Alert archive / California / Severe Thunderstorm Warnings in 2001
Severe Thunderstorm Warning 2, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this severe thunderstorm warning at Dec 20, 2001, 4:34 PM PST for Santa Clara County, Santa Cruz County, California. It was in force for 26 min. 1 report came from 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, with what was reported inside it.
The facts
- Issued
- Dec 20, 2001, 4:34 PM PST (00:34 UTC)
- Expired
- Dec 20, 2001, 5:00 PM PST
- In force
- 26 min
- Issued by
- NWS San Francisco Bay Area, CA
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
Counties Santa Clara County, CA, Santa Cruz County, CA
The radar
The San Francisco radar (KMUX), 21 km from the middle of the area, began a volume at 00:38 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
| Time | Report | Where | Remark |
|---|---|---|---|
| Dec 20, 4:45 PM PST | Tornado F1 | Watsonville Muni Arp, CA | A minor tornado was spawned from a line of convection across the Monterey bay that went ashore near Watsonville CA. The storm downed a power line by snapping off four poles, destroyed a green house and some trailers, then about a half a mile to the east tore t |
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 nearest sounding before it
Oakland, CA (KOAK), launched 00:00Z, 0.6 hours before the alert went out and 87 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.
- 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
The text
As transmitted, in the capitals the NWS used until 2016.
214 WUUS56 KMTR 210036 SVRSFO CAC085-087-210100- BULLETIN - EAS ACTIVATION REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE SAN FRANCISCO CA 434 PM PST THU DEC 20 2001 THE NATIONAL WEATHER SERVICE IN SAN FRANCISCO BAY AREA HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... CENTRAL SANTA CLARA COUNTY IN WESTERN CALIFORNIA THIS INCLUDES THE CITIES OF...MORGAN HILL...GILROY SOUTHEASTERN SANTA CRUZ COUNTY IN WESTERN CALIFORNIA * UNTIL 500 PM PST * AT 426 PM PST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 3 MILES NORTH OF WATSONVILLE...MOVING NORTHEAST AT 20 MPH. * THE SEVERE THUNDERSTORM WILL BE NEAR... 5 MILES NORTHWEST OF GILROY AT 450 PM PST 4 MILES SOUTHEAST OF MORGAN HILL AT 500 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 3699 12189 3691 12177 3710 12138 3726 12158
The office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 20, 5:00 PM PST | Severe Thunderstorm Warning | MTR | Santa Clara | 15 min |
| Dec 20, 7:00 PM PST | Severe Thunderstorm Warning | MTR | Santa Clara, Santa Cruz | 30 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.