Severe Thunderstorm Warning 9, NWS Duluth, MN

Area Forecast Discussion
National Weather Service Duluth MN
256 PM CDT Mon Jul 3 2023

.DISCUSSION...(This evening through Sunday)
Issued at 255 PM CDT Mon Jul 3 2023

Key Messages:

1. Shower and storms are firing off a cold front moving across the
region this afternoon. A few storms have been strong to severe.

2. Showers taper off tonight but another round is expected to enter
from the west tomorrow morning.

3. Scattered showers and storms are expected throughout Independence
Day. Some storms may turn severe in the afternoon and evening hours.

4. Heavy rain may also occur if storms track over the same areas.
With NW WI likely seeing the best chances for increased
precipitation.

5. Cooler temperatures return Wednesday as a secondary cold front
ushers the remaining showers out of the region.

Current Conditions - Independence Day:

A cold front was draped across northern MN this afternoon extending
from northern Lake county and swinging southwest into the Pine
county. Satellite/radar has shown convection firing off along the
boundary. Temps have climbed into 80s with dewpoints in the upper
60s out ahead of the front. With quite a juicy atmosphere on tap we
are still slated for a marginal risk of severe weather this
afternoon for much of the Northland. The exception to this will be
locations that have already been passed by aforementioned cold
front. Models are producing high instability with a few in excess of
2500 J/Kg. The limiting factor is the amount of bulk shear we have
to work with. Optimal shear will not coincide with the best
instability today with the favorable values trailing behind the
front in the more stable air. However, the explosiveness of the
instability in play paired with 15-20 kts available could still lead
to rapid storm growth and primarily large hail and damaging winds.
The latest outlook from SPC has removed the marginal threat from
Koochiching south to Cass county due to the progression of the cold
front while the rest of the region remains highlighted. Once an area
experiences the frontal passage the potential for any storm
redevelopment drastically reduces.

Overnight convection is expected to taper off as the boundary stalls
out of the Northland. Aloft we will see cyclonic flow as troughing
moves across the Northern Plains. By Tuesday morning the right
entrance region of an upper level jet will be entering central MN.
The increased divergence aloft combined with the stalled out
boundary and baroclinic zone will likely increase precipitation
chances across our western counties. Through the day, diurnal
heating will cause destabilization once again across a large swath of
the region. There is also signs of some vorticity couplets rotating
through in the afternoon hours promoting additional lift. However,
due to the potential of the morning showers and storms traversing
the region that leaves a high amount of uncertainty with how the
afternoon will play out. If the morning showers are widespread
enough this will cut back on the overall instability able for the
environment to recover. The instability that does manage to grab a
foothold will have a more favorable shear environment than the
previous day with speeds closer to 30-35 kts. This will once again
allow for damaging winds and large hail to develop. For now, SPC the
Brainerd Lakes up into the Arrowhead and east through NW WI
highlighted in a slight risk for severe weather.

Heavy Rain Potential:

In addition to the the severe storm threat we will also be
monitoring the chance for excessive rainfall. As it stands WPC has
the Northland highlighted in a marginal risk today through Wednesday
with the threat shifting east with time. Areas that see repeat
thunderstorms will be at risk for flash flooding. The latest trends
still favor NW WI having the lions share of the moisture through
Wednesday. Although, the overall totals have scaled back some from
the previous forecast.

Wednesday - End of the Week

A secondary cold front dropping out of the Canadian Prairies will
sweep across the Northland on Wednesday ushering out the remainder
of the showers and storms lingering over the region. Behind this
front we will be able to enjoy some cooler temperatures with upper
60s expected across northern MN and mid to low 70s for NW WI
Wednesday. High pressure will settle in for Thursday as things
gradually warm back into the low 70s. The current suite of 12Z
deterministic guidance is keeping high pressure and quiet weather
through the late week. Another cold front is projected to drop out
of the Canadian Prairies late Friday and into the weekend but this
far out model discrepancies remains rather high.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1226 PM CDT Mon Jul 3 2023

A cold front is marching across the Northland this afternoon and is
delineated well with the MVFR stratus deck moving across northern MN.
This front could bring strong to severe thunderstorms to DLH/HYR
this afternoon and evening. Showers and storms will taper off
overnight with some fog potential in HYR and possibly DLH. Another
round of rain and thunderstorms will enter from the west tomorrow
morning impacting BRD/INL initially. Additional showers and strong to
severe storms will be possible again tomorrow afternoon and
evening.

&&

.MARINE...
Issued at 255 PM CDT Mon Jul 3 2023

A cold front is advancing southeast across the region this afternoon
with showers and storms firing off the boundary. Some storms have
been strong to severe. This potential will continue into the evening
hours before tapering off. Expect winds to switch to out of the
northwest behind the front. Additional chances for showers and
storms will return tomorrow afternoon. There will once again be the
potential for strong to severe storms. By Wednesday a secondary cold
front will usher the remaining showers and storms out of the region
with increasing winds upwards of 10-15 kts out of the Northwest.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  60  80  57  71 /  20  50  60  20
INL  54  75  50  65 /  10  40  20  20
BRD  61  80  54  70 /  40  60  50  10
HYR  60  88  58  75 /  50  70  80  40
ASX  58  84  59  73 /  50  60  70  40

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

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

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Special Weather Statement
National Weather Service Duluth MN
305 PM CDT Mon Jul 3 2023

WIZ001-032030-
Douglas WI-
305 PM CDT Mon Jul 3 2023

...A STRONG THUNDERSTORM WILL IMPACT PORTIONS OF CENTRAL DOUGLAS
COUNTY THROUGH 330 PM CDT...

At 305 PM CDT, Doppler radar was tracking a strong thunderstorm 8
miles east of Foxboro, or 16 miles south of Superior, moving east at
15 mph.

HAZARD...Wind gusts up to 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow unsecured
         objects around. Minor hail damage to outdoor objects is
         possible.

Locations impacted include...
  Hawthorne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Anyone outdoors, including anyone on or in the water, should seek
shelter inside a sturdy building or hard topped vehicle.

&&

LAT...LON 4633 9228 4657 9219 4661 9172 4630 9174
TIME...MOT...LOC 2005Z 272DEG 15KT 4648 9210

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

Rothstein

Special Weather Statement
National Weather Service Duluth MN
315 PM CDT Mon Jul 3 2023

MNZ012-020-021-032045-
Northern Cook/Northern Lake MN-Southern Cook/North Shore MN-
Southern Lake/North Shore MN-
315 PM CDT Mon Jul 3 2023

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF SOUTHWESTERN COOK AND
SOUTHERN LAKE COUNTIES THROUGH 345 PM CDT...

At 314 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 8 miles northeast of Clear Lake, to near
Finland, to near Larsmont, moving east at 20 mph.

HAZARD...Wind gusts up to 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow unsecured
         objects around. Minor hail damage to outdoor objects is
         possible.

Strong thunderstorms will be near...
  Beaver Bay and Finland around 330 PM CDT.

Other locations in the path of these storms include Silver Bay,
Illgen City, Lutsen and Little Marais.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Anyone outdoors, including anyone on or in the water, should seek
shelter inside a sturdy building or hard topped vehicle.

&&

LAT...LON 4762 9063 4744 9099 4725 9121 4692 9174
      4696 9189 4746 9154 4781 9107 4769 9056
TIME...MOT...LOC 2014Z 281DEG 18KT 4771 9097 4738 9137 4701 9176

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

Rothstein

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