Alert archive / California / Flash Flood Warnings in 2006

Flash Flood Warning 2, NWS San Diego, CA

February 17, 2006Orange County, California

NWS San Diego, CA issued this flash flood warning at Feb 17, 2006, 10:15 PM PST for Orange County, California. It was in force for 90 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Feb 17, 2006, 10:15 PM PST (06:15 UTC)
Expired: Feb 17, 2006, 11:45 PM PST
In force: 90 min
Issued by: NWS San Diego, CA
Area: Whole counties

County Orange County, CA

The radar

The Santa Ana Mts radar (KSOX), 20 km from the middle of the area, began a volume at 06:17 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

San Diego, CA (KNKX), launched 00:00Z, 6.3 hours before the alert went out and 111 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1262 m above ground
0-6 km bulk shear: 64 kt
0-1 km storm-relative helicity: -1 m²/s²
0-3 km storm-relative helicity: 107 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.

000 
WGUS56 KSGX 180619
FFWSGX
CAC059-180745-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN DIEGO CA
1015 PM PST FRI FEB 17 2006

THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTH CENTRAL ORANGE COUNTY IN SOUTHWEST CALIFORNIA
  THIS INCLUDES THE CITY OF YORBA LINDA

* UNTIL 1145 PM PST

* AT 1014 PM PST...FLASH FLOODING WAS REPORTED FROM THUNDERSTORMS
  ALONG A LINE EXTENDING FROM 18 MILES NORTHEAST OF YORBA LINDA TO 10
  MILES SOUTH OF SILVERADO CANYON...OR ALONG A LINE EXTENDING FROM
  RANCHO CUCAMONGA TO MISSION VIEJO...MOVING EAST AT 10 MPH.

* THUNDERSTORMS PRODUCING FLASH FLOODING WILL BE NEAR...
  RURAL EASTERN ORANGE COUNTY AT 1030 PM PST

IN ADDITION TO FLASH FLOODING...RAINFALL IS EXPECTED TO CAUSE DEBRIS 
FLOWS IN THE WATERSHEDS BURNED BY THE SIERRA AND YORBA LINDA FIRES. 
THE SOILS IN A BURN SCAR ARE HIGHLY ERODIBLE SO FLOOD WATERS CAN 
CONTAIN SIGNIFICANT AMOUNTS OF ASH...MUD... BOULDERS...AND 
VEGETATION.  WITHIN THE BURNED AREA AND DOWNSTREAM... THE POWERFUL 
FORCE OF RUSHING WATER...SOIL...AND ROCK CAN DESTROY 
CULVERTS...BRIDGES...ROADWAYS...AND STRUCTURES...AND CAN CAUSE 
INJURY OR DEATH IF CARE IS NOT TAKEN.

DRAINAGES IN FEATHERLY REGIONAL PARK...STREAM CROSSINGS ON STATE 
HIGHWAYS 91 AND 241 AND GYPSUM CANYON ROAD...AND SANTIAGO RESERVOIR 
COULD BE IMPACTED BY THESE EVENTS.  A SHORT PERIOD OF MODERATE 
RAINFALL ON THE BURNED WATERSHEDS CAN LEAD TO FLASH FLOODS AND 
DEBRIS FLOWS. RAINFALL THAT IS NORMALLY ABSORBED BY VEGETATION CAN 
RUN OFF ALMOST INSTANTLY. THIS CAUSES CREEKS AND DRAINAGE AREAS TO 
FLOOD MUCH SOONER DURING A STORM...AND WITH MORE WATER THAN IS 
NORMAL.

IN THE YORBA LINDA BURN AREA ACCORDING TO THRESHOLDS PROVIDED BY 
THE USGS. AREAS AFFECTED INCLUDE PARTS OF TELEGRAPH CANYON ROAD AND 
CARBON CANYON ROAD.

$$

IN ADDITION TO FLASH FLOODING...RAINFALL IS EXPECTED TO CAUSE DEBRIS 
FLOWS...MUD SLIDES...AND ROCK SLIDES WITH THIS STORM. MUD SLIDES AND 
ROCK SLIDES CAN POTENTIALLY TRAP AND KILL PEOPLE CAUGHT IN THEIR 
PATH.

RESIDENTS AND MOTORISTS IN AND BELOW RECENTLY BURNED AREAS SHOULD BE
ALERT TO HEAVY MUD AND DEBRIS FLOWS WHICH MAY BLOCK ROADS AND
CULVERTS. POTENTIALLY DANGEROUS FLOODING AND PROPERTY LOSS COULD
RESULT IN AREAS WHERE RUNOFF IS RESTRICTED OR BLOCKED.

LAT...LON 3394 11778 3378 11776 3374 11763 3380 11760
      3389 11769

$$

RB/MGM

3 follow-up statements

000 
WGUS76 KSGX 180655
FFSSGX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
1050 PM PST FRI FEB 17 2006

CAC059-180745-
ORANGE CA-
1050 PM PST FRI FEB 17 2006

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1145 PM PST FOR
NORTH CENTRAL ORANGE COUNTY...

AT 1039 PM PST...THE THUNDERSTORMS THAT WERE RESPONSIBLE FOR 
PRODUCING FLASH FLOODING WERE LOCATED ALONG A LINE EXTENDING FROM 8 
MILES EAST OF FREMONT CANYON TO 7 MILES SOUTHEAST OF FREMONT CANYON 
TO 7 MILES SOUTH OF FREMONT CANYON...OR ALONG A LINE EXTENDING FROM 
CORONA TO 8 MILES SOUTH OF CORONA TO 6 MILES NORTH OF MISSION 
VIEJO...MOVING EAST AT 10 MPH.

HEAVY RAIN HAS ENDED OVER THE SIERRA FIRE AND YORBA LINDA FIRE 
BURNED AREA...HOWEVER HEAVY RUNOFF...MUD SLIDES AND THE THREAT OF 
FLASH FLOODING WILL CONTINUE UNTIL 1145 PM...AND AFFECT AREAS 
DOWNSTREAM. 

ACCORDING TO THRESHOLDS PROVIDED BY THE U S GEOLOGICAL 
SERVICE...DEBRIS FLOWS ARE LIKELY IN THE FOLLOWING WATERSHEDS BURNED 
BY THE SIERRA FIRE... DRAINAGES IN FEATHERLY REGIONAL 
PARK...STREAM CROSSINGS ON STATE HIGHWAYS 91 AND 241 AND GYPSUM 
CANYON ROAD...AND SANTIAGO RESERVOIR. AND DEBRIS FLOWS ARE ALSO 
LIKELY IN THE YORBA LINDA BURN AREA AREAS...INCLUDING PARTS OF 
TELEGRAPH CANYON ROAD AND CARBON CANYON ROAD.

RAINFALL THAT IS NORMALLY ABSORBED BY VEGETATION CAN RUN OFF ALMOST 
INSTANTLY. THIS CAUSES CREEKS AND DRAINAGE AREAS TO FLOOD MUCH 
SOONER DURING A STORM...AND WITH MORE WATER THAN IS NORMAL. 

THE SOILS IN A BURN SCAR ARE HIGHLY ERODIBLE SO FLOOD WATERS CAN 
CONTAIN SIGNIFICANT AMOUNTS OF ASH...MUD... BOULDERS...AND 
VEGETATION.  WITHIN THE BURNED AREA AND DOWNSTREAM... THE POWERFUL 
FORCE OF RUSHING WATER...SOIL...AND ROCK CAN DESTROY 
CULVERTS...BRIDGES...ROADWAYS...AND STRUCTURES...AND CAN CAUSE 
INJURY OR DEATH IF CARE IS NOT TAKEN.

RESIDENTS AND MOTORISTS IN AND BELOW RECENTLY THE YORBA LINDA AND 
SIERRA FIRE BURNED AREAS SHOULD BE ALERT TO HEAVY MUD AND DEBRIS 
FLOWS WHICH MAY BLOCK ROADS AND CULVERTS. POTENTIALLY DANGEROUS 
FLOODING AND PROPERTY LOSS COULD RESULT IN AREAS WHERE RUNOFF IS 
RESTRICTED OR BLOCKED.

LAT...LON 3394 11778 3392 11780 3385 11773 3381 11781
      3379 11784 3381 11777 3377 11772 3378 11766
      3381 11761 3389 11769

$$

RB

000 
WGUS76 KSGX 180731
FFSSGX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
1131 PM PST FRI FEB 17 2006

CAC059-180745-
ORANGE CA-
1131 PM PST FRI FEB 17 2006

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1145 PM PST FOR
NORTH CENTRAL ORANGE COUNTY...

AT 1117 PM PST...NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWED 
ANOTHER LINE OF MODERATE RAINSHOWERS MOVING TOWARDS NORTHERN ORANGE 
COUNTY. THESE SHOWERS WERE LOCATED ALONG A LINE EXTENDING FROM 24 
MILES NORTH OF FREMONT CANYON TO 17 MILES NORTHWEST OF FREMONT 
CANYON TO 18 MILES WEST OF FREMONT CANYON...OR ALONG A LINE 
EXTENDING FROM SAN DIMAS TO ROWLAND HEIGHTS TO CYPRESS...MOVING EAST 
AT 20 MPH.

THUNDERSTORMS PRODUCING FLASH FLOODING WILL BE NEAR...
  9 MILES NORTHWEST OF FREMONT CANYON BY 1145 PM PST

HEAVY RUNOFF...MUD SLIDES AND THE THREAT OF FLASH FLOODING FROM RAIN 
THAT FELL EARLIER WILL CONTINUE UNTIL 1145 PM...AND AFFECT THE  
SIERRA FIRE AND YORBA LINDA FIRE BURNED AREAS AND AREAS DOWNSTREAM. 

ACCORDING TO THRESHOLDS PROVIDED BY THE U S GEOLOGICAL 
SERVICE...DEBRIS FLOWS ARE LIKELY IN THE FOLLOWING WATERSHEDS BURNED 
BY THE SIERRA FIRE... 

DRAINAGES IN FEATHERLY REGIONAL PARK...STREAM CROSSINGS ON STATE 
HIGHWAYS 91 AND 241 AND GYPSUM CANYON ROAD...AND SANTIAGO 
RESERVOIR..

AND DEBRIS FLOWS ARE ALSO LIKELY IN THE YORBA LINDA BURN AREA 
AREAS...INCLUDING PARTS OF TELEGRAPH CANYON ROAD AND CARBON CANYON 
ROAD.

RAINFALL THAT IS NORMALLY ABSORBED BY VEGETATION CAN RUN OFF ALMOST 
INSTANTLY. THIS CAUSES CREEKS AND DRAINAGE AREAS TO FLOOD MUCH 
SOONER DURING A STORM...AND WITH MORE WATER THAN IS NORMAL. 

THE SOILS IN A BURN SCAR ARE HIGHLY ERODIBLE SO FLOOD WATERS CAN 
CONTAIN SIGNIFICANT AMOUNTS OF ASH...MUD... BOULDERS...AND 
VEGETATION.  WITHIN THE BURNED AREA AND DOWNSTREAM... THE POWERFUL 
FORCE OF RUSHING WATER...SOIL...AND ROCK CAN DESTROY 
CULVERTS...BRIDGES...ROADWAYS...AND STRUCTURES...AND CAN CAUSE 
INJURY OR DEATH IF CARE IS NOT TAKEN.

RESIDENTS AND MOTORISTS IN AND BELOW RECENTLY BURNED AREAS SHOULD BE
ALERT TO HEAVY MUD AND DEBRIS FLOWS WHICH MAY BLOCK ROADS AND
CULVERTS. POTENTIALLY DANGEROUS FLOODING AND PROPERTY LOSS COULD
RESULT IN AREAS WHERE RUNOFF IS RESTRICTED OR BLOCKED.

LAT...LON 3394 11778 3392 11780 3385 11773 3381 11781
      3379 11784 3381 11777 3377 11772 3378 11766
      3381 11761 3389 11769

$$


RB

000 
WGUS76 KSGX 180745
FFSSGX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
1142 PM PST FRI FEB 17 2006

CAC059-180752-
ORANGE CA-
1142 PM PST FRI FEB 17 2006

...THE FLASH FLOOD WARNING FOR NORTH CENTRAL ORANGE COUNTY EXPIRES AT
1145 PM PST...

FLASH FLOODING FROM EARLIER RAINS...AROUND 10 PM OVER THE SIERRA 
FIRE AND YORBA LINDA FIRE BURNED AREAS AND AREAS DOWNSTREAM HAS 
LIKELY ENDED.  

A NEW LINE OF SHOWERS THAT WILL MOVE ACROSS THE YORBA LINDA AND  
SIERRA FIRE BURNED AREAS BETWEEN NOW AND 1215 AM PST IS NOT EXPECTED 
TO PRODUCE HEAVY RAIN OR ADDITIONAL FLASH FLOODING. 

LAT...LON 3394 11778 3392 11780 3385 11773 3381 11781
      3379 11784 3381 11777 3377 11772 3378 11766
      3381 11761 3389 11769

$$

RB

The office that day

Everything else NWS San Diego, CA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 18, 3:28 AM PST	Winter Weather Advisory	SGX	Riverside, San Bernardino, San Diego	34 hr
Feb 18, 6:56 AM PST	Marine Weather Statement	SGX		11 hr

Nearby

Flash Flood Warnings in California, 2006 Every flash flood warning in 2006

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.