Alert archive / California / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 3, NWS San Francisco Bay Area, CA

December 20, 2001Santa Clara County, California

NWS San Francisco Bay Area, CA issued this severe thunderstorm warning at Dec 20, 2001, 5:00 PM PST for Santa Clara County, California. It was in force for 15 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
Dec 20, 2001, 5:00 PM PST (01:00 UTC)
Expired
Dec 20, 2001, 5:15 PM PST
In force
15 min
Issued by
NWS San Francisco Bay Area, CA
Area
Whole counties; the outline is the Mesonet’s reconstruction

County Santa Clara County, CA

The radar

The San Francisco radar (KMUX), 30 km from the middle of the area, began a volume at 01:01 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

Oakland, CA (KOAK), launched 00:00Z, 1.0 hours before the alert went out and 90 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, Oakland, CA at 00:00Z on 2001-12-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 26 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, Oakland, CA at 00:00Z on 2001-12-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 106 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
26 J/kg
Mixed-layer CIN
-83 J/kg
Mixed-layer LCL
814 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
106 m²/s²
0-3 km storm-relative helicity
152 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

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

023 
WUUS56 KMTR 210100
SVRSFO
CAC085-210130-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
500 PM PST THU DEC 20 2001

THE NATIONAL WEATHER SERVICE IN SAN FRANCISCO BAY AREA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN SANTA CLARA COUNTY IN WESTERN CALIFORNIA
  THIS INCLUDES THE CITIES OF...MORGAN HILL...GILROY

* UNTIL 515 PM PST

* AT 500 PM PST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM BETWEEN GILROY AND MORGAN HILL...OR ABOUT 3 
  MILES NORTHWEST OF GILROY...MOVING NORTHEAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
RURAL EASTERN SANTA CLARA COUNTY AT 515 PM PST

VERY LARGE HAIL IS POSSIBLE WITH THIS SEVERE THUNDERSTORM. IF YOU ARE
IN THE PATH OF THE STORM...PUT YOUR CAR IN A GARAGE AND MOVE TO A
SUBSTANTIAL SHELTER.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE IN SAN FRANCISCO BAY AREA.

LAT...LON 3704 12177 3692 12161 3716 12126 3732 12146

The office that day

Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Dec 20, 4:34 PM PSTSevere Thunderstorm WarningMTRSanta Clara, Santa Cruz26 min
Dec 20, 7:00 PM PSTSevere Thunderstorm WarningMTRSanta Clara, Santa Cruz30 min

Nearby

Severe Thunderstorm Warnings in California, 2001Every severe thunderstorm warning in 2001

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.