Alert archive / Utah / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 9, NWS Salt Lake City, UT

July 21, 1987Grand County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Jul 21, 1987, 6:29 PM MDT for Grand County, Utah. It was in force for 46 min.

The area

The counties it named.

The facts

Issued: Jul 21, 1987, 6:29 PM MDT (00:29 UTC)
Expired: Jul 21, 1987, 7:15 PM MDT
In force: 46 min
Issued by: NWS Salt Lake City, UT
Area: Whole counties

County Grand County, UT

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

Grand Junction, CO (KGJT), launched 00:00Z, 0.5 hours before the alert went out and 94 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: 1343 J/kg
Mixed-layer CIN: -38 J/kg
Mixed-layer LCL: 2581 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 90 m²/s²
0-3 km storm-relative helicity: 150 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 6.2

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KSLC 220029
SVRSLC
UTC019-220115-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
629 PM MDT TUE JUL 21 1987
 
THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM WARNING
EFFECTIVE UNTIL  715 PM MDT FOR PEOPLE IN THE FOLLOWING COUNTY...
 
IN EAST CENTRAL UTAH
          ...WESTERN GRAND
 
RADAR INDICATES THAT THE HEAVY THUNDERSTORM THAT MOVED THROUGH
EASTERN EMERY COUNTY HAD MOVED INTO WESTERN GRAND COUNTY AT 630 PM
MDT. THIS STORM CONTINUES TO BE VERY INTENSE ON RADAR AS IT MOVES
RAPIDLY TO THE NORTEAST.
 
IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER FROM THE WEATHER IN A
STRONG BUILDING.  DAMAGING WIND...LARGE HAIL...VERY HEAVY RAIN...
AND DEADLY LIGHTNING ARE ALL POSSIBLE IN SEVERE THUNDERSTORMS.
STAY INSIDE AWAY FROM WINDOWS UNTIL THE STORM HAS PASSED.

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 21, 4:35 PM MDT, 1 hour 54 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY
430 PM MDT TUE JUL 21 1987

          ...STILL SCATTERED THUNDERSTORMS OVER THE STATE...

SCATTERED THUNDERSTORMS WILL CONTINUE OVER UTAH THIS EVENING. A FEW
OF THE CELLS STILL ARE PRODUCING LOCAL HEAVY RAIN..STRONG WINDS AND
HAIL. ANOTHER HIT THE PROVO/OREM AREA ABOUT 315 PM WITH 1/2 INCH
HAIL. SNOWBIRD HAS HAD WIND GUSTS TO 40 MPH WITH THUNDERSTORMS AND SMALL
HAIL. A SMALL ROCKSLIDE WAS REPORTED TO HAVE CLOSED THE ROAD UP
LITTLE COTTONWOOD CANYON. ONE INCH DIAMETER HAIL HIT KAMAS BETWEEN
2 AND 3 PM AND GUNNISON AND CENTERFIELD IN THE SEVIER VALLEY WERE HARD
HIT WITH GOLFBALL SIZED HAIL AT 330 PM WHILE MANTI AND EPHRIAM HAD
CHERRY SIZED HAIL A FEW MINUTES LATER.  TREES AND POWER LINES WERE
REPORTED DOWN ALONG WITH MUD SLIDES AROUND HOYTSVILLE IN WEST SUMMIT
COUNTY FROM EARLIER THUNDERSTORMS. 1.50 INCHES OF RAIN FELL AT
CROYDON IN 2 HOURS AND 1 INCH AT KAMAS IN A FEW MINUTES. COALVILLE
ESTIMATED HAIL JUST SMALLER THAN A BASEBALL AROUND 130 PM.

BESIDES ALL THE THUNDERSTORM ACTIVITY...STRONG GUSTY SOUTH WINDS
ARE BLOWING IN THE SOUTHWEST DESERT AREAS. MILFORD REPORTS A
GUSTS TO 47 MPH AND MANY OTHER STATIONS GUSTS TO BETWEEN 30 AND 40 MPH.
THESE WINDS SHOULD DECREASE SLOWLY DURING THE EVENING.

THE THUNDERSTORMS ARE EXPECTED TO DECREASE BY ABOUT MIDNIGHT AS
SOMEWHAT DRIER AIR MOVES IN OVER THE STATE FROM THE SOUTHWEST. THE
FORECAST FOR WEDNESDAY IS FOR WIDE^LY SCATTERED THUNDERSTORMS MAINLY
NEAR THE NORTHERN MOUNTAINS... MUCH LESS ACTIVITY THEN TODAY.

FURTHER STATEMENTS WILL BE ISSUED AS NECESSARY.

DJ...2225Z

Nearby

Severe Thunderstorm Warnings in Utah, 1987 Every 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.