Alert archive / Minnesota / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 129, NWS Duluth, MN

September 14, 2017Cass County, Minnesota

NWS Duluth, MN issued this severe thunderstorm warning at Sep 14, 2017, 10:46 PM CDT for Cass County, Minnesota. It was in force for 29 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 14, 2017, 10:46 PM CDT (03:46 UTC)
Expired
Sep 14, 2017, 11:15 PM CDT
In force
29 min
Issued by
NWS Duluth, MN
Area
Storm-based polygon
Hail
1.5 in
Wind
60.0 mph

County Cass County, MN

The radar

The Duluth radar (KDLH), 161 km from the middle of the area, began a volume at 03:50 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

International Fa, MN (KINL), launched 00:00Z, 3.8 hours before the alert went out and 196 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, International Fa, MN at 00:00Z on 2017-09-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, International Fa, MN at 00:00Z on 2017-09-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -1 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
907 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
-1 m²/s²
0-3 km storm-relative helicity
99 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Duluth, MN wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 14, 10:35 PM CDT, 11 minutes earlier.

Area forecast discussion, Sep 14, 10:35 PM CDT, 11 minutes before
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Hazardous weather outlook, Sep 14, 10:16 PM CDT, 30 minutes before
Hazardous Weather Outlook
National Weather Service Duluth MN
1016 PM CDT Thu Sep 14 2017

MNZ010>012-018>021-025-026-033>038-WIZ001>004-006>009-151030-
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-
1016 PM CDT Thu Sep 14 2017

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

.DAY ONE...Tonight

Thunderstorms will continue overnight. A few storms may be strong
to severe over portions of northern Minnesota. Hail and gusty
winds are possible with these stronger storms. Heavy rain will
also be possible as showers and storms continue to form and move
across the same areas, possibly leading to flash flooding. A Flash
Flood Watch is in effect through 6 am from the Walker area east
northeast through the Arrowhead.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Strong northeast flow over western Lake Superior, down to the
Twin Ports area, on Friday will likely cause a high risk of
dangerous rip currents along Duluth's Park Point Beach and
Superior's Wisconsin Point Beach through the day.

Thunderstorms are possible across northeast Minnesota and
northwest Wisconsin Friday night through Saturday night. Some
storms Saturday afternoon and evening could be strong.

Periods of thunderstorms are possible across northeast Minnesota
and northwest Wisconsin Tuesday night through Wednesday.

.SPOTTER INFORMATION STATEMENT...

Skywarn Spotters may be needed tonight. Reports of heavy rain and
flooding would also be appreciated.

LSZ121-140>148-151030-
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-
1016 PM CDT Thu Sep 14 2017

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

.DAY ONE...Tonight

Thunderstorms are possible tonight. Some storms may contain hail
and gusty winds.

Northeast winds will create hazardous conditions for small craft
over far western Lake Superior tonight.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Northeast winds will continue to increase over western Lake
Superior late tonight and Friday. The wind and resulting waves
will likely result in widespread hazardous conditions for small
craft across western Lake Superior, especially along the South
Shore and Twin Ports area, until the winds and waves sufficiently
subside later Friday night.

Periods of thunderstorms are possible over western Lake Superior
Friday afternoon through Saturday night. Additional periods of
storms are possible Tuesday night and Wednesday.

Melde

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

In the hours before

Local storm report, Sep 14, 9:59 PM CDT, 47 minutes before
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Local storm report, Sep 14, 10:01 PM CDT, 45 minutes before
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Local storm report, Sep 14, 10:08 PM CDT, 38 minutes before
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Local storm report, Sep 14, 10:33 PM CDT, 13 minutes before
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Local storm report, Sep 14, 10:37 PM CDT, 9 minutes before
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Special weather statement, Sep 14, 10:44 PM CDT, 2 minutes before
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The office that day

Everything else NWS Duluth, MN issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 14, 7:05 PM CDTSpecial Weather StatementDLHCook25 min
Sep 14, 7:08 PM CDTSpecial Weather StatementDLHLake37 min
Sep 14, 7:23 PM CDTSmall Craft AdvisoryDLH45 hr
Sep 14, 7:37 PM CDTSpecial Marine WarningDLH53 min
Sep 14, 7:56 PM CDTSpecial Weather StatementDLHItasca19 min
Sep 14, 7:59 PM CDTSpecial Marine WarningDLH31 min
Sep 14, 8:09 PM CDTSpecial Weather StatementDLHLake21 min
Sep 14, 8:29 PM CDTAreal Flood AdvisoryDLHCook, Lake, Saint Louis6 hr
Sep 14, 8:31 PM CDTSpecial Marine WarningDLH59 min
Sep 14, 8:37 PM CDTSpecial Weather StatementDLHCass8 min
Sep 14, 8:47 PM CDTSpecial Weather StatementDLHCass13 min
Sep 14, 8:53 PM CDTSpecial Weather StatementDLHSaint Louis22 min
Sep 14, 9:03 PM CDTSpecial Weather StatementDLHCass12 min
Sep 14, 9:17 PM CDTFlash Flood WarningDLHLake, Saint Louis4 hr
Sep 14, 9:24 PM CDTSpecial Weather StatementDLHCass21 min
Sep 14, 9:39 PM CDTSpecial Weather StatementDLHItasca21 min
Sep 14, 9:47 PM CDTAreal Flood AdvisoryDLHCass, Itasca5 hr
Sep 14, 10:44 PM CDTSpecial Weather StatementDLHLake31 min
Sep 14, 10:54 PM CDTSpecial Weather StatementDLHItasca36 min
Sep 14, 11:01 PM CDTSpecial Weather StatementDLHSaint Louis14 min
Sep 14, 11:32 PM CDTSpecial Weather StatementDLHLake13 min
Sep 15, 3:55 AM CDTBeach Hazards StatementDLHCarlton, Saint Louis16 hr
Sep 15, 1:04 PM CDTSpecial Weather StatementDLHCrow Wing26 min
Sep 15, 1:36 PM CDTSpecial Weather StatementDLHAitkin24 min
Sep 15, 2:19 PM CDTSpecial Weather StatementDLHItasca26 min
Sep 15, 3:28 PM CDTSpecial Weather StatementDLHLake, Saint Louis32 min
Sep 15, 4:53 PM CDTSpecial Weather StatementDLHCrow Wing37 min
Sep 15, 1:56 PM CDTSpecial Weather StatementDLHBayfield34 min

Nearby

Severe Thunderstorm Warnings in Minnesota, 2017Every severe thunderstorm warning in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.