Alert archive / Utah / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 117, NWS Salt Lake City, UT

September 21, 1997San Juan County, Utah

NWS Salt Lake City, UT issued this severe thunderstorm warning at Sep 21, 1997, 12:20 PM MDT for San Juan County, Utah. It was in force for 60 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
Sep 21, 1997, 12:20 PM MDT (18:20 UTC)
Expired
Sep 21, 1997, 1:20 PM MDT
In force
60 min
Issued by
NWS Salt Lake City, UT
Area
Whole counties

County San Juan County, UT

The radar

The Grand Junction radar (KGJX), 212 km from the middle of the area, began a volume at 18:23 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

Grand Junction, CO (KGJT), launched 12:00Z, 6.3 hours before the alert went out and 202 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, Grand Junction, CO at 12:00Z on 1997-09-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 67 joules per kilogram.LCLLFCEL10008507005003002001001 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, Grand Junction, CO at 12:00Z on 1997-09-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 90 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
67 J/kg
Mixed-layer CIN
-120 J/kg
Mixed-layer LCL
925 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
90 m²/s²
0-3 km storm-relative helicity
245 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

Open this sounding in Storm Lab

The text

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

543 
WUUS1 KSLC 211822 RRA
SVRSLC
UTC037-211920-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1220 PM MDT SUN SEP 21 1997

THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY UT HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 120 PM MDT
FOR PEOPLE IN THE FOLLOWING LOCATION...

IN SOUTHEASTERN UTAH

   ...SOUTH CENTRAL AND EASTERN SAN JUAN COUNTY
 
AT 1218 PM MDT...A SEVERE THUNDERSTORM WITH 3/4 INCH DIAMETER
HAIL AND HEAVY RAIN WAS REPORTED BY A SPOTTER 20 MILES SOUTH OF
BLANDING MOVING NORTHEAST AT 30 MPH.

THIS STORM CAN BE EXPECTED IN THE VICINITY OF...
BLANDING               AT AROUND 1245 PM MDT
 
THIS THUNDERSTORM WILL PRODUCE STRONG GUSTY WINDS...LARGE
HAIL...AND FREQUENT LIGHTNING.  TAKE COVER WHEN THREATENING WEATHER
APPROACHES.

ERC...1820Z
&

The office that day

Everything else NWS Salt Lake City, UT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 21, 3:39 PM MDTSevere Thunderstorm WarningSLCSan Juan46 min

Nearby

Severe Thunderstorm Warnings in Utah, 1997Every severe thunderstorm warning in 1997

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.