Alert archive / California / Flash Flood Warnings in 2011

Flash Flood Warning 6, NWS San Francisco Bay Area, CA

September 10, 2011San Benito County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Sep 10, 2011, 4:41 PM PDT for San Benito County, California. It was in force for 34 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
Sep 10, 2011, 4:41 PM PDT (23:41 UTC)
Expired
Sep 10, 2011, 5:15 PM PDT
In force
34 min
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

County San Benito County, CA

The radar

The San Francisco radar (KMUX), 108 km from the middle of the area, began a volume at 23:44 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, 11.7 hours before the alert went out and 175 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 2011-09-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 91 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 12:00Z on 2011-09-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 41 square meters per square second.193958Sfc1 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
91 J/kg
Mixed-layer CIN
-887 J/kg
Mixed-layer LCL
2154 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
41 m²/s²
0-3 km storm-relative helicity
33 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.

313 
WGUS56 KMTR 102341
FFWMTR
CAC069-110015-
/O.NEW.KMTR.FF.W.0006.110910T2341Z-110911T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
441 PM PDT SAT SEP 10 2011

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

* FLASH FLOOD WARNING FOR...
  SAN BENITO COUNTY IN WESTERN CALIFORNIA...

* UNTIL 515 PM PDT.

* AT 432 PM PDT...NWS DOPPLER RADAR AND AUTOMATED RAIN GAGES
  INDICATED... FROM A THUNDERSTORM 9 MILES EAST OF PINNACLES RAWS...
  OR 27 MILES NORTHEAST OF ARROYO SECO...MOVING WEST AT 5 MPH.

* THE STORM PRODUCING HEAVY RAIN WILL MOVE ACROSS HIGHWAY 25 SOUTH 
OF PINNACLES NATIONAL MONUMENT AND WILL RESULT IN LOCALIZED PONDING ON THE 
ROADWAYS AND FLOODING OF PREVIOUSLY DRY GULCHES. OTHERWISE THE STORM 
WILL REMAIN OVER MAINLY RURAL AREAS OF THE SAN BENITO COUNTY.

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 3648 12120 3652 12092 3639 12090 3636 12109

$$

LARRY
2 follow-up statements
280 
WGUS76 KMTR 110004
FFSMTR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
504 PM PDT SAT SEP 10 2011

CAC069-110015-
/O.CON.KMTR.FF.W.0006.000000T0000Z-110911T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SAN BENITO CA-
504 PM PDT SAT SEP 10 2011

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 515 PM PDT FOR SAN
BENITO COUNTY...

AT 457 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A THUNDERSTORM PRODUCING FLASH FLOODING.  THIS STORM WAS
LOCATED 6 MILES SOUTHEAST OF PINNACLES RAWS...OR 24 MILES NORTHEAST
OF ARROYO SECO...MOVING SOUTHWEST AT 5 MPH.

THIS THUNDERSTORM WITH EXCESSIVE RAIN IS SLOWLY MOVING ACROSS HIGH 
WAY 25 BUT WILL OTHERWISE REMAIN OVER MAINLY RURAL AREAS OF THE 
INDICATED COUNTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...COUNTRY ROADS...AS WELL AS FARMLAND ALONG THE
BANKS OF CREEKS AND STREAMS.

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.

FLOODING IS OCCURRING OR IS IMMINENT. IT IS IMPORTANT TO KNOW WHERE
YOU ARE RELATIVE TO STREAMS...RIVERS...OR CREEKS WHICH CAN BECOME
KILLERS IN HEAVY RAINS. CAMPERS AND HIKERS SHOULD AVOID STREAMS OR
CREEKS.

&&

LAT...LON 3648 12120 3652 12092 3639 12090 3636 12109

$$

LARRY
081 
WGUS76 KMTR 110019
FFSMTR

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
519 PM PDT SAT SEP 10 2011

CAC069-110029-
/O.EXP.KMTR.FF.W.0006.000000T0000Z-110911T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SAN BENITO CA-
519 PM PDT SAT SEP 10 2011

...THE FLASH FLOOD WARNING HAS EXPIRED FOR SAN BENITO COUNTY...

LAT...LON 3648 12120 3652 12092 3639 12090 3636 12109

$$

LARRY

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 10, 7:43 AM PDTSmall Craft AdvisoryMTR15 hr
Sep 10, 4:22 PM PDTSpecial Weather StatementMTRSan Benito23 min

Nearby

Flash Flood Warnings in California, 2011Every flash flood warning in 2011

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.