Alert archive / Minnesota / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 65, NWS Twin Cities, MN

July 28, 2021Washington County, Minnesota; Saint Croix County, Wisconsin

NWS Twin Cities, MN issued this severe thunderstorm warning at Jul 28, 2021, 9:37 PM CDT for Washington County, Minnesota; Saint Croix County, Wisconsin. It was in force for 38 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 28, 2021, 9:37 PM CDT (02:37 UTC)
Expired: Jul 28, 2021, 10:15 PM CDT
In force: 38 min
Issued by: NWS Twin Cities, MN
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 70.0 mph

Counties Washington County, MN, Saint Croix County, WI

The radar

The Minneapolis radar (KMPX), 69 km from the middle of the area, began a volume at 02:40 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.

What was reported inside it

Time	Report	Where	Remark
Jul 28, 10:15 PM CDT	TSTM WND DMG	4 S Roberts, WI	A BARN WAS BLOWN DOWN, BUT NO OTHER STRUCTURAL DAMAGE WAS REPORTED. TIME APPROXIMATED BASED ON RADAR.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 28, 7:17 PM CDT	Severe Thunderstorm Watch PDS	SPC	7 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 2.6 hours before the alert went out and 72 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 4815 J/kg
Mixed-layer CIN: -38 J/kg
Mixed-layer LCL: 1185 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 374 m²/s²
0-3 km storm-relative helicity: 461 m²/s²
Significant tornado parameter: 8.9
Supercell composite: 48.1

Open this sounding in Storm Lab

The text

As transmitted.

316 
WUUS53 KMPX 290237
SVRMPX
MNC163-WIC109-290315-
/O.NEW.KMPX.SV.W.0065.210729T0237Z-210729T0315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Twin Cities/Chanhassen MN
937 PM CDT Wed Jul 28 2021

The National Weather Service in the Twin Cities has issued a

* Severe Thunderstorm Warning for...
  Eastern Washington County in east central Minnesota...
  Western St. Croix County in west central Wisconsin...

* Until 1015 PM CDT.

* At 936 PM CDT, a severe thunderstorm was located near Somerset, or
  21 miles north of River Falls, moving southeast at 45 mph.

  HAZARD...70 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect considerable 
           tree damage. Wind damage is also likely to mobile homes, 
           roofs, and outbuildings.

* This severe thunderstorm will be near...
  Stillwater and Somerset around 940 PM CDT.
  Bayport around 945 PM CDT.
  Hudson and North Hudson around 950 PM CDT.
  Roberts around 955 PM CDT.

Other locations in the path of this severe thunderstorm include River
Falls.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Intense thunderstorm lines can produce brief tornadoes and widespread
significant wind damage. Although a tornado is not immediately
likely, it is best to move to an interior room on the lowest floor of
a building. This storm may cause serious injury and significant
property damage.

&&

LAT...LON 4522 9293 4520 9267 4487 9237 4486 9283
TIME...MOT...LOC 0236Z 330DEG 40KT 4516 9273 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...70MPH
 
$$

JLT

1 follow-up statement

801 
WWUS53 KMPX 290255
SVSMPX

Severe Weather Statement
National Weather Service Twin Cities/Chanhassen MN
955 PM CDT Wed Jul 28 2021

MNC163-WIC109-290315-
/O.CON.KMPX.SV.W.0065.000000T0000Z-210729T0315Z/
Washington MN-St. Croix WI-
955 PM CDT Wed Jul 28 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 PM CDT
FOR SOUTHEASTERN WASHINGTON AND WESTERN ST. CROIX COUNTIES...

At 954 PM CDT, a severe thunderstorm was located near Roberts, or 11
miles north of River Falls, moving southeast at 35 mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

Locations impacted include...
  Roberts and River Falls.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Intense thunderstorm lines can produce brief tornadoes and widespread
significant wind damage. Although a tornado is not immediately
likely, it is best to move to an interior room on the lowest floor of
a building. This storm may cause serious injury and significant
property damage.

&&

LAT...LON 4514 9290 4515 9262 4487 9237 4486 9283
TIME...MOT...LOC 0254Z 331DEG 29KT 4503 9263 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...70MPH
 
$$

JLT

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 28, 8:55 PM CDT	Severe Thunderstorm Warning	MPX	Chisago	50 min
Jul 28, 10:21 PM CDT	Severe Thunderstorm Warning	MPX	Washington	24 min
Jul 28, 10:57 PM CDT	Severe Thunderstorm Warning	MPX	Goodhue	48 min
Jul 28, 7:19 PM CDT	Special Weather Statement	MPX	Rusk	26 min
Jul 28, 7:37 PM CDT	Severe Thunderstorm Warning	MPX	Rusk	23 min
Jul 28, 7:43 PM CDT	Severe Thunderstorm Warning	MPX	Barron, Polk, Rusk	32 min
Jul 28, 8:01 PM CDT	Severe Thunderstorm Warning	MPX	Barron, Chippewa, Rusk	44 min
Jul 28, 8:09 PM CDT	Tornado Warning	MPX	Polk	35 min
Jul 28, 8:46 PM CDT	Severe Thunderstorm Warning	MPX	Barron, Chippewa, Rusk	59 min
Jul 28, 9:08 PM CDT	Tornado Warning	MPX	Chippewa	37 min
Jul 28, 9:25 PM CDT	Severe Thunderstorm Warning	MPX	Dunn, Saint Croix	65 min
Jul 28, 9:30 PM CDT	Severe Thunderstorm Warning	MPX	Chippewa, Eau Claire	60 min
Jul 28, 9:36 PM CDT	Tornado Warning	MPX	Saint Croix	24 min
Jul 28, 9:55 PM CDT	Tornado Warning	MPX	Saint Croix	35 min
Jul 28, 10:09 PM CDT	Severe Thunderstorm Warning	MPX	Dunn, Pepin, Pierce, Saint Croix	51 min
Jul 28, 10:18 PM CDT	Severe Thunderstorm Warning	MPX	Dunn, Eau Claire, Pepin	42 min
Jul 28, 10:36 PM CDT	Severe Thunderstorm Warning	MPX	Pepin	39 min

Nearby

Severe Thunderstorm Warnings in Minnesota, 2021 Severe Thunderstorm Warnings in Wisconsin, 2021 Every severe thunderstorm warning in 2021

Sources

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