Alert archive / California / Flash Flood Warnings in 2014

Flash Flood Warning 3, NWS San Francisco Bay Area, CA

February 28, 2014San Mateo County, Santa Clara County, Santa Cruz County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 28, 2014, 6:55 AM PST for San Mateo County, Santa Clara County, Santa Cruz County, California. It was in force for 35 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
Feb 28, 2014, 6:55 AM PST (14:55 UTC)
Expired
Feb 28, 2014, 7:30 AM PST
In force
35 min
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

Counties San Mateo County, CA, Santa Clara County, CA, Santa Cruz County, CA

The radar

The San Francisco radar (KMUX), 40 km from the middle of the area, began a volume at 14:56 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, 2.9 hours before the alert went out and 31 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 2014-02-28Temperature 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°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 12:00Z on 2014-02-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 69 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
522 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
69 m²/s²
0-3 km storm-relative helicity
106 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.

713 
WGUS56 KMTR 281455
FFWMTR
CAC081-085-087-281530-
/O.NEW.KMTR.FF.W.0003.140228T1455Z-140228T1530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
655 AM PST FRI FEB 28 2014

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

* FLASH FLOOD WARNING FOR...
  SAN MATEO COUNTY IN WESTERN CALIFORNIA...
  THIS INCLUDES THE CITIES OF...REDWOOD CITY...MENLO PARK...EAST PALO
  ALTO...
  SANTA CLARA COUNTY IN WESTERN CALIFORNIA...
  THIS INCLUDES THE CITIES OF...PALO ALTO...MOUNTAIN VIEW...LOS
  ALTOS...
  SANTA CRUZ COUNTY IN WESTERN CALIFORNIA...

* UNTIL 730 AM PST.

* AT 649 AM PST...NWS DOPPLER RADAR INDICATED AN AREA OF MODERATE TO 
HEAVY RAIN SOUTH OF HIGHWAY 35 OR 9 MILES SOUTHWEST OF 
CUPERTINO...MOVING NORTHEAST AT 25 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO LOS  
ALTOS HILLS...WOODSIDE...STANFORD...ATHERTON AND PORTIONS OF HIGHWAY 
35...HIGHWAY 101 AND INTERSTATE 280.

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 3755 12226 3752 12217 3751 12216 3751 12213
      3750 12212 3749 12212 3748 12211 3748 12208
      3746 12205 3719 12210 3721 12231

$$

MM
2 follow-up statements
316 
WGUS76 KMTR 281518
FFSMTR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
718 AM PST FRI FEB 28 2014

CAC081-085-087-281530-
/O.CON.KMTR.FF.W.0003.000000T0000Z-140228T1530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SANTA CLARA CA-SANTA CRUZ CA-SAN MATEO CA-
718 AM PST FRI FEB 28 2014

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 730 AM PST FOR SAN
MATEO...SANTA CRUZ AND SANTA CLARA COUNTIES...

AT 711 AM PST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED THE 
HEAVIEST RAINFALL HAS DIMINISHED AND EXITED THE AREA BUT EXCESSIVE 
RAINFALL RUN OFF MAY STILL PRODUCING FLASH FLOODING IN THE WARNED 
AREA.  

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 3755 12226 3752 12217 3751 12216 3751 12213
      3750 12212 3749 12212 3748 12211 3748 12208
      3746 12205 3719 12210 3721 12231

$$

MM
923 
WGUS76 KMTR 281528
FFSMTR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
728 AM PST FRI FEB 28 2014

CAC081-085-087-281532-
/O.EXP.KMTR.FF.W.0003.000000T0000Z-140228T1530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SANTA CLARA CA-SANTA CRUZ CA-SAN MATEO CA-
728 AM PST FRI FEB 28 2014

...THE FLASH FLOOD WARNING WILL EXPIRE AT 730 AM PST FOR SAN MATEO...
SANTA CRUZ AND SANTA CLARA COUNTIES...

LAT...LON 3755 12226 3752 12217 3751 12216 3751 12213
      3750 12212 3749 12212 3748 12211 3748 12208
      3746 12205 3719 12210 3721 12231

$$

MM

The office that day

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

IssuedProductOfficeCountiesLasted
Feb 28, 4:28 AM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, Monterey, San Benito, City and County of San Francisco, San Mateo and 2 more4 hr
Feb 28, 8:23 AM PSTSpecial Marine WarningMTR37 min
Feb 28, 9:03 AM PSTAreal Flood AdvisoryMTRMonterey, San Benito, Santa Cruz87 min
Feb 28, 10:47 AM PSTSpecial Marine WarningMTR43 min

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.