Alert archive / California / Severe Thunderstorm Warnings in 2012
Severe Thunderstorm Warning 22, NWS San Diego, CA
NWS San Diego, CA issued this severe thunderstorm warning at Aug 21, 2012, 2:47 PM PDT for San Diego County, California. It was in force for 28 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
- Aug 21, 2012, 2:47 PM PDT (21:47 UTC)
- Expired
- Aug 21, 2012, 3:15 PM PDT
- In force
- 28 min
- Issued by
- NWS San Diego, CA
- Area
- Storm-based polygon
County San Diego County, CA
The radar
The San Diego radar (KNKX), 65 km from the middle of the area, began a volume at 21:48 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.
Did it verify
Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.
Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.
The nearest sounding before it
San Diego, CA (KNKX), launched 12:00Z, 9.8 hours before the alert went out and 81 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 899 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- -7 m²/s²
- 0-3 km storm-relative helicity
- 20 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
445 WUUS56 KSGX 212147 SVRSGX CAC073-212215- /O.NEW.KSGX.SV.W.0022.120821T2147Z-120821T2215Z/ BULLETIN - EAS ACTIVATION REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE SAN DIEGO CA 247 PM PDT TUE AUG 21 2012 THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... EAST CENTRAL SAN DIEGO COUNTY IN SOUTHWEST CALIFORNIA... * UNTIL 315 PM PDT * AT 242 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR MOUNT LAGUNA...OR 22 MILES WEST OF OCOTILLO...AND MOVING NORTH AT 10 MPH. * OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO CANEBRAKE...AGUA CALIENTE SPRINGS AND JUST EAST OF PINE VALLEY. PRECAUTIONARY/PREPAREDNESS ACTIONS... IN ADDITION TO DAMAGING WINDS...CONTINUOUS CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS IMMEDIATELY! LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS. REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. && LAT...LON 3302 11643 3301 11613 3273 11624 3279 11650 TIME...MOT...LOC 2145Z 190DEG 8KT 3285 11635 $$ JJT
1 follow-up statement
904 WWUS56 KSGX 212206 SVSSGX SEVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE SAN DIEGO CA 306 PM PDT TUE AUG 21 2012 CAC073-212215- /O.CON.KSGX.SV.W.0022.000000T0000Z-120821T2215Z/ SAN DIEGO CA- 306 PM PDT TUE AUG 21 2012 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM PDT FOR EAST CENTRAL SAN DIEGO COUNTY... AT 301 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS ALSO PRODUCING HEAVY RAINFALL. THIS STORM WAS LOCATED NEAR MOUNT LAGUNA...OR 22 MILES NORTHWEST OF OCOTILLO...MOVING NORTH AT 5 MPH. OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO CANEBRAKE...AGUA CALIENTE SPRINGS AND AREAS JUST EAST OF PINE VALLEY. PRECAUTIONARY/PREPAREDNESS ACTIONS... IN ADDITION TO SMALL HAIL AND DAMAGING WINDS...CONTINUOUS CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS IMMEDIATELY! LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS. REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. && LAT...LON 3302 11643 3301 11613 3273 11624 3279 11650 TIME...MOT...LOC 2204Z 190DEG 8KT 3289 11634 $$ JJT
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 21, 2:05 PM PDT, 42 minutes earlier.
Area forecast discussion, Aug 21, 2:05 PM PDT, 42 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
205 PM AM PDT TUE AUG 21 2012
.SYNOPSIS...
THE COMBINATION OF MONSOON MOISTURE AND A TROUGH MOVING TOWARDS
CENTRAL CALIFORNIA HAVE MADE CONDITIONS FAVORABLE FOR THUNDERSTORMS
WITH HEAVY DOWNPOURS THROUGH THIS EVENING. SOME OF THESE COULD LEAD
TO FLASH FLOODING...MAINLY OVER THE MOUNTAINS AND DESERT AREAS.
THERE IS ALSO A SLIGHT CHANCE OF THUNDERSTORMS CONTINUING THROUGH
TONIGHT...SOME OF THESE MAY AFFECT THE COAST AND INLAND VALLEY
AREAS. THUNDERSTORMS ARE AGAIN POSSIBLE ON WEDNESDAY. A TROUGH
MOVING INLAND WILL BRING DRIER SOUTHWEST FLOW ALOFT THURSDAY. THIS
WILL END THE THUNDERSTORM THREAT BUT ALSO DEEPEN THE MARINE LAYER.
HIGH PRESSURE WILL REBUILD OVER THE AREA FRIDAY AND SATURDAY.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.REMAINDER OF TODAY THROUGH THURSDAY...
STRATUS CLOUDS PENETRATED MUCH FURTHER INLAND THIS MORNING THAN LAST
SEVERAL DAYS AND STILL HAVE NOT CLEARED THE SOUTHERN ORANGE COUNTY
AND NORTHERN SAN DIEGO COUNTY COASTS. THIS WAS A RESULT OF A COASTAL
EDDY GENERATED BY THE MODERATE TO STRONG NORTHWEST WINDS OVER THE
OFFSHORE WATERS. AT THE SAME TIME THE AIR MASS OVER LAND HAS BECOME
INCREASINGLY MOIST AND CONDITIONALLY UNSTABLE AS MONSOON MOISTURE
STREAMS NORTHWARD FROM MEXICO. PRECIPITABLE WATER VALUES ARE NEAR OR
ABOVE 2 INCHES AND EXPECTED TO REMAIN SO THROUGH TONIGHT. DAYTIME
HEATING AND CONVERGING WINDS OVER THE MOUNTAINS HAVE RESULTED IN
MORE AND EARLIER THUNDERSTORM FORMATION TODAY COMPARED TO THE PAST
TWO DAYS. THE THREAT OF THUNDERSTORMS IS NOT EXPECTED TO END WITH
SUNSET...AS AN UPPER TROUGH LOCATED OFF THE CENTRAL CALIFORNIA COAST
AND MOVING SLOWLY EASTWARD INTERACTS WITH THE UNSTABLE AIR MASS
TONIGHT THROUGH WEDNESDAY MORNING...CREATING A THREAT OF
ELEVATED/NOCTURNAL CONVECTION TO ALL AREAS. DAYTIME HEATING ON
WEDNESDAY AND EVEN INTO THURSDAY SHOULD AGAIN FOCUS THUNDERSTORM
DEVELOPMENT OVER THE MOUNTAINS.
.THURSDAY EVENING THROUGH TUESDAY AUGUST 28...CONSENSUS OF MODELS
SHOW HIGH PRESSURE RIDGE REBUILDING ACROSS THE AREA THROUGH SATURDAY
THEN SHIFTING EAST SUNDAY AND MONDAY...THEN RIDGE FLATTENING ON
TUESDAY AS ZONAL FLOW/STORM TRACK DEVELOPS ALONG 40N LATITUDE. FOR
SW CALIFORNIA THIS SHOULD YIELD A WARMING AND DRYING TREND THROUGH
SATURDAY WITH A LOWERING MARINE LAYER...THEN A SLIGHT COOLING TREND
WITH DEEPER MARINE LAYER AND GUSTY SOUTHWEST WINDS THROUGH TUESDAY.
&&
.AVIATION...
212000Z...COAST/VALLEYS...VFR CONDS FORECAST THROUGH 04Z THIS
EVENING. STRATUS...WITH BASES AROUND 1100 FT MSL AND TOPS NEAR 2000
FT MSL...WILL QUICKLY DEVELOP CIGS ALONG THE COAST TONIGHT BTWN
03-06Z...AND PUSH AROUND 20 SM INLAND BY MID WED MORNING. CIGS MAY
DEVELOP OVER KCRQ AS EARLY AS 01Z. STRATUS WILL CLEAR TOWARD THE
COAST BTWN 17-18Z WED MORNING...AND HUG THE COAST THROUGHOUT THE DAY
WED.
MTNS/DESERTS...SCT-BKN CLOUDS LAYERED FROM 10K FT MSL TO 40K FT MSL
WITH ISOLATED/SCATTERED SHOWERS AND TSTMS POSSIBLE THROUGH THE
REMAINDER OF THE TAF PERIOD. TSTMS MAY PRODUCE STRONG
UP/DOWNDRAFTS...GUSTY SURFACE WINDS AND LOWERED VIS. AWAY FROM
SHOWERS/TSTMS...VFR CONDS FORECAST THROUGH THE TAF PERIOD.
&&
.FIRE WEATHER...
IN REGARDS TO DRY LIGHTNING THREAT...THERE IS A SIGNIFICANT
MOISTURE/PRECIPITABLE WATER GRADIENT ACROSS SOUTHERN CALIFORNIA
THAT REMAINS MORE OR LESS STATIONARY ALONG A NEWPORT BEACH TO
VICTORVILLE TO BARSTOW LINE THROUGH WEDNESDAY. WEST OF THIS LINE THE
AIR REMAINS RELATIVELY DRY BELOW 10000 FT MSL WITH PRECIPITABLE
WATER VALUES CLOSER TO ONE INCH...WHILE EAST OF THE LINE VALUES ARE
CLOSE TO TWO INCHES. FOR THOSE AREAS EAST OF THE LINE HEAVY WETTING
TRAINS ARE LIKELY TO ACCOMPANY MOST THUNDERSTORMS. WEST OF THE LINE
DRY LIGHTNING IS MORE LIKELY...AREAS OF CONCERN WOULD BE THE CHINO
HILLS ABOVE THE MARINE AIR INFLUENCE...THE FRONT COUNTRY WEST OF
INTERSTATE 15...THE SAN GABRIEL MOUNTAINS...AND THE HIGH DESERT
VALLEYS WEST OF INTERSTATE 15. FOR THE ORANGE COUNTY COASTAL PLAIN
AND INLAND EMPIRE BELOW 1500 FEET...THE MARINE AIR INFLUENCE WITH
MODERATE OR BETTER HUMIDITY RECOVERY OVERNIGHT SHOULD SLOW FIRE
GROWTH FROM ANY LIGHTNING STRIKES OR OTHER IGNITION SOURCES.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH UNTIL 8 PM PDT THIS EVENING FOR THE APPLE AND
LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE COUNTY
MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO
COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.
PZ...NONE.
&&
PUBLIC/FIRE WEATHER...BALFOUR
SHORT TERM WARNINGS...HARRISON
AVIATION/MARINE...JJTHazardous weather outlook, Aug 21, 10:25 AM PDT, 4 hours 22 minutes before
HAZARDOUS WEATHER OUTLOOK...CORRECTION NATIONAL WEATHER SERVICE SAN DIEGO CA 1025 AM PDT TUE AUG 21 2012 CAZ055-056-058-060>062-220100- SAN BERNARDINO COUNTY MOUNTAINS-RIVERSIDE COUNTY MOUNTAINS- SAN DIEGO COUNTY MOUNTAINS-APPLE AND LUCERNE VALLEYS- COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS- 1025 AM PDT TUE AUG 21 2012 ...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EXTREME SOUTHWESTERN CALIFORNIA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WITH HEAVY DOWNPOURS ARE POSSIBLE TODAY. THERE IS A SLIGHT CHANCE THAT THUNDERSTORMS MAY CONTINUE OVERNIGHT...MAINLY ACROSS THE SAN BERNARDINO COUNTY MOUNTAINS AND DESERTS. THE FLASH FLOOD POTENTIAL IS MODERATE TO HIGH. FLASH FLOODING IS POSSIBLE THROUGH THIS EVENING. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THUNDERSTORMS ARE POSSIBLE THROUGH LATE WEDNESDAY AFTERNOON. FOR THURSDAY THROUGH MONDAY...NO SIGNIFICANT WEATHER IS EXPECTED. .SPOTTER INFORMATION STATEMENT... SKYWARN WEATHER ACTIVATION IS REQUESTED FOR SAN BERNARDINO COUNTY...RIVERSIDE COUNTY...AND SAN DIEGO COUNTY ACROSS THE MOUNTAINS AND DESERT AREAS. CAZ042-043-048-050-057-220100- ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS- SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE- SAN DIEGO COUNTY VALLEYS-SANTA ANA MOUNTAINS AND FOOTHILLS- 748 AM PDT TUE AUG 21 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EXTREME SOUTHWESTERN CALIFORNIA. .DAY ONE...TODAY AND TONIGHT... THERE IS A SLIGHT CHANCE OF THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. THE FLASH FLOOD POTENTIAL IS LOW. HOWEVER BRIEF HEAVY DOWNPOURS ARE POSSIBLE AND MAY LEAD TO MINOR FLOODING OF LOW LYING URBAN AREAS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THERE IS A SLIGHT CHANCE OF THUNDERSTORMS WEDNESDAY. FOR THURSDAY THROUGH MONDAY...NO HAZARDOUS WEATHER IS EXPECTED. .SPOTTER INFORMATION STATEMENT... SKYWARN WEATHER ACTIVATION IS NOT REQUESTED AT THIS TIME...HOWEVER SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER. BALFOUR
In the hours before
Local storm report, Aug 21, 2:45 PM PDT, 2 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
245 PM PDT TUE AUG 21 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0215 PM FLASH FLOOD 4 SE RANCHITA 33.16N 116.47W
08/21/2012 SAN DIEGO CA DEPT OF HIGHWAYS
AT 215 PM PDT BORREGO COUNTY ROAD MAINTENENCE CREW
REPORTED WATER AND DEBREE FLOWING ACROSS SAN FELIPE ROAD
JUST NORTH OF HIGHWAY 78 BETWEEN MILE MARKER 12 AND 14.
&&
JTHOMASThe office that day
Everything else NWS San Diego, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 7:39 AM PDT | Flood Watch | SGX | Riverside, San Bernardino, San Diego | 88 min |
| Aug 21, 9:07 AM PDT | Flash Flood Watch | SGX | Riverside, San Bernardino, San Diego | 11 hr |
| Aug 21, 1:50 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 40 min |
| Aug 21, 2:08 PM PDT | Flash Flood Warning | SGX | San Diego | 112 min |
| Aug 21, 3:10 PM PDT | Areal Flood Advisory | SGX | Riverside, San Diego | 2 hr |
| Aug 21, 3:12 PM PDT | Areal Flood Advisory | SGX | San Diego | 2 hr |
| Aug 21, 3:15 PM PDT | Severe Thunderstorm Warning | SGX | San Diego | 35 min |
Nearby
Severe Thunderstorm Warnings in California, 2012Every severe thunderstorm 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.