Severe Thunderstorm Warning 48, NWS Duluth, MN

Area Forecast Discussion
National Weather Service Duluth MN
938 PM CDT Wed Jul 8 2020

.UPDATE...
Issued at 933 PM CDT Wed Jul 8 2020

Will leave the Severe Thunderstorm Watch as is. SPC mesoscale
analysis and CAM trends through 02 UTC favor a strong to severe
thunderstorm threat into much of the night. Thunderstorms
developing across northeast South Dakota into west central
Minnesota are expected to continue to propagate northeast into the
night with sufficient instability and effective shear to support
at least a marginal severe threat. Precipitable water values near
1.8 inches with continued strong moisture transport via the low
level jet and training of storms supports an increasing flash
flood threat.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 305 PM CDT Wed Jul 8 2020

Severe weather is the focus in the short term, especially from late
afternoon into late evening. Latest satellite imagery was showing
cumulus growing over the western half of the Northland and radar
shows a few showers/storms have formed. These are elevated given
that substantial MLCIN remains across most of the area. However, the
RAP shows the MLCIN diminishing by late afternoon as most of the
cloud from the earlier convection has diminished and strong heating
was occurring. The surface cold and warm fronts in addition to
the low level jet of 25 to 35 knots, an upper wave, and jet
streak will all contribute to forcing and sustenance of the
storms. We should see thunderstorms increase in both coverage and
intensity between late this afternoon and early evening over
northern Minnesota and this evening over northern Wisconsin. All
modes of severe weather will be possible including large hail to
golfball size, damaging wind to 70 mph , flash flooding, and a
tornado or two. Plenty of instability will be present with MLCAPE
forecast to increase to 1500-3500 J/KG, deep layer shear from 25
to 35 knots will be supportive, as will steep mid level lapse
rates, and high PWAT values from 1.6 to 2.0 inches. Storm mode
should start out with some discreet cells but most of the CAMs
show coverage will transition to clusters or lines. Low level
hodographs show decent veering and the longer storms can remain
discreet the better the chance for a possible tornado. In addition
to the tornado, hail, and wind threat will be very heavy rain.
Several strong thunderstorm complexes may track over the same
areas leading to heavy rainfall. We tossed the idea around for a
Flash Flood Watch but opted to not issue at this time. Much of the
Northland has seen below normal precipitation over the past week
and in some areas of northern Minnesota, the past few weeks. That
said, localized flash flooding will be possible late today into
tonight. The storms are expected to diminish but not end entirely
late tonight.

Another round of storms will be possible on Thursday as the front is
moving through the region slowly. The best chance for strong to
severe storms will be over parts of northern Wisconsin which will
remain ahead of the front and should recover from overnight
convection. Elsewhere, we have POPs as far west as eastern Minnesota
and the Arrowhead which remain just ahead of the front. Highs will
be in the eighties but dewpoints will be lower than today, except in
northern Wisconsin where mid sixties to around seventy will occur
again.

.LONG TERM...(Friday through Wednesday)
Issued at 305 PM CDT Wed Jul 8 2020

The extended period will feature a building ridge over the west that
will last into the weekend as the northern portion of the ridge
moves east. An upper low will then move east and push the ridge east
backing the upper winds to more southwest late in the period as
troughing takes over.

Friday will be dry and warm with weak ridging. Highs will range from
around eighty to the mid eighties in northern Wisconsin. Dewpoints
will be lower though and be in the fifties. There will be a few
chances for showers/storms over the weekend as a couple shortwaves
move through the region. However, coverage of the showers/storms do
not look to be particularly high. Highs will again be from 77 to 85
with dewpoints from the mid fifties to lower sixties for most areas.

A brief lull in precipitation chances will occur Sunday night into
Monday across most of the Northland then we have POPs again Tuesday
and Wednesday as the upper trough moves closer to the Northland.
Highs from Monday through Wednesday will be from 78 to 85 for most
areas.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 638 PM CDT Wed Jul 8 2020

The main issue for this evenings terminals will be thunderstorm
chances. Several areas of thunderstorms have been occurring this
afternoon and evening so far. A weak MCV was moving through
northeast Minnesota and was at least partially responsible for the
storms over the Iron Range and far northern Wisconsin. Further
west and south, a cold and warm front were aiding in causing
showers/storms. The airmass over the region is quite moist and
unstable making it relatively easy to form storms. We still think
an increase in both coverage and intensity to the storms will
occur over the next 1 to 2 hours. The strongest storms may
produce large hail, damaging wind, frequent lightning, very heavy
rain, and possibly a tornado. Most of the storms will occur
through the late evening hours but it's possible they may last
through much of the night in some form. Most of the guidance
agrees that coverage will decrease between 09-12Z. Some fog and
stratus will be possible later tonight and could reduce conditions
to IFR or LIFR. The cold front will still be over far eastern
Minnesota by early Thursday afternoon and more thunderstorms will
be possible along and ahead of it.

&&

.MARINE...
Issued at 305 PM CDT Wed Jul 8 2020

Winds tonight into Friday will be 15 knots or less, outside of any
thunderstorms. We expect thunderstorms to develop this afternoon
into this evening with several rounds expected to affect Lake
Superior. Some of the storms could be severe and produce wind gusts
greater than 50 knots, large hail, frequent lightning, and very
heavy rainfall. Storm coverage is expected to peak this evening then
decrease overnight. More storms will be possible on Thursday,
although coverage is expected to be more isolated or scattered. Wind
direction will be mainly easterly tonight then become more southerly
for most areas on Thursday shifting to west to southwest on
Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  63  84  59  83 /  80  20  10   0
INL  62  83  58  79 /  10  10   0   0
BRD  65  84  59  84 /  80  10   0   0
HYR  65  85  60  84 /  60  40  20   0
ASX  65  87  62  86 /  80  40  10   0

&&

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

UPDATE...PA
SHORT TERM...Melde
LONG TERM...Melde
AVIATION...Melde
MARINE...Melde

Hazardous Weather Outlook
National Weather Service Duluth MN
345 PM CDT Wed Jul 8 2020

MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-091030-
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-
345 PM CDT Wed Jul 8 2020

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

.DAY ONE...This afternoon and Tonight

Thunderstorms will increase in coverage and intensity late this
afternoon into the evening then decrease late tonight. Some of
the storms may be severe with damaging winds to around 70 mph,
large hail to golf ball size, an isolated tornado or two,
dangerous lightning, and heavy rain possibly leading to flash
flooding are all threats. Storms will move over the same areas
leading to very heavy rainfall in spots.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Chances of thunderstorms will linger into Thursday and a few may
be strong to marginally severe over portions of north central
Wisconsin.

There will be periodic chances for more thunderstorms over the
weekend.

.SPOTTER INFORMATION STATEMENT...

Skywarn spotters will likely be needed yet this afternoon into the
evening over northern Minnesota and this evening over northwest
Wisconsin.

LSZ121-140>148-091030-
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-
345 PM CDT Wed Jul 8 2020

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

.DAY ONE...This afternoon and Tonight

Strong to severe thunderstorms are forecast to develop across
most of northeast Minnesota and northwest Wisconsin and push
across western Lake Superior late this afternoon and overnight.
Wind gusts in excess of 50 knots, large hail, frequent lightning,
and heavy rain are the primary threats with this activity.

In addition to the thunderstorm threat, fog will also be possible
and it could be dense at times.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Chances of thunderstorms will linger into Thursday and a few may
be strong during the afternoon and evening hours.

There will be periodic chances for more thunderstorms over the
weekend.

Melde

More information may be obtained at the following web address:
http://www.weather.gov/duluth (all lower case)

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DULUTH MN
923 PM CDT WED JUL 8 2020

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

0922 PM     HAIL             LEADER                  46.52N 94.65W
07/08/2020  E0.70 INCH       CASS               MN   PUBLIC

            HAIL ONGOING COVERING THE GROUND.

&&

Special Weather Statement
National Weather Service Duluth MN
924 PM CDT Wed Jul 8 2020

MNZ012-019-020-036>038-WIZ001-002-006-090300-
Northern Cook/Northern Lake-Central St. Louis-Southern Lake/North
Shore-Pine-Carlton/South St. Louis-South
Aitkin-Douglas-Bayfield-Burnett-
924 PM CDT Wed Jul 8 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN AITKIN...
PINE...SOUTHEASTERN ST. LOUIS...EASTERN CARLTON...SOUTHERN LAKE...
WEST CENTRAL BAYFIELD...DOUGLAS AND NORTHEASTERN BURNETT COUNTIES...

At 923 PM CDT, strong thunderstorms were along a line extending from
Thomas Lake Near Brimson, to near Duluth, to 8 miles northwest of
Hinckley, and moving east at 55 mph.

Wind gusts up to 40 mph, dime size hail, heavy downpours, and
frequent cloud to ground lightning can be expected with these
storms. Dime size hail has occurred with this line of storms near
Esko.

Locations impacted include...
Duluth, Superior, Cloquet, Hermantown, Two Harbors, Proctor,
Sandstone, Silver Bay, Hawthorne, Lake Nebagamon, Scanlon, Carlton,
Maple, Brule, Mahtowa, Barnum, Poplar, Solon Springs, Oulu, and
Willow River.

Seek shelter inside a sturdy building and away from windows until
these storms pass. Get off area lakes and seek shelter on shore in a
sturdy shelter or a hard topped vehicle.

LAT...LON 4606 9305 4616 9305 4616 9319 4684 9240
      4739 9202 4746 9102 4715 9136 4678 9203
      4673 9196 4673 9179 4686 9134 4676 9138
      4589 9228
TIME...MOT...LOC 0223Z 268DEG 46KT 4726 9172 4675 9215 4610 9305

Melde

Special Weather Statement
National Weather Service Duluth MN
927 PM CDT Wed Jul 8 2020

WIZ003-004-008-090245-
Iron-Ashland-Sawyer-
927 PM CDT Wed Jul 8 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT CENTRAL IRON...SOUTHERN
ASHLAND AND NORTHEASTERN SAWYER COUNTIES...

At 927 PM CDT, strong thunderstorms were along a line extending from
Upson, to near Glidden, to near Clam Lake, and moving southeast at 15
mph.

Wind gusts up to 40 mph and dime size hail can be expected with these
storms.

These storms will be near...
  Upson and Glidden around 930 PM CDT.

Other locations impacted by these storms include Island Lake Iron
County.

Seek shelter inside a sturdy building and away from windows until
these storms pass. Get off area lakes and seek shelter on shore in a
sturdy shelter or a hard topped vehicle.

LAT...LON 4605 9026 4602 9088 4614 9110 4615 9059
      4640 9041 4633 9008
TIME...MOT...LOC 0227Z 295DEG 12KT 4637 9037 4613 9050 4612 9092

Wolfe

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DULUTH MN
932 PM CDT WED JUL 8 2020

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

0926 PM     HAIL             1 SSE CLOQUET           46.71N 92.45W
07/08/2020  M0.25 INCH       CARLTON            MN   TRAINED SPOTTER

&&

JDS

Special Weather Statement
National Weather Service Duluth MN
932 PM CDT Wed Jul 8 2020

MNZ025-033-034-090300-
Crow Wing-North Cass-South Cass-
932 PM CDT Wed Jul 8 2020

...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT SOUTHERN CASS AND
NORTHERN CROW WING COUNTIES...

At 931 PM CDT, an area of strong thunderstorms was near Pequot
Lakes, or 16 miles northwest of Brainerd, moving east at 30 mph. The
area of strong storms reached to near Pine River and down to Gull
Lake.

Wind gusts up to 45 mph, half inch diameter hail, heavy downpours,
and frequent cloud to ground lightning can be expected with these
storms.

Locations impacted include...
Crosby, Breezy Point, Pequot Lakes, Crosslake, Nisswa, Pine River,
Emily, Fifty Lakes, Cuyuna, Gull Lake, Lake Shore, East Gull Lake,
Mission, Jenkins, Wolford, Chickamaw Beach, Trommald, Manhattan
Beach, Lower Hay Lake, and Upper Mission Lake.

Seek shelter inside a sturdy building and away from windows until
these storms pass. Get off area lakes and seek shelter on shore in a
sturdy shelter or a hard topped vehicle.

LAT...LON 4664 9459 4692 9405 4655 9380 4652 9381
      4642 9450
TIME...MOT...LOC 0231Z 252DEG 26KT 4656 9436

Melde