Alert archive / Minnesota / Tornado Warnings in 2011

Tornado Warning 12, NWS Twin Cities, MN

May 21, 2011Hennepin County, Isanti County, Minnesota

NWS Twin Cities, MN issued this tornado warning at May 21, 2011, 6:37 PM CDT for Hennepin County, Isanti County, Minnesota. It was in force for 23 min. 4 reports 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
May 21, 2011, 6:37 PM CDT (23:37 UTC)
Expired
May 21, 2011, 7:00 PM CDT
In force
23 min
Issued by
NWS Twin Cities, MN
Area
Storm-based polygon

Counties Hennepin County, MN, Isanti County, MN

The radar

The Minneapolis radar (KMPX), 39 km from the middle of the area, began a volume at 23:40 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

TimeReportWhereRemark
May 21, 6:38 PM CDTFUNNEL CLOUDW Plymouth, MNROTATING WALL CLOUD
May 21, 6:51 PM CDTHAIL 0.25Plymouth, MN
May 21, 6:52 PM CDTHAIL 0.25Plymouth, MN
May 21, 6:55 PM CDTFUNNEL CLOUDMaple Grove, MNROTATING WALL CLOUD

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

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 11.6 hours before the alert went out and 39 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 12:00Z on 2011-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 12:00Z on 2011-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 206 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
2 J/kg
Mixed-layer CIN
-114 J/kg
Mixed-layer LCL
474 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
206 m²/s²
0-3 km storm-relative helicity
240 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

197 
WFUS53 KMPX 212337
TORMPX
MNC053-059-220000-
/O.NEW.KMPX.TO.W.0012.110521T2337Z-110522T0000Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
637 PM CDT SAT MAY 21 2011

THE NATIONAL WEATHER SERVICE IN THE TWIN CITIES HAS ISSUED A

* TORNADO WARNING FOR...
  SOUTHWESTERN ISANTI COUNTY IN EAST CENTRAL MINNESOTA...
  NORTH CENTRAL HENNEPIN COUNTY IN EAST CENTRAL MINNESOTA...

* UNTIL 700 PM CDT

* AT 636 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A TORNADO NEAR   
  NEAR MEDINA... RADAR SHOWED THE TORNADIC STORM MOVING NORTH AT 20 
  MPH.

* LOCATIONS IN THE WARNING INCLUDE...
  CORCORAN...
  MAPLE GROVE...
  OSSEO...
  DAYTON...
  ROGERS...
  CHAMPLIN...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

WHEN A TORNADO WARNING IS ISSUED BASED ON RADAR...IT MEANS THAT
STRONG ROTATION HAS BEEN DETECTED IN THE STORM. A TORNADO MAY ALREADY
BE ON THE GROUND...OR IS EXPECTED TO DEVELOP SHORTLY.

&&

LAT...LON 4542 9320 4541 9350 4524 9350 4522 9344
      4515 9334 4499 9348 4502 9366 4523 9359
      4525 9351 4541 9350 4543 9352 4550 9350
TIME...MOT...LOC 2337Z 202DEG 17KT 4506 9354

$$

JLT
2 follow-up statements
106 
WWUS53 KMPX 212340
SVSMPX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
640 PM CDT SAT MAY 21 2011

MNC059-212355-
/O.CAN.KMPX.TO.W.0012.000000T0000Z-110522T0000Z/
ISANTI MN-
640 PM CDT SAT MAY 21 2011

...THE TORNADO WARNING FOR SOUTHWESTERN ISANTI COUNTY IS CANCELLED...


LAT...LON 4522 9344 4515 9334 4499 9348 4502 9366
      4523 9359 4524 9352
TIME...MOT...LOC 2340Z 202DEG 17KT 4507 9353

$$

MNC053-220000-
/O.CON.KMPX.TO.W.0012.000000T0000Z-110522T0000Z/
HENNEPIN MN-
640 PM CDT SAT MAY 21 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTH CENTRAL HENNEPIN
COUNTY UNTIL 700 PM CDT...

AT 636 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A TORNADO.  THIS 
TORNADO WAS LOCATED NEAR MEDINA...MOVING NORTH AT 20 MPH.

LOCATIONS IMPACTED INCLUDE...
  CORCORAN...MAPLE GROVE...OSSEO...DAYTON...ROGERS AND CHAMPLIN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOTORISTS SHOULD NOT TAKE SHELTER UNDER HIGHWAY OVERPASSES. AS A LAST
RESORT... EITHER PARK YOUR VEHICLE AND STAY PUT...OR ABANDON YOUR
VEHICLE AND LIE DOWN IN A LOW LYING AREA.

&&

LAT...LON 4522 9344 4515 9334 4499 9348 4502 9366
      4523 9359 4524 9352
TIME...MOT...LOC 2340Z 202DEG 17KT 4507 9353

$$

JLT
164 
WWUS53 KMPX 212351
SVSMPX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
651 PM CDT SAT MAY 21 2011

MNC053-220000-
/O.CON.KMPX.TO.W.0012.000000T0000Z-110522T0000Z/
HENNEPIN MN-
651 PM CDT SAT MAY 21 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTH CENTRAL HENNEPIN
COUNTY UNTIL 700 PM CDT...

AT 645 PM CDT...NATIONAL WEATHER SERVICE RADAR INDICATED A SEVERE
THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS STORM 
WAS LOCATED EAST OF HAMEL...MOVING NORTHEAST AT 15 MPH.

TRAINED SPOTTERS EARLIER REPORTED A BRIEF TOUCHDOWN NEAR MEDINA WITH 
THIS STORM. 

LOCATIONS IMPACTED INCLUDE...
  MAPLE GROVE...OSSEO...CHAMPLIN...DAYTON AND ROGERS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
IN THE TWIN CITIES.

&&

LAT...LON 4522 9344 4515 9334 4499 9348 4502 9366
      4523 9359 4524 9352
TIME...MOT...LOC 2350Z 221DEG 13KT 4508 9349

$$

JLT

The office that day

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

IssuedProductOfficeCountiesLasted
May 21, 3:20 PM CDTSpecial Weather StatementMPXRenville40 min
May 21, 3:57 PM CDTSpecial Weather StatementMPXMcLeod, Meeker, Wright63 min
May 21, 4:11 PM CDTSevere Thunderstorm WarningMPXMcLeod, Meeker, Renville, Sibley, Wright49 min
May 21, 4:39 PM CDTSevere Thunderstorm WarningMPXMcLeod, Meeker, Wright66 min
May 21, 5:11 PM CDTSpecial Weather StatementMPXChippewa, Swift49 min
May 21, 5:25 PM CDTSevere Thunderstorm WarningMPXChippewa, Pope, Swift50 min
May 21, 5:35 PM CDTSevere Thunderstorm WarningMPXCarver, McLeod, Wright55 min
May 21, 6:13 PM CDTSevere Thunderstorm WarningMPXHennepin, Wright62 min
May 21, 6:54 PM CDTSpecial Weather StatementMPXAnoka, Sherburne51 min

Nearby

Tornado Warnings in Minnesota, 2011Every tornado warning in 2011Tornadoes in 2011

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.