Alert archive / California / Flash Flood Warnings in 2014

Flash Flood Warning 9, NWS San Francisco Bay Area, CA

December 11, 20144 counties in California

NWS San Francisco Bay Area, CA issued this flash flood warning at Dec 11, 2014, 9:22 AM PST for 4 counties in California. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Dec 11, 2014, 9:22 AM PST (17:22 UTC)
Expired
Dec 11, 2014, 12:15 PM PST
In force
3 hr
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

Counties Alameda County, CA, Contra Costa County, CA, Santa Clara County, CA, Santa Cruz County, CA

The radar

The San Francisco radar (KMUX), 63 km from the middle of the area, began a volume at 17:26 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, 5.4 hours before the alert went out and 35 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 2014-12-11Temperature 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, Oakland, CA at 12:00Z on 2014-12-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 308 square meters per square second.1939587897117Sfc1 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
893 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
308 m²/s²
0-3 km storm-relative helicity
555 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.

348 
WGUS56 KMTR 111722
FFWMTR
CAC001-013-085-087-112015-
/O.NEW.KMTR.FF.W.0009.141211T1722Z-141211T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
922 AM PST THU DEC 11 2014

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

* FLASH FLOOD WARNING FOR FLASH FLOODING AND DEBRIS FLOWS FOR...
  ALAMEDA COUNTY IN NORTHERN CALIFORNIA...
  THIS INCLUDES THE CITIES OF...PLEASANTON...LIVERMORE...FREMONT...
  DUBLIN...
  CONTRA COSTA COUNTY IN NORTHERN CALIFORNIA...
  THIS INCLUDES THE CITIES OF...OAKLEY...ANTIOCH...
  SANTA CLARA COUNTY IN NORTHERN CALIFORNIA...
  THIS INCLUDES THE CITIES OF...SUNNYVALE...SARATOGA...SANTA CLARA...
  SAN JOSE...MILPITAS...LOS GATOS...CUPERTINO...CAMPBELL...
  SANTA CRUZ COUNTY IN NORTHERN CALIFORNIA...
  THIS INCLUDES THE CITY OF SANTA CRUZ...

* UNTIL 1215 PM PST

* AT 918 AM PST...THE PUBLIC REPORTED HEAVY RAIN AND 
FLOODING...FROM   AN AREA OF HEAVY RAIN OVER THE WARNED AREA. 
WIDESPREAD FLASH FLOODING HAS OCCURRED ACROSS PORTIONS OF THE BAY 
AREA WITH THE PASSING OF THIS HEAVY RAIN. TRAVEL IS NOT RECCOMENDED 
DURING THE NEXT FEW HOURS IN THE FLASH FLOOD WARNING AREA.  

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO DISCOVERY
  BAY...BRENTWOOD AND BLACKHAWK

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE SUBJECT TO FLOODING.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 3810 12157 3797 12156 3696 12186 3697 12194
      3694 12207 3699 12219 3738 12204 3804 12186
      3805 12184 3802 12181 3802 12174 3806 12169
      3810 12168 3811 12160
TIME...MOT...LOC 1721Z 180DEG 0KT 3747 12192

$$

JOHNSON

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 11, 3:31 AM PSTAreal Flood AdvisoryMTRMarin, Napa, Sonoma8 hr
Dec 11, 6:50 AM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, Marin, City and County of San Francisco, San Mateo3 hr
Dec 11, 7:15 AM PSTFlash Flood WarningMTRMarin, Sonoma3 hr
Dec 11, 7:48 AM PSTFlash Flood WarningMTRNapa, Sonoma3 hr
Dec 11, 8:00 AM PSTFlash Flood WarningMTRCity and County of San Francisco, San Mateo90 min
Dec 11, 8:16 AM PSTFlash Flood WarningMTRAlameda, Contra Costa, San Mateo, Santa Clara, Santa Cruz3 hr
Dec 11, 8:45 AM PSTSmall Craft Advisory for Hazardous SeasMTR31 hr
Dec 11, 9:00 AM PSTFlash Flood WarningMTRNapa, Sonoma7 hr
Dec 11, 9:24 AM PSTRiver Flood WarningMTRNapa20 hr
Dec 11, 9:24 AM PSTRiver Flood WarningMTRSonoma53 hr
Dec 11, 10:15 AM PSTFlash Flood WarningMTRMarin, Napa, Sonoma90 min
Dec 11, 10:41 AM PSTCoastal Flood WarningMTRAlameda, Contra Costa, City and County of San Francisco, San Mateo, Santa Clara8 hr
Dec 11, 10:42 AM PSTFlash Flood WarningMTRMonterey, Santa Clara, Santa Cruz3 hr
Dec 11, 10:43 AM PSTFlash Flood WarningMTRNapa, Sonoma92 min
Dec 11, 11:22 AM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, City and County of San Francisco, San Mateo, Santa Clara, Santa Cruz3 hr
Dec 11, 11:46 AM PSTAreal Flood AdvisoryMTRMonterey3 hr
Dec 11, 12:00 PM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, Santa Clara, Santa Cruz3 hr
Dec 11, 1:52 PM PSTAreal Flood AdvisoryMTRMarin, Napa, Sonoma5 hr
Dec 11, 2:21 PM PSTFlash Flood WarningMTRSan Mateo, Santa Clara, Santa Cruz54 min
Dec 11, 2:23 PM PSTFlash Flood WarningMTRMonterey3 hr
Dec 11, 2:59 PM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, City and County of San Francisco, San Mateo, Santa Clara3 hr
Dec 11, 3:11 PM PSTAreal Flood AdvisoryMTRSan Mateo, Santa Clara, Santa Cruz3 hr

Nearby

Flash Flood Warnings in California, 2014Every flash flood warning in 2014

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.