Alert archive / California / Severe Thunderstorm Warnings in 2012
Severe Thunderstorm Warning 1, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this severe thunderstorm warning at Apr 12, 2012, 8:14 PM PDT for San Mateo County, California. It was in force for 31 min. 1 report came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Apr 12, 2012, 8:14 PM PDT (03:14 UTC)
- Expired
- Apr 12, 2012, 8:45 PM PDT
- In force
- 31 min
- Issued by
- NWS San Francisco Bay Area, CA
- Area
- Storm-based polygon
County San Mateo County, CA
The radar
The San Francisco radar (KMUX), 69 km from the middle of the area, began a volume at 03:17 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 |
|---|---|---|---|
| Apr 12, 8:30 PM PDT | HAIL 0.5 | Pacifica, CA | HALF INCH HAIL IN PACIFICA. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Oakland, CA (KOAK), launched 00:00Z, 3.2 hours before the alert went out and 25 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1716 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- -21 m²/s²
- 0-3 km storm-relative helicity
- 37 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
810
WUUS56 KMTR 130314
SVRMTR
CAC081-130345-
/O.NEW.KMTR.SV.W.0001.120413T0314Z-120413T0345Z/
BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
814 PM PDT THU APR 12 2012
THE NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR...
NORTHERN SAN MATEO COUNTY IN WESTERN CALIFORNIA...
THIS INCLUDES THE CITIES OF...SOUTH SAN FRANCISCO...SAN BRUNO...
PACIFICA...MILLBRAE...DALY CITY...BURLINGAME...
* UNTIL 845 PM PDT
* AT 809 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL. THIS
STORM WAS LOCATED NEAR EL GRANADA...OR 7 MILES SOUTHWEST OF
PACIFICA...AND MOVING NORTHEAST AT 25 MPH.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. IF A
TORNADO IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A
STURDY STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.
&&
LAT...LON 3762 12250 3769 12251 3770 12238 3766 12236
3764 12237 3761 12235 3760 12235 3760 12231
3748 12246 3749 12250 3753 12253 3760 12253
TIME...MOT...LOC 0313Z 213DEG 26KT 3755 12250
$$
DYKEMA2 follow-up statements
509
WWUS56 KMTR 130331
SVSMTR
SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
831 PM PDT THU APR 12 2012
CAC081-130345-
/O.CON.KMTR.SV.W.0001.000000T0000Z-120413T0345Z/
SAN MATEO CA-
831 PM PDT THU APR 12 2012
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 845 PM PDT
FOR NORTHERN SAN MATEO COUNTY...
AT 825 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE
HAIL. THIS STORM WAS LOCATED NEAR SAN BRUNO...MOVING NORTHEAST AT 25
MPH. ALTHOUGH THE STORM HAS WEAKENED SLIGHTLY IN THE PAST FIVE
MINUTES...IT IS STILL CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING
WINDS. THE STORM WILL REACH SOUTH SAN FRANCISCO BY 8:35 PM PDT.
OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
COLMA...DALY CITY...SOUTH SAN FRANCISCO AND BRISBANE
LAT...LON 3762 12250 3769 12251 3770 12238 3766 12236
3764 12237 3761 12235 3760 12235 3760 12231
3748 12246 3749 12250 3753 12253 3760 12253
TIME...MOT...LOC 0328Z 213DEG 26KT 3764 12242
$$
DYKEMA267
WWUS56 KMTR 130346
SVSMTR
SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
846 PM PDT THU APR 12 2012
CAC081-130353-
/O.EXP.KMTR.SV.W.0001.000000T0000Z-120413T0345Z/
SAN MATEO CA-
846 PM PDT THU APR 12 2012
...THE SEVERE THUNDERSTORM WARNING FOR SAN MATEO COUNTY WILL EXPIRE
AT 845 PM PDT...
DOPPLER RADAR INDICATED THE THUNDERSTORM WEAKENED CONSIDERABLY AS
IT MOVED THROUGH SOUTH SAN FRANCISCO AND THERE IS NO LONGER A THREAT
OF SEVERE WEATHER FROM THIS STORM. THEREFORE...THE SEVERE
THUNDERSTORM WARNING HAS BEEN ALLOWED TO EXPIRE AT 8:45 PM PDT.
LAT...LON 3762 12250 3769 12251 3770 12238 3766 12236
3764 12237 3761 12235 3760 12235 3760 12231
3748 12246 3749 12250 3753 12253 3760 12253
TIME...MOT...LOC 0343Z 213DEG 26KT 3773 12234
$$
DYKEMAThe office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 12, 7:37 PM PDT | Special Marine Warning | MTR | 23 min | |
| Apr 12, 8:11 PM PDT | Special Marine Warning | MTR | 19 min | |
| Apr 13, 3:07 AM PDT | Small Craft Advisory for Rough Bar | MTR | 42 hr |
Nearby
Severe Thunderstorm Warnings in California, 2012Every severe thunderstorm warning in 2012
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.