This will
likely be the best window for potentially severe storms to
develop. If some discrete cells can develop (somewhat
conditional on how much morning precipitation there is and
where), brief supercellular structures are expected with all
hazards possible. Just ahead of the front surface winds could be
slightly more southeasterly which would increase hodograph
curvature favoring tornadic development. This environment will
likely be short-lived as the front will be progressive and
surface winds become more southwesterly nearer to the front (and
then NW once it passes). Discrete cellular convection will also
be more favorable for large hail up to golf bail size. As
convection grows upscale a more linear mode is favored with a
damaging wind threat. There is the potential that morning and
midday showers and thunderstorms could work to muddy the
atmosphere enough that any severe storms potentially stay to our
south. Should severe storms be able to develop, they should be
largely out of the area by 6-8pm.

Any thunderstorms could be capable of producing some locally
heavier rain up to 1"+. Flooding concerns are fairly minimal
with the progressive nature of this system, but extra water will
likely keep things wet in NW WI with high streamflows. Rain
over melting snow on the North Shore will also keep streamflows
high there.

A decent blast of CAA follows this system with winds turning
around to the NW Friday evening into Saturday. Guidance suggests
that these NW winds could get fairly breezy and strong along
the North Shore where gusts in excess of 30-45mph are possible.
Forecasts will need to be monitored here and a Wind Advisory may
be needed. Much cooler conditions this weekend will result in a
return to overnight lows below freezing and afternoon highs in
the 30s and 40s. Some light show showers are possible along the
International Border Saturday afternoon with little to no
accumulation expected.

Ridging returns next week, bringing temperatures back into the
40s, 50s, and 60s in the afternoon. Most global guidance doesn't
show our next widespread chance of precipitation until late
next week into the weekend. High pressure Sunday and Monday are
expected to lead to breezy winds and dry afternoons with minimum
RH of 25-30% or less. These days will need to be monitored for
possible near-critical fire weather concerns.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 115 PM CDT Fri Apr 17 2026

A low pressure system will move across the region this
afternoon and tonight. A cold front from near the Minnesota/
Wisconsin border to near KELO will propagate eastward this
afternoon and evening. HYR will start out with VFR conditions
descending to MVFR behind the front. Scattered showers and
thunderstorms will persist through early evening and will taper
off from west to east through tonight. Low stratus may loiter
behind the front for tonight. Winds will turn northwesterly
behind the front and will be gusty overnight and Saturday
morning. A few snow showers are possible Saturday afternoon and
evening after 18.18Z and could impact INL and HIB.

&&

.MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 320 AM CDT Fri Apr 17 2026

Winds become northwest through the afternoon and evening and
strengthen. Gusts of 20-35 knots are expected today into
Saturday evening. Small Craft Advisories have been issued except
for portions of the North Shore where a Gale Warning is in
effect. Gale force gusts are only expected for a brief period
this evening, after which a Small Craft Advisory will be needed
for those areas through Saturday. Thunderstorms are expected
Friday this and early evening which may bring gusty and erratic
winds, hail, and brief heavy downpours.

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

&&

.FIRE WEATHER...
Issued at 115 PM CDT Fri Apr 17 2026

A low pressure system and associated cold front will propagate
through the region this afternoon and tonight. Showers and
thunderstorms will gradually pass eastward through the
afternoon. A few severe storms are possible with large hail,
damaging winds, and a few tornadoes. The greatest severe weather
risk will be over northwest Wisconsin through this evening.
Precipitation may turn over to snow before ending over central
and north-central Minnesota. Saturday will feature strong and
gusty northwest winds. RH values will dip into the 30-35% range.
Temperatures begin to trend warmer on Sunday and closer to
normal on Monday. The warmer temperatures Monday and again on
Wednesday may pose a risk of near-critical fire weather
conditions due to low RH values and gusty winds.

See the Fire Weather Forecast product for a more thorough
breakdown of fire weather conditions.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...Small Craft Advisory from 4 PM this afternoon to 10 PM CDT
     Saturday for LSZ121-143>148.
     Gale Warning from 5 PM this afternoon to midnight CDT tonight
     for LSZ140>142.
     Small Craft Advisory from 4 PM this afternoon to 4 AM CDT
     Sunday for LSZ150.

&&

UPDATE...Huyck
DISCUSSION...Levens
AVIATION...Huyck
MARINE...Levens
FIRE WEATHER...Huyck

Hazardous Weather Outlook
National Weather Service Duluth MN
604 AM CDT Fri Apr 17 2026

MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-181115-
Koochiching-North St. Louis-Northern Cook/Northern Lake-
North Itasca-Central St. Louis-Southern Lake/North Shore-
Southern Cook/North Shore-North Cass-South Itasca-South Cass-
Crow Wing-Northern Aitkin-South Aitkin-Carlton/South St. Louis-
Pine-Douglas-Bayfield-Ashland-Iron-Burnett-Washburn-Sawyer-Price-
604 AM CDT Fri Apr 17 2026

This Hazardous Weather Outlook is for portions of northeast
Minnesota and northwest Wisconsin.

.DAY ONE...Today and Tonight

Scattered strong to severe thunderstorms are possible this afternoon
and evening. Large hail, damaging winds, and perhaps a tornado
are all possible hazards. The Storm Prediction Center has a Slight
Risk for much of northwest WI.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Near-critical fire weather conditions are possible for all or
portions of the Northland Saturday and again Monday due to
blustery winds and low relative humidity.

.SPOTTER INFORMATION STATEMENT...

Skywarn spotters may be needed this afternoon and evening, mainly
over northwest Wisconsin.

LSZ121-140>148-150-181115-
Bayfield to Oak Point WI-Grand Portage to Grand Marais MN-
Grand Marais to Taconite Harbor MN-
Taconite Harbor to Silver Bay Harbor MN-
Silver Bay Harbor to Two Harbors MN-Two Harbors to Duluth MN-
Duluth MN to Port Wing WI-Port Wing to Sand Island WI-
Sand Island to Bayfield WI-Oak Point to Saxon Harbor WI-
Outer Apostle Islands Beyond 5 NM from Mainland-
604 AM CDT Fri Apr 17 2026

This Hazardous Weather Outlook is for portions of Lake Superior
and the Nearshore waters of western Lake Superior.

.DAY ONE...Today and Tonight

Scattered thunderstorms are possible this afternoon and evening.
Some storms could be strong to severe.

Gusty northwesterly winds are forecast starting this evening and
overnight tonight. Gale Warnings and Small Craft Advisories have
been issued for late this afternoon and tonight.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Gusty northwesterly winds are likely Saturday and Saturday night.
Small Craft Advisories are in effect through Saturday night.

LE

More information may be obtained at the following web address:
http://www.weather.gov/duluth

Preliminary Local Storm Report
National Weather Service Duluth MN
244 PM CDT Fri Apr 17 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0235 PM     Hail             3 W South Range         46.59N 92.05W
04/17/2026  M0.50 Inch       Douglas            WI   Trained Spotter

            Largest hail measured was 0.6 inches in
            size. Hail was falling for 5 minutes.

&&

JJM

Preliminary Local Storm Report
National Weather Service Duluth MN
245 PM CDT Fri Apr 17 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0239 PM     Marine Hail      4 N South Range         46.67N 92.00W
04/17/2026  M1.00 Inch       Douglas            WI   Public

            Report from mPING.

&&

JJM