Flash Flood Warning 40, NWS San Diego, CA

000 
WGUS76 KSGX 042117
FFSSGX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
217 PM PDT MON AUG 4 2008

CAC065-042230-
/O.CON.KSGX.FF.W.0040.000000T0000Z-080804T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
RIVERSIDE CA-
217 PM PDT MON AUG 4 2008

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 330 PM PDT FOR
CENTRAL RIVERSIDE COUNTY...

AT 207 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A THUNDERSTORM PRODUCING FLASH FLOODING OVER THE WARNED
AREA.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO RANCHO 
MIRAGE...PALM SPRINGS...PALM DESERT COUNTRY...PALM 
DESERT...CATHEDRAL CITY AND HIGHWAY 74 BETWEEN MOUNTAIN CENTER AND 
PALM DESERT. 

STEEP TERRAIN AND THE WATERSHEDS BURNED THIS FALL ARE PARTICULARLY 
SUSCEPTIBLE TO FLASH FLOODS AND DEBRIS FLOWS DURING RAINSTORMS. A 
SHORT PERIOD OF EVEN MODERATE RAINFALL ON STEEP TERRAIN OR A BURNED 
WATERSHED CAN LEAD TO DEBRIS FLOWS. RAINFALL THAT IS NORMALLY 
ABSORBED INTO HILLSLOPE SOILS CAN RUN OFF ALMOST INSTANTLY AFTER 
VEGETATION HAS BEEN REMOVED BY WILDFIRE. THIS CAUSES MUCH GREATER 
AND MORE RAPID RUNOFF THAN IS NORMAL FROM CREEKS AND DRAINAGE AREAS. 
THE HIGHLY ERODIBLE SOILS IN A BURN SCAR ALLOW FLOOD WATERS TO 
ENTRAIN LARGE AMOUNTS OF ASH, MUD...BOULDERS...AND UNBURNED 
VEGETATION. WITHIN THE BURNED AREA AND DOWNSTREAM...THE FORCE OF 
RUSHING WATER...SOIL AND ROCK CAN DESTROY 
CULVERTS...BRIDGES...ROADWAYS AND BUILDINGS...POTENTIALLY CAUSING 
INJURY OR DEATH.

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 3380 11666 3385 11650 3384 11630 3353 11628
      3351 11654

$$

ATKIN

000 
WGUS76 KSGX 042227
FFSSGX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
327 PM PDT MON AUG 4 2008

CAC065-042237-
/O.EXP.KSGX.FF.W.0040.000000T0000Z-080804T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
RIVERSIDE CA-
327 PM PDT MON AUG 4 2008

...THE FLASH FLOOD WARNING WILL EXPIRE AT 330 PM PDT FOR CENTRAL
RIVERSIDE COUNTY...

LAT...LON 3380 11666 3385 11650 3384 11630 3353 11628
      3351 11654

$$

ATKIN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
900 AM PDT MON AUG 4 2008

.SYNOPSIS...
MONSOONAL MOISTURE WILL BRING SOME AFTERNOON AND EVENING
THUNDERSTORMS TO THE MOUNTAINS AND DESERTS TODAY. A SMALLER CHANCE
WILL CONTINUE DURING THE AFTERNOONS TUESDAY AND WEDNESDAY. A
DISRUPTED MARINE LAYER WILL BRING PATCHY NIGHT AND MORNING LOW
CLOUDS AND FOG ALONG THE COAST. A WEAK TROUGH OF LOW PRESSURE OFF
THE WEST COAST WILL BRING DRIER WEATHER LATER THIS WEEK.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

THE MASS OF CLOUDS THAT MOVED THROUGH THE REGION THIS MORNING
BROUGHT NOTHING IN THE WAY OF RAIN...BUT THE BIG STORY IS THAT THE
AIR MASS HAS CHANGED. THE MARINE INFLUENCE IS OUT AND THE MONSOON
INFLUENCE IS IN FOR A COUPLE DAYS. THAT WILL LEAD TO SCATTERED
THUNDERSTORMS IN THE MTNS AND DESERTS THIS AFTERNOON. EASTERLY FLOW
MAY GUIDE A FEW OF THOSE TSTORMS INTO THE INLAND VALLEYS. THE
MOISTURE IS HIGH ENOUGH AND THE STORMS WILL BE STATIONARY ENOUGH TO
ELEVATE THE FLASH FLOOD THREAT...ENOUGH FOR A FLASH FLOOD WATCH FOR
THIS AFTERNOON AND EVE. IT WILL BE MUCH WARMER TODAY ESPECIALLY AT
THE COAST AND NOTICEABLY MUGGIER EVERYWHERE. THE MID LEVEL MONSOON
MOISTURE DECREASES DURING THE DAY TUE BUT HANGS ON WED AND EVEN THU.
THE MARINE LAYER CLOUD DECK SHOULD BE REBOUNDING A LITTLE BY
THEN...BUT WILL REMAIN SHALLOW...SO THE NOCTURNAL LOW CLOUDS WILL
NOT BE EXTENSIVE. THE UPPER TROUGH OVER THE PACIFIC NORTHWEST IS
FORECAST TO EXTEND SOUTHWARD JUST A TOUCH ON FRI...ENOUGH TO PRODUCE
DRIER SOUTHWEST FLOW OVER SOCAL. THEN IT RECEDES EVER SO SLIGHTLY
OVER THE WEEKEND TO ALLOW A LITTLE MONSOON MOISTURE TO SLIP BACK
INTO THE REGION.

&&

.AVIATION...
041500Z...MONSOON AIR MASS FROM THE EAST APPEARS TO BE KEEPING THE
MARINE LAYER WELL TO THE WEST OF THE COAST. SOME PATCHES OF SCT
STRATUS AT 1000 FT HAVE FORMED BUT WILL BURN OFF BY 17Z. EXPECT
SIMILAR LACK OF STRATUS PATTERN TONIGHT. ABOVE THE MARINE
LAYER...INCLUDING THE MOUNTAINS AND DESERTS...MID AND HIGH LEVEL
MOISTURE OVER THE AREA WILL RESULT IN SCATTERED THUNDERSTORMS IN THE
MOUNTAINS AND ADJACENT DESERTS. BEST CHANCE WILL BE THIS AFTERNOON.
EXPECT BASES TO BE AT OR ABOVE FL080...WITH ISOLATED TOPS TO FL500
AT TIMES. OTHERWISE CIGS AND VIS WILL REMAIN UNRESTRICTED THROUGH
THE DAY. PG

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH FROM NOON PDT TODAY THROUGH THIS EVENING FOR
     APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-RIVERSIDE COUNTY
     MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY
     DESERTS-SAN DIEGO COUNTY MOUNTAINS.

PZ...NONE.

&&

PUBLIC...MM
AVIATION/MARINE...PG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN DIEGO CA
400 AM PDT MON AUG 4 2008

CAZ042-043-048-050-055>058-060>062-042300-
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-SAN
BERNARDINO COUNTY MOUNTAINS-RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO
COUNTY MOUNTAINS-APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-SAN
DIEGO COUNTY DESERTS-
400 AM PDT MON AUG 4 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ALL OF OF EXTREME SOUTHWESTERN
CALIFORNIA.

.DAY ONE...TODAY AND TONIGHT

FOR THE MOUNTAINS AND DESERTS...FLASH FLOOD WATCH...SEE LAXFFASGX.
THE FLASH FLOOD POTENTIAL INDEX IS MODERATE... THUNDERSTORMS ARE
EXPECTED TO DEVELOP AND ISOLATED FLASH FLOODING IS POSSIBLE.

FOR THE FAR INLAND VALLEYS...THE FLASH FLOOD POTENTIAL INDEX IS LOW.
THE RISK OF FLASH FLOODING IS MINIMAL.

ELSEWHERE...NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

FOR TUESDAY FOR THE MOUNTAINS AND DESERTS...THE FLASH FLOOD
POTENTIAL INDEX IS MODERATE... THUNDERSTORMS ARE EXPECTED
TO DEVELOP AND ISOLATED FLASH FLOODING IS POSSIBLE.

OTHERWISE...NO HAZARDOUS WEATHER IS EXPECTED.

.SPOTTER INFORMATION STATEMENT...
SKYWARN ACTIVATION MAY BE NEEDED FOR THE MOUNTAINS AND DESERTS FOR
THIS AFTERNOON AND EVENING. WEATHER SPOTTERS ARE ENCOURAGED
TO REPORT SIGNIFICANT WEATHER CONDITIONS.

MARTIN