Alert archive / California / Flash Flood Warnings in 2012

Flash Flood Warning 16, NWS San Francisco Bay Area, CA

December 23, 2012Santa Cruz County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Dec 23, 2012, 7:01 PM PST for Santa Cruz County, California. It was in force for 108 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
Dec 23, 2012, 7:01 PM PST (03:01 UTC)
Expired
Dec 23, 2012, 8:49 PM PST
In force
108 min
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

County Santa Cruz County, CA

The radar

The San Francisco radar (KMUX), 27 km from the middle of the area, began a volume at 03:01 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 00:00Z, 3.0 hours before the alert went out and 97 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 00:00Z on 2012-12-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 6 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 00:00Z on 2012-12-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 252 square meters per square second.19395878Sfc1 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
6 J/kg
Mixed-layer CIN
-11 J/kg
Mixed-layer LCL
487 m above ground
0-6 km bulk shear
69 kt
0-1 km storm-relative helicity
252 m²/s²
0-3 km storm-relative helicity
284 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

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

066 
WGUS56 KMTR 240301
FFWMTR
CAC087-240500-
/O.NEW.KMTR.FF.W.0016.121224T0301Z-121224T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
701 PM PST SUN DEC 23 2012

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

* FLASH FLOOD WARNING FOR...
  SANTA CRUZ COUNTY IN WESTERN CALIFORNIA...
  THIS INCLUDES THE CITY OF WATSONVILLE...

* UNTIL 900 PM PST.

* AT 640 PM PST THE STREAM GAGE ON THE CORRALITOS CREEK AT FREEDOM   
  INDICATED THE CORRALITOS CREEK HAD REACHED FLOOD STAGE AND WAS     
  CONTINUING TO RISE. IN ADDITION...NATIONAL WEATHER SERVICE DOPPLER 
  RADAR AND AUTOMATED RAIN GAGES INDICATED THAT MODERATE RAIN WAS    
  CONTINUING ACROSS THE BASIN. 

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO INTERLAKEN
  AND FREEDOM

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 3693 12180 3697 12182 3696 12172 3692 12174
      3688 12180 3689 12182

$$

DYKEMA
1 follow-up statement
598 
WGUS76 KMTR 240449
FFSMTR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
849 PM PST SUN DEC 23 2012

CAC087-240458-
/O.CAN.KMTR.FF.W.0016.000000T0000Z-121224T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SANTA CRUZ CA-
849 PM PST SUN DEC 23 2012

...THE FLASH FLOOD WARNING FOR THE CORRALITOS CREEK IN SANTA CRUZ 
COUNTY HAS BEEN CANCELLED...

AT 830 PM PST THE STREAM GAGE ON THE CORRALITOS CREEK AT FREEDOM 
INDICATED THAT THE CREEK HAD FALLEN BELOW FLOOD STAGE AND WAS 
CONTINUING TO RECEDE.  IN ADDITION...MOST OR THE SIGNIFICANT 
RAINFALL HAS MOVED TO THE SOUTH AND EAST OF SANTA CRUZ COUNTY AND 
LITTLE ADDITIONAL RAINFALL IS EXPECTED FOR THE REMAINDER OF THE 
EVENING.

MINOR FLOODING WILL CONTINUE ACROSS SAN MATEO AND SANTA CRUZ COUNTY 
FOR THE REMAINDER OF THE EVENING AS RUNOFF FROM HEAVY RAIN TODAY 
SLOWLY RECEDES. IN ADDITION...SHALLOW LANDSLIDES AND DEBRIS FLOWS 
MAY OCCUR IN AREAS OF STEEP TERRAIN FOR SEVERAL HOURS AFTER RAINFALL 
HAS ENDED.

LAT...LON 3693 12180 3697 12182 3696 12172 3692 12174
      3688 12180 3689 12182

$$

DYKEMA

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 23, 4:04 PM PSTAreal Flood AdvisoryMTRAlameda, San Mateo, Santa Clara, Santa Cruz3 hr
Dec 23, 4:43 PM PSTFlash Flood WarningMTRSanta Cruz2 hr
Dec 23, 5:05 PM PSTFlash Flood WarningMTRSan Mateo, Santa Cruz115 min
Dec 23, 7:04 PM PSTFlash Flood WarningMTRSan Mateo, Santa Cruz86 min
Dec 23, 7:30 PM PSTAreal Flood WarningMTRSan Mateo, Santa Clara105 min
Dec 23, 8:11 PM PSTAreal Flood AdvisoryMTRMonterey, San Benito, Santa Clara, Santa Cruz94 min
Dec 24, 2:41 PM PSTSmall Craft AdvisoryMTR3 days

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.