Alert archive / California / Flash Flood Warnings in 2012

Flash Flood Warning 1, NWS San Francisco Bay Area, CA

November 30, 2012Sonoma County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Nov 30, 2012, 4:16 AM PST for Sonoma County, California. It was in force for 119 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Nov 30, 2012, 4:16 AM PST (12:16 UTC)
Expired
Nov 30, 2012, 6:15 AM PST
In force
119 min
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

County Sonoma County, CA

The radar

The Sacramento radar (KDAX), 86 km from the middle of the area, began a volume at 12:16 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, 0.3 hours before the alert went out and 70 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 2012-11-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 60 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 2012-11-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 462 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
60 J/kg
Mixed-layer CIN
-60 J/kg
Mixed-layer LCL
551 m above ground
0-6 km bulk shear
67 kt
0-1 km storm-relative helicity
462 m²/s²
0-3 km storm-relative helicity
616 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

The text

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

189 
WGUS56 KMTR 301216
FFWMTR
CAC097-301415-
/O.NEW.KMTR.FF.W.0001.121130T1216Z-121130T1415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
416 AM PST FRI NOV 30 2012

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

* FLASH FLOOD WARNING FOR...
  SONOMA COUNTY IN WESTERN CALIFORNIA...
  THIS INCLUDES THE CITY OF PETALUMA...

* UNTIL 615 AM PST.

* AT 406 AM PST...AUTOMATED RAIN GAGES INDICATED THAT PENNGROVE   
STREAM IN PETALUMA HAS EXCEEDED FLOOD STAGE AND CONTINUES TO RISE. 
IN ADDITION...NWS DOPPLER RADAR ALSO INDICATED ANOTHER BAND OF LIGHT 
TO MODERATE PRECIPITATION MOVING OVER THE REGION. 

A FLASH FLOOD WARNING MEANS THAT FLOODING IS OCCURRING OR IS
IMMINENT.

RUNOFF FROM HEAVY RAINFALL WILL CAUSE LOCALIZED FLOODING OF SMALL
CREEKS AND STREAMS AS WELL AS ROADWAYS...UNDERPASSES AND OTHER LOW
LYING SPOTS. DO NOT ATTEMPT TO CROSS SWIFTLY FLOWING WATER OR WATER
OF UNKNOWN DEPTH. TURN AROUND...DONT DROWN.

IT IS IMPORTANT FOR CAMPERS AND HIKERS TO KNOW WHERE THEY ARE
RELATIVE TO CREEKS...STREAMS...OR RIVERS WHICH CAN BECOME DANGEROUS
IN HEAVY RAINS. BE PARTICULARLY AWARE IN HILLY TERRAIN WHERE MANY LOW
WATER CROSSINGS CAN QUICKLY BECOME KILLERS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE.

LAT...LON 3832 12269 3830 12250 3818 12252 3821 12270

$$

RILEY/STROBIN
1 follow-up statement
237 
WGUS76 KMTR 301414
FFSMTR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
614 AM PST FRI NOV 30 2012

CAC097-301424-
/O.EXP.KMTR.FF.W.0001.000000T0000Z-121130T1415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SONOMA CA-
614 AM PST FRI NOV 30 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 615 AM PST FOR SONOMA
COUNTY...

ADDITIONAL WARNINGS WILL BE ISSUED.

LAT...LON 3832 12269 3830 12250 3818 12252 3821 12270

$$

JOHNSON

The office that day

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

IssuedProductOfficeCountiesLasted
Nov 30, 5:38 AM PSTAreal Flood AdvisoryMTRSanta Cruz6 hr
Nov 30, 6:22 AM PSTFlash Flood WarningMTRSonoma3 hr
Nov 30, 8:27 AM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, Marin, Monterey, San Benito, City and County of San Francisco and 3 more3 hr
Nov 30, 9:02 AM PSTAreal Flood AdvisoryMTRMarin, Napa, Sonoma118 min
Nov 30, 9:29 AM PSTFlash Flood WarningMTRMonterey61 min
Nov 30, 10:38 AM PSTFlash Flood WarningMTRMonterey82 min
Nov 30, 11:03 AM PSTRiver Flood WatchMTRSonoma26 days
Nov 30, 11:25 AM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, Marin, Monterey, San Benito, City and County of San Francisco and 3 more3 hr
Nov 30, 11:59 AM PSTFlash Flood WarningMTRMonterey3 hr
Nov 30, 2:56 PM PSTSmall Craft AdvisoryMTR47 hr

Nearby

Flash Flood Warnings in California, 2012Every flash flood 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.