Alert archive / California / Severe Thunderstorm Warnings in 2010

Severe Thunderstorm Warning 1, NWS San Francisco Bay Area, CA

January 18, 2010Santa Clara County, Santa Cruz County, California

NWS San Francisco Bay Area, CA issued this severe thunderstorm warning at Jan 18, 2010, 11:02 AM PST for Santa Clara County, Santa Cruz County, California. It was in force for 43 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Jan 18, 2010, 11:02 AM PST (19:02 UTC)
Expired
Jan 18, 2010, 11:45 AM PST
In force
43 min
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon

Counties Santa Clara County, CA, Santa Cruz County, CA

The radar

The San Francisco radar (KMUX), 5 km from the middle of the area, began a volume at 19:02 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 12:00Z, 7.0 hours before the alert went out and 74 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 12:00Z on 2010-01-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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 12:00Z on 2010-01-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 133 square meters per square second.1939587897Sfc1 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
777 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
133 m²/s²
0-3 km storm-relative helicity
132 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS San Francisco Bay Area, CA wrote its last area forecast discussion before this severe thunderstorm warning went out at Jan 18, 8:25 AM PST, 2 hours 37 minutes earlier.

Area forecast discussion, Jan 18, 8:25 AM PST, 2 hours 37 minutes before
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Hazardous weather outlook, Jan 18, 4:45 AM PST, 6 hours 17 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
445 AM PST MON JAN 18 2010

CAZ006-505-190000-
SAN FRANCISCO-
COASTAL NORTH BAY...INCLUDING POINT REYES NATIONAL SEASHORE-
445 AM PST MON JAN 18 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR COASTAL SECTIONS OF
SONOMA AND MARIN COUNTIES AS WELL AS FOR SAN FRANCISCO COUNTY.

.DAY ONE...MONDAY AND MONDAY NIGHT

RAIN...WIND AND BUILDING SEAS WILL EFFECT THE COAST TODAY.
A HIGH SURF ADVISORY AND WIND ADVISORY GO INTO EFFECT TODAY.
IN ADDITION PERIODS OF RAIN...POSSIBLY HEAVY AT TIMES MAY CAUSE
LOCAL FLOODING.

*  WIND ADVISORY.....SEE SFONPWMTR WWUS76 KMTR FOR DETAILS  *
*  HIGH SURF ADVISORY....SEE SFOCFWMTR WHUS46 KMTR FOR DETAILS *
*  HYDROLOGIC OUTLOOK....SEE SFOESFMTR FGUS76 KMTR FOR DETAILS  *

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A SERIES OF POWERFUL WINTER STORMS WILL BRING PERIODS OF HEAVY
RAIN...STRONG WINDS...AND LARGE OCEAN WAVES TO THE REGION FROM
TUESDAY THROUGH THURSDAY. PERIODS OF HEAVY RAIN THIS WEEK MAY RESULT
IN LOCAL FLOODING. VERY LARGE OCEAN SWELLS ARE FORECAST TO IMPACT THE
COAST THROUGH THURSDAY. A HIGH SURF WARNING WILL GO INTO EFFECT AT
4 AM TUESDAY FOR SEAS IN EXCESS OF 20 FEET ALONG THE COAST.

*  HIGH SURF WARNING....SEE SFOCFWMTR WHUS46 KMTR FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS PER STANDARD OPERATING PROCEDURES.

CAZ509-529-530-190000-
SAN FRANCISCO PENINSULA COAST-
SOUTHERN MONTEREY BAY AND BIG SUR COAST-NORTHERN MONTEREY BAY-
445 AM PST MON JAN 18 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR COASTAL SECTIONS OF SAN
MATEO...SANTA CRUZ...AND MONTEREY COUNTIES.

.DAY ONE...MONDAY AND MONDAY NIGHT

RAIN...WIND AND BUILDING SEAS WILL EFFECT THE COAST TODAY.
A HIGH SURF ADVISORY AND HIGH WIND WARNING GO INTO EFFECT TODAY.
IN ADDITION PERIODS OF RAIN...POSSIBLY HEAVY AT TIMES MAY CAUSE
LOCAL FLOODING.

*  HIGH WIND WARNING.....SEE SFONPWMTR WWUS76 KMTR FOR DETAILS *
*  HIGH SURF ADVISORY....SEE SFOCFWMTR WHUS46 KMTR FOR DETAILS *
*  HYDROLOGIC OUTLOOK....SEE SFOESFMTR FGUS76 KMTR FOR DETAILS *

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A SERIES OF POWERFUL WINTER STORMS WILL BRING PERIODS OF HEAVY
RAIN...STRONG WINDS...AND LARGE OCEAN WAVES TO THE REGION FROM
TUESDAY THROUGH THURSDAY. PERIODS OF HEAVY RAIN THIS WEEK MAY RESULT
IN LOCAL FLOODING. VERY LARGE OCEAN SWELL ARE FORECAST TO IMPACT THE
COAST THROUGH THURSDAY. A HIGH SURF WARNING GOES INTO EFFECT
BEGINNING AT 4 AM TUESDAY FOR SEAS IN EXCESS OF 20 FEET.

*  HIGH SURF WARNING....SEE SFOCFWMTR WHUS46 KMTR FOR DETAILS *

CAZ507-508-511>513-516>518-528-190000-
SOUTHERN SALINAS VALLEY...ARROYO SECO...AND LAKE SAN ANTONIO-
SANTA LUCIA MOUNTAINS AND LOS PADRES NATIONAL FOREST-
MOUNTAINS OF SAN BENITO COUNTY AND INTERIOR MONTEREY COUNTY
INCLUDING PINNACLES NATIONAL MONUMENT-NORTH BAY MOUNTAINS-
SAN FRANCISCO BAY SHORELINE-EAST BAY HILLS AND THE DIABLO RANGE-
NORTHERN SALINAS VALLEY...HOLLISTER VALLEY...AND CARMEL VALLEY-
SANTA CRUZ MOUNTAINS-SANTA CLARA VALLEY...INCLUDING SAN JOSE-
445 AM PST MON JAN 18 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INLAND SECTIONS OF THE SAN
FRANCISCO BAY AREA AND MONTEREY BAY AREA...EXCEPT THE NORTH AND
EAST BAY VALLEYS.

.DAY ONE...MONDAY AND MONDAY NIGHT

PERIODS OF RAIN AND STRONG WINDS WILL CONTINUE TODAY. A WIND
ADVISORY IS IN EFFECT. LOCALIZED FLOODING WILL BE POSSIBLE DURING
PERIODS OF HEAVY RAIN.

*  WIND ADVISORY.....SEE SFONPWMTR WWUS76 KMTR FOR DETAILS  *
*  HYDROLOGIC OUTLOOK....SEE SFOESFMTR FGUS76 KMTR FOR DETAILS *

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A SERIES OF POWERFUL WINTER STORMS WILL BRING PERIODS OF HEAVY
RAIN AND STRONG WINDS TO THE REGION FROM TUESDAY THROUGH THURSDAY.
PERIODS OF HEAVY RAIN THIS WEEK MANY RESULT IN LOCAL FLOODING.
ADDITIONAL WIND ADVISORIES MAY BE NEEDED LATER THIS WEEK AS THE
STORMS MOVE ONSHORE. DOWNED TREE LIMBS AND POWER OUTAGES WILL BE
POSSIBLE THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS PER STANDARD OPERATING PROCEDURES.

CAZ506-510-190000-
NORTH BAY INTERIOR VALLEYS-EAST BAY INTERIOR VALLEYS-
445 AM PST MON JAN 18 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE NORTH BAY VALLEYS AND
THE EAST BAY VALLEYS.

.DAY ONE...MONDAY AND MONDAY NIGHT

PERIODS OF RAIN WILL CONTINUE TODAY INTO TONIGHT. LOCALIZED FLOODING
WILL BE POSSIBLE DURING PERIODS OF HEAVY RAIN. LOCALLY STRONG WINDS
ARE EXPECTED TODAY AS WELL WITH GUSTS BETWEEN 30 AND 40 MPH.

*  HYDROLOGIC OUTLOOK....SEE SFOESFMTR FGUS76 KMTR FOR DETAILS *

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A SERIES OF POWERFUL WINTER STORMS WILL BRING PERIODS OF HEAVY
RAIN AND STRONG WINDS TO THE REGION FROM TUESDAY THROUGH THURSDAY.
PERIODS OF HEAVY RAIN THIS WEEK MAY RESULT IN LOCAL FLOODING.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS PER STANDARD OPERATING PROCEDURES.

In the hours before

Special weather statement, Jan 18, 10:24 AM PST, 38 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1024 AM PST MON JAN 18 2010

CAZ508>513-529-530-181915-
EAST BAY HILLS AND THE DIABLO RANGE CA-EAST BAY INTERIOR VALLEYS
CA-NORTHERN MONTEREY BAY CA-SAN FRANCISCO BAY SHORELINE CA-SAN
FRANCISCO PENINSULA COAST CA-SANTA CLARA VALLEY INCLUDING SAN JOSE
CA-SANTA CRUZ MOUNTAINS CA-SOUTHERN MONTEREY BAY AND BIG SUR COAST
CA-
1024 AM PST MON JAN 18 2010

...SIGNIFICANT WEATHER ADVISORY FOR MONTEREY...SANTA CRUZ...SAN
MATEO...SANTA CLARA AND ALAMEDA COUNTIES UNTIL 1115 AM PST...

AT 1020 AM PST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM BOULDER CREEK TO
FELTON TO 8 MILES SOUTH OF TWIN LAKES TO 7 MILES NORTHWEST OF DEL
MONTE FOREST...AND MOVING NORTHEAST AT 40 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THESE STORMS...ALONG WITH HEAVY RAIN.

AREAS AFFECTED BY THESE STORMS INCLUDE...SARATOGA...CUPERTINO...LOS
GATOS...LOS ALTOS...PALO ALTO...CAMPBELL...MOUNTAIN VIEW...
SUNNYVALE...SANTA CLARA...CORRALITOS...SAN JOSE...NEWARK...
MILPITAS...WATSONVILLE...FREMONT...MORGAN HILL...GILROY...
PLEASANTON...TWIN LAKES AND OPAL CLIFFS.

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

IN ADDITION...THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR
LOCAL RADIO AND TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR
ADDITIONAL INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL
WEATHER SERVICE.

LAT...LON 3747 12210 3746 12204 3750 12207 3773 12187
      3746 12162 3730 12156 3697 12156 3678 12178
      3682 12178 3695 12188 3696 12191 3694 12206
      3698 12214 3724 12230
TIME...MOT...LOC 1824Z 219DEG 35KT 3718 12213 3704 12205
          3687 12199 3666 12203

CW

The office that day

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

IssuedProductOfficeCountiesLasted
Jan 17, 6:39 PM PSTHigh Surf AdvisoryMTRMarin, Monterey, City and County of San Francisco, San Mateo, Santa Cruz, Sonoma33 hr
Jan 17, 8:05 PM PSTHigh Wind WarningMTRMonterey, San Mateo, Santa Cruz19 hr
Jan 18, 2:46 AM PSTHigh Surf WarningMTRMarin, Monterey, City and County of San Francisco, San Mateo, Santa Cruz, Sonoma3 days
Jan 18, 3:00 AM PSTGale WarningMTR32 hr
Jan 18, 9:40 AM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, Marin, Monterey, Napa, City and County of San Francisco and 4 more3 hr
Jan 18, 9:54 AM PSTSpecial Marine WarningMTR21 min
Jan 18, 10:06 AM PSTSpecial Marine WarningMTR24 min
Jan 18, 10:24 AM PSTSpecial Marine WarningMTR30 min
Jan 18, 10:24 AM PSTSpecial Weather StatementMTRAlameda, Santa Clara, Santa Cruz51 min
Jan 18, 11:35 AM PSTSpecial Weather StatementMTR40 min
Jan 18, 2:31 PM PSTGale WarningMTR25 hr
Jan 18, 2:50 PM PSTWind AdvisoryMTRAlameda, Contra Costa, Marin, Monterey, San Benito, City and County of San Francisco and 4 more22 hr

Nearby

Severe Thunderstorm Warnings in California, 2010Every severe thunderstorm warning in 2010

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.