Alert archive / Minnesota / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 66, NWS Twin Cities, MN

July 20, 1987Carver County, Hennepin County, Minnesota

NWS Twin Cities, MN issued this severe thunderstorm warning at Jul 20, 1987, 10:36 PM CDT for Carver County, Hennepin County, Minnesota. It was in force for 54 min.

The area

The counties it named.

The facts

Issued
Jul 20, 1987, 10:36 PM CDT (03:36 UTC)
Expired
Jul 20, 1987, 11:30 PM CDT
In force
54 min
Issued by
NWS Twin Cities, MN
Area
Whole counties

Counties Carver County, MN, Hennepin County, MN

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Minneapolis, MN (KSTC), launched 00:00Z, 3.6 hours before the alert went out and 8 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 1987-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3871 joules per kilogram.LCLEL10008507005003002001001 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 1987-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 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
3871 J/kg
Mixed-layer CIN
-1 J/kg
Mixed-layer LCL
860 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
73 m²/s²
Significant tornado parameter
0.9
Supercell composite
4.4

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KMSP 210336
SVRMSP
MNC019-053-210430-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MINNEAPOLIS MN
1036 PM CDT MON JUL 20 1987

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM 
WARNING EFFECTIVE UNTIL 1130 PM CDT FOR PEOPLE IN THE FOLLOWING 
COUNTIES OF

EAST CENTRAL MINNESOTA...
 NORTHEAST CARVER AND HENNEPIN


AT..1030 PM CDT..A CLUSTER OF SEVERE THUNDERSTORMS WAS LOCATED
ACROSS MUCH OF HENNEPIN COUNTY AS WELL AS NORTHEAST CARVER
COUNTY OF THE TWIN CITIES METROPOLITAN AREA.

THESE THUNDERSTORMS WERE SLOWLY MOVING EAST NORTHEAST AT ABOUT 15
MILES AN HOUR AND WILL BE AFFECTING AREAS INCLUDING MINNEAPOLIS..
BLOOMINGTON..MINNETONKA..CHANHASSEN AND BROOKLYN CENTER.

DOWNED TREES WERE REPORTED IN EXCELSIOR WITH DIME SIZE HAIL AND
HIGH WINDS IN MOUND. PERSONS SHOULD ALSO BE AWARE OF FLOODED ROADS
AND FREQUENT DANGEROUS LIGHTNING WITH THIS SEVERE ACTIVITY.

REMEMBER SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60
MPH..DESTRUCTIVE HAIL..DEADLY LIGHTNING AND VERY HEAVY RAIN. ALSO
SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE A TORNADO WITH
LITTLE OR NO ADVANCE WARNING..SO BE ON THE LOOKOUT AND BE PREPARED
TO; MOVE TO A PLACE OF SAFETY IF ONE IS SPOTTED.

MATHEWS

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.

In the hours before

Special weather statement, Jul 20, 6:21 PM CDT, 4 hours 15 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MINNEAPOLIS/ST PAUL MN
615 PM CDT MON JUL 20 1987

    ..THUNDERSTORMS TO AFFECT THE LAKE MINNETONKA AREA..

A STRONG THUNDERSTORM HAS BEEN DEVELOPING RAPIDLY OVER WESTERN HENNEPIN
COUNTY IN THE MOUND AND INDEPENDENCE AREA. THIS THUNDERSTORM WAS SLOWLY
MOVING TO THE EAST SOUTHEAST AND IT WILL MOVE ACROSS PARTS OF LAKE
MINNETONKA THROUGH 700 PM.

SOME LIGHTNING..GUSTY WINDS AND HEAVY RAINS ARE POSSIBLE WITH THIS STORM.

PERSONS BOATING OR FISHING ON LAKE MINNETONKA SHOULD MAKE PLANS NOW TO
HEAD FOR SAFE HARBOR UNTIL THE THUNDERSTORMS PASS BY THE LAKE.

AT 615 PM CDT..OTHER THUNDERSTORMS WERE FORMING OVER SCOTT..WESTERN ANOKA
AND WRIGHT COUNTIES OF THE WESTERN METROPOLITAN AREA.

THEY WERE MOVING EAST AT ABOUT 20 MILES AN HOUR.
SWANBERG
Special weather statement, Jul 20, 8:04 PM CDT, 2 hours 32 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MINNEAPOLIS/ST PAUL MN
800 PM CDT MON JUL 20 1987

    ..INTENSE THUNDERSTORMS ACROSS SOUTHERN AND CENTRAL MINNESOTA AND
      NORTHWEST WISCONSIN..

AT 800 PM CDT..THE STRONGEST THUNDERSTORMS WERE OCCURRING IN AND AROUND
THE TWIN CITIES AREA WITH HAIL..HIGH WINDS AND VERY HEAVY RAINS.

SMALL HAIL..WINDS GUSTING TO 50 MPH AND TORRENTIAL RAINS CAN BE EXPECTED
ACROSS THE METROPOLITAN AREA rUNTIL AT LEAST 930 PM.

STREET FLOODING CAN ALSO BE EXPECTED.
SWANBERG
SWANBERG
Special weather statement, Jul 20, 9:20 PM CDT, 1 hour 16 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ST CLOUD MN
915 PM CDT MON JUL 20 1987

...SEVERE THUNDERSTORM WATCH FOR CENTRAL AND SOUTHERN MINNESOTA UNTIL
100 AM CDT...

RADAR SHOWED A LINE OF VERY INTENSE THUNDERSTORMS IN MINNESOTA FROM
THE SOUTH DAKOTA BORDER AND YELLOW MEDICINE COUNTY BORDER EAST
THROUGH CHIPPEWA AND KANDIYOHI COUNTY.

THESE THUNDERSTORMS HAVE PRODUCED PEA SIZE HAIL AND BRIEF HEAVY RAIN
AND ONE REPORT OF WIND GUST TO 50 MPH.

THE THUNDERSTORMS CONTINUE TO MOVE EAST AT 30 MILES AN HOUR.

ALTHOUGH NO SEVERE WEATHER HAS BEEN REPORTED THE POTENTIAL IS HIGH
FOR SEVERE DEVELOPMENT.  PLEASE STAY TUNED TO NOAA WEATHER
RADIO...TELEVISION AND YOUR LOCAL RADIO STATION FOR FUTURE UPDATES OR
WARNINGS.

FRASER
Special weather statement, Jul 20, 9:26 PM CDT, 1 hour 10 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MINNEAPOLIS/ST PAUL MN
925 PM CDT MON JUL 20 1987

...PART OF SEVERE THUNDERSTORM WATCH NUMBER 409 CLEARED...

THE NATIONAL WEATHER SERVICE HAS CLEARED THE NORTH PORTION OF SEVERE
THUNDERSTORM WATCH NUMBER 409 ISSUED EARLIER THIS EVENING.

THE WATCH IS CLEARED NORTH OF A LINE FORM BROWNS VALLEY IN WEST
CENTRAL MINNESOTA TO ALEXANDRIA TO SAUK RAPIDS TO FOLEY TO CAMBRIDGE
AND TO CENTER CITY IN EAST CENTRAL MINNESOTA.

THE COUNTIES THAT ARE CLEARED FROM THE WATCH ARE...

IN WEST CENTRAL MINNESOTA...TRAVERSE..GRANT..DOUGLAS..OTTERTAIL..
AND WILKIN.

IN CENTRAL......TODD..MORRISON..SOUTHERN CROW WING..
<
IN EAST CENTRAL.....MILLE LACS..KANABEC..ISANTI..CHISAGO..PINE..

THE TWIN CITIES METRO AREA IS STILL INCLUDED IN THE SEVERE THUNDERSTORM
WATCH UNTIL 1 AM CDT TUESDAY.
JHM

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 7:06 PM CDTTornado WarningMPXDakota24 min
Jul 20, 7:13 PM CDTTornado WarningMPXAnoka, Hennepin, Ramsey27 min
Jul 20, 7:14 PM CDTSevere Thunderstorm WarningMPXMeeker61 min
Jul 20, 8:00 PM CDTSevere Thunderstorm WarningMPXLac qui Parle60 min
Jul 20, 8:09 PM CDTSevere Thunderstorm WarningMPXRamsey, Washington51 min
Jul 20, 9:34 PM CDTSevere Thunderstorm WarningMPXHennepin, Scott56 min
Jul 20, 9:45 PM CDTSevere Thunderstorm WarningMPXKandiyohi, Meeker60 min

Nearby

Severe Thunderstorm Warnings in Minnesota, 1987Every severe thunderstorm warning in 1987

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.