Alert archive / California / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 21, NWS Las Vegas, NV

September 12, 1999San Bernardino County, California

NWS Las Vegas, NV issued this severe thunderstorm warning at Sep 12, 1999, 6:17 PM PDT for San Bernardino County, California. It was in force for 58 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties.

The facts

Issued
Sep 12, 1999, 6:17 PM PDT (01:17 UTC)
Expired
Sep 12, 1999, 7:15 PM PDT
In force
58 min
Issued by
NWS Las Vegas, NV
Area
Whole counties; the outline is the Mesonet’s reconstruction

County San Bernardino County, CA

The nearest sounding before it

San Diego, CA (KNKX), launched 00:00Z, 1.3 hours before the alert went out and 231 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, San Diego, CA at 00:00Z on 1999-09-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, San Diego, CA at 00:00Z on 1999-09-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 12 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2100 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
12 m²/s²
0-3 km storm-relative helicity
55 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.

000 
TTAA00 KVEF 130120 RRA
SVRLAS
CAC071-130215-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE LAS VEGAS NV
617 PM PDT SUN SEP 12 1999

THE NATIONAL WEATHER SERVICE IN LAS VEGAS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN SAN BERNARDINO COUNTY IN SOUTHEAST CALIFORNIA

* UNTIL 715 PM PDT

* AT 617 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM OVER SOUTH CENTRAL SAN BERNARDINO 
COUNTY...OR   ABOUT 27 MILES SOUTHEAST OF AMBOY...MOVING SOUTHEAST 
AT 15 MPH. THE STORM WILL BE NEAR STATE HIGHWAY 62 NORTHEAST OF 
CLARKS PASS BETWEEN 645 AND 700 PM PDT.

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH YOU SHOULD PREPARE
FOR DAMAGING WINDS IN EXCESS OF 60 MPH...LARGE HAIL...AND DEADLY
LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO SHELTER...PREFERABLY INSIDE
A STRONG BUILDING BUT AWAY FROM WINDOWS.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAPY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE IN LAS VEGAS.

LAT...LON 3435 11553 3419 11563 3394 11514 3418 11500

SKRBAC

The office that day

Everything else NWS Las Vegas, NV issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 12, 5:12 PM PDTSevere Thunderstorm WarningVEFSan Bernardino63 min
Sep 12, 8:45 PM PDTSevere Thunderstorm WarningVEFInyo60 min
Sep 12, 8:45 PM PDTSevere Thunderstorm WarningVEFSan Bernardino60 min
Sep 12, 8:50 PM PDTFlash Flood WarningVEFSan Bernardino3 hr
Sep 12, 8:50 PM PDTFlash Flood WarningVEFInyo3 hr
Sep 12, 9:44 PM PDTSevere Thunderstorm WarningVEFSan Bernardino61 min

Nearby

Severe Thunderstorm Warnings in California, 1999Every severe thunderstorm warning in 1999

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.