Alert archive / Minnesota / Severe Thunderstorm Warnings in 2019

Severe Thunderstorm Warning 170, NWS Grand Forks, ND

August 20, 20195 counties in Minnesota; Cass County, Traill County, North Dakota

NWS Grand Forks, ND issued this severe thunderstorm warning at Aug 20, 2019, 4:25 AM CDT for 5 counties in Minnesota; Cass County, Traill County, North Dakota. It was in force for 65 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
Aug 20, 2019, 4:25 AM CDT (09:25 UTC)
Expired
Aug 20, 2019, 5:30 AM CDT
In force
65 min
Issued by
NWS Grand Forks, ND
Area
Storm-based polygon
Hail
1.75 in
Wind
60.0 mph

Counties Becker County, MN, Clay County, MN, Clearwater County, MN, Mahnomen County, MN, Norman County, MN, Cass County, ND, Traill County, ND

The radar

The Fargo/Grand Forks radar (KMVX), 84 km from the middle of the area, began a volume at 09:28 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

Minneapolis, MN (KMPX), launched 00:00Z, 9.4 hours before the alert went out and 336 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, Minneapolis, MN at 00:00Z on 2019-08-20Temperature 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, Minneapolis, MN at 00:00Z on 2019-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 26 square meters per square second.19395878Sfc1 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
1590 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
26 m²/s²
0-3 km storm-relative helicity
23 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 Grand Forks, ND wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 20, 2:36 AM CDT, 1 hour 49 minutes earlier.

Area forecast discussion, Aug 20, 2:36 AM CDT, 1 hour 49 minutes before
Area Forecast Discussion
National Weather Service Grand Forks ND
236 AM CDT Tue Aug 20 2019

.SHORT TERM...(Today and tonight)
Issued at 236 AM CDT Tue Aug 20 2019

There have been a couple severe thunderstorm warnings early this
morning, but so far nothing really substantial has taken off. The
Mayville radar currently shows activity extending from near
Jamestown up into the Devils Lake region and northern Red River
Valley. The system is a little disjointed overall, with the main
surface low just southeast of Minot. There is a boundary extending
northeast from this low, basically along a Rugby to Walhalla line,
with south winds south of the line and north winds to the north of
it. However, it is not getting a really strong push of either cold
air or strong winds behind it. Instead, the storms so far have
been based higher, feeding off the low level warm advection and
the 850mb jet.

Basically these features will translate eastward overnight, which
may allow for a few storms to pulse up to severe levels. Most high
resolution model guidance wants to bring an upswing in this
activity as it moves into the northern Red River Valley and
adjacent areas of northwest Minnesota in the pre-dawn hours. The
area of northwest Minnesota was the area SPC upgraded into a
slight risk for severe weather earlier this past evening. If there
was a stronger front would have much higher confidence in an
upswing in storm activity. As it sits now, hard to believe more
than scattered storm activity will continue, bringing more general
storms than severe storms. So will just continue to monitor
conditions through the rest of the night. Removed the severe
wording for now and reduced precipitation chances into more of a
50 to 60 percent range. If an upswing does happen to occur or the
storms begin to show more organization, will update the forecast
accordingly.

The storms should exit the eastern or southeastern FA sometime by
mid to late morning. The lingering cloud cover should also exit
off to the east, resulting in another mainly sunny day. Breezy
north winds will arrive by afternoon, but they will decrease
again by early evening. Tonight will feel a little fall like
again, as temperatures fall under clear skies and light winds.

.LONG TERM...(Wednesday through Monday)
Issued at 236 AM CDT Tue Aug 20 2019

Wednesday should continue with the north-northwest winds, but not
quite as gusty. Expect a good amount of sun again with coolish
highs in the 70s.

For Wednesday through Friday, quiet and slightly cooler than normal
weather develops as strong surface high pressure builds through the
Northern Plains. This will yield daily high temperatures in the 70s
and overnight lows in the 40s and 50s. Initially, cool and dry
northwest flow aloft persists upstream of an upper low near Hudson
Bay, but by Thursday, this system begins to progress eastward,
giving way to upper level ridging building into the Northern Plains
and Canadian Prairie. The influence of ridging will linger into
early Friday, but low level warm air advection will have little time
to take hold before the next disturbance advances toward the Plains
heading into the weekend.

For Friday through the weekend, chances for showers and storms
develop as the pattern becomes more active with multiple rounds of
upper level shortwaves progressing into the Northern Plains.
Confidence in timing and placement of these features is low at this
point, but ensemble guidance suggests more likely off and on rain in
the region with higher rain chances on Friday/Friday night and
Sunday into Monday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1144 PM CDT Mon Aug 19 2019

Scattered t-storms thru the night/early Tuesday which may affect
TAF sites or nearby. Outside of any storms VFR conditions. Tuesday
daytime will see north wind increase to 10-15 kts with gusts 20
kts at times. A period of MVFR cigs psbl around or just past 12z
esp in the RRV and MN just behind the cold front.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&

SHORT TERM...Godon
LONG TERM...Godon/BP
AVIATION...Riddle
Hazardous weather outlook, Aug 20, 3:15 AM CDT, 1 hour 10 minutes before
Hazardous Weather Outlook
National Weather Service Grand Forks ND
315 AM CDT Tue Aug 20 2019

MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024-
026>030-038-039-049-052>054-210815-
West Polk-Norman-Clay-Kittson-Roseau-Lake Of The Woods-
West Marshall-East Marshall-North Beltrami-Pennington-Red Lake-
East Polk-North Clearwater-South Beltrami-Mahnomen-
South Clearwater-Hubbard-West Becker-East Becker-Wilkin-
West Otter Tail-East Otter Tail-Wadena-Grant-Towner-Cavalier-
Pembina-Benson-Ramsey-Eastern Walsh County-Eddy-Nelson-
Grand Forks-Griggs-Steele-Traill-Barnes-Cass-Ransom-Sargent-
Richland-Western Walsh County-
315 AM CDT Tue Aug 20 2019

This hazardous weather outlook is for portions of eastern North
Dakota, west central and northwest Minnesota.

.DAY ONE...Today and Tonight

Scattered severe thunderstorms are possible into the morning
hours, especially along the Red River Valley into adjacent areas
of northwest and west central Minnesota. The main hazards will be
large hail up to golf ball size and damaging wind gusts up to 60
mph.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Periodic thunderstorms are possible from Thursday night through
Monday.

.SPOTTER INFORMATION STATEMENT...

Weather spotters may be needed.

In the hours before

Local storm report, Aug 19, 11:37 PM CDT, 4 hours 48 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND FORKS ND
1137 PM CDT MON AUG 19 2019

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

1115 PM     HAIL             4 ENE LEEDS             48.31N 99.36W
08/19/2019  E1.00 INCH       Benson             ND   BROADCAST MEDIA

            MEDIA RECEIVED PHOTO OF QUARTER SIZED DIAMETER HAIL

&&

BP
Local storm report, Aug 20, 1:33 AM CDT, 2 hours 52 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
133 AM CDT TUE AUG 20 2019

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

1230 AM     HAIL             2 N DEVILS LAKE         48.14N 98.87W
08/20/2019  M1.00 INCH       Ramsey             ND   PUBLIC

&&

DRIDDLE
Special weather statement, Aug 20, 2:17 AM CDT, 2 hours 8 minutes before
Special Weather Statement
National Weather Service Grand Forks ND
217 AM CDT Tue Aug 20 2019

NDZ027-029-030-200815-
Steele ND-Traill ND-Grand Forks ND-
217 AM CDT Tue Aug 20 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN GRAND FORKS...
NORTHWESTERN TRAILL AND NORTHEASTERN STEELE COUNTIES UNTIL 315 AM
CDT...

At 216 AM CDT, Doppler radar was tracking a strong thunderstorm near
Logan Center, or 31 miles west of Grand Forks, moving southeast at 35
mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

This strong thunderstorm will be near...
  Kempton around 225 AM CDT.
  Northwood around 230 AM CDT.
  Hatton around 245 AM CDT.
  Holmes around 250 AM CDT.
  Reynolds around 305 AM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Grand Forks.

&&

LAT...LON 4770 9787 4804 9786 4784 9701 4747 9703
TIME...MOT...LOC 0716Z 297DEG 33KT 4780 9772

Riddle
Special weather statement, Aug 20, 2:24 AM CDT, 2 hours 1 minute before
Special Weather Statement
National Weather Service Grand Forks ND
224 AM CDT Tue Aug 20 2019

NDZ026-200815-
Nelson ND-
224 AM CDT Tue Aug 20 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN NELSON COUNTY UNTIL 315
AM CDT...

At 223 AM CDT, Doppler radar was tracking a strong thunderstorm 5
miles south of Lakota, or 27 miles southeast of Devils Lake, moving
east at 30 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

This storm will affect areas east of Stump Lake to south of
Michigan.  Other thunderstorms are occurring in the area as well.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Grand Forks.

&&

LAT...LON 4806 9835 4790 9788 4767 9789 4782 9850
TIME...MOT...LOC 0723Z 287DEG 25KT 4795 9832

Riddle
Local storm report, Aug 20, 3:00 AM CDT, 1 hour 25 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND FORKS ND
300 AM CDT TUE AUG 20 2019

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

0255 AM     HAIL             HATTON                  47.64N 97.46W
08/20/2019  E1.50 INCH       TRAILL             ND   PUBLIC

            FACEBOOK PHOTO OF LARGE HAIL UP TO PING PONG BALL SIZE IN
            HATTON

&&

BP
Local storm report, Aug 20, 3:49 AM CDT, 36 minutes before
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The office that day

Everything else NWS Grand Forks, ND issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 20, 3:10 AM CDTSevere Thunderstorm WarningFGFClay, Norman53 min
Aug 20, 3:43 AM CDTSevere Thunderstorm WarningFGFNorman, Polk18 min
Aug 20, 4:07 AM CDTSevere Thunderstorm WarningFGFClay, Norman23 min
Aug 20, 4:30 AM CDTSpecial Weather StatementFGFLake of the Woods30 min
Aug 20, 5:01 AM CDTSpecial Weather StatementFGFBecker14 min
Aug 20, 5:13 AM CDTSevere Thunderstorm WarningFGFBecker, Clearwater, Hubbard, Mahnomen, Otter Tail, Wadena62 min
Aug 20, 5:28 AM CDTSpecial Weather StatementFGFBeltrami, Clearwater47 min
Aug 20, 6:09 AM CDTSevere Thunderstorm WarningFGFOtter Tail, Wadena36 min
Aug 19, 11:04 PM CDTSevere Thunderstorm WarningFGFBenson, Ramsey56 min
Aug 20, 12:00 AM CDTSevere Thunderstorm WarningFGFBenson, Ramsey45 min
Aug 20, 12:44 AM CDTSevere Thunderstorm WarningFGFBenson, Nelson, Ramsey61 min
Aug 20, 2:17 AM CDTSpecial Weather StatementFGFGrand Forks58 min
Aug 20, 2:24 AM CDTSpecial Weather StatementFGFNelson51 min
Aug 20, 2:39 AM CDTSevere Thunderstorm WarningFGFGrand Forks, Steele, Traill66 min

Nearby

Severe Thunderstorm Warnings in Minnesota, 2019Severe Thunderstorm Warnings in North Dakota, 2019Every severe thunderstorm warning in 2019

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.