Alert archive / Utah / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 21, NWS Grand Junction, CO

September 20, 1997Grand County, Utah

NWS Grand Junction, CO issued this severe thunderstorm warning at Sep 20, 1997, 2:27 PM MDT for Grand County, Utah. It was in force for 48 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Sep 20, 1997, 2:27 PM MDT (20:27 UTC)
Expired
Sep 20, 1997, 3:15 PM MDT
In force
48 min
Issued by
NWS Grand Junction, CO
Area
Whole counties

County Grand County, UT

The radar

The Grand Junction radar (KGJX), 118 km from the middle of the area, began a volume at 20:29 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
Sep 20, 3:00 PM MDTHail 1.75Crescent Jct, UT

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

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

IssuedProductOfficeLasted
Sep 20, 2:00 PM MDTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Grand Junction, CO (KGJT), launched 12:00Z, 8.5 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-pSkew-T log-p diagram, Grand Junction, CO at 12:00Z on 1997-09-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 197 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 1997-09-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 121 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
197 J/kg
Mixed-layer CIN
-94 J/kg
Mixed-layer LCL
696 m above ground
0-6 km bulk shear
64 kt
0-1 km storm-relative helicity
121 m²/s²
0-3 km storm-relative helicity
209 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.6

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KGJT 202024 RRA
SVRGJT
UTC019-202115-

BULLETIN - EAS ACTIVATION/IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
227 PM MDT SAT SEP 20 1997

* SEVERE THUNDERSTORM WARNING FOR
  WEST CENTRAL GRAND COUNTY UTAH - EAST CENTRAL UTAH

* UNTIL 315 PM MDT
 
* SOME LOCATIONS AFFECTED
  GREEN RIVER UTAH

* AT 225PM RADAR INDICATED A SEVERE THUNDERSTORM 15 SOUTH GREEN RIVER
MOVING NE AT 30 MPH.

* THE STORM IS EXPECTED TO BE EAST GREEN RIVER ACROSS I70 AT 240PM.

THIS IS A DANGEROUS STORM...POSSIBLY WITH LARGE HAIL AND DAMAGING
WINDS...DO NOT GO OUTDOORS IF THIS STORM APPROACHES YOUR AREA.

JACOBSON

The office that day

Everything else NWS Grand Junction, CO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 20, 1:31 PM MDTSevere Thunderstorm WarningGJTUintah34 min
Sep 20, 3:18 PM MDTSevere Thunderstorm WarningGJTGrand62 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.