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Sunday's forecast


Outer Bamnks diving on the Great Escape Southern California Live-Aboard Dive Boat


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Posted by Diver Z on January 26, 2008 at 17:40:41:

Thunder and waterspouts? Are any boats still planning on running Sunday?


SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
340 PM PST SAT JAN 26 2008

.SHORT TERM...TONIGHT-MONDAY. IMPRESSIVE STORM SYSTEM POISED TO MAKE LANDFALL LATER TONIGHT WITH ALL KINDS OF FIREWORKS ANTICIPATED ON SUNDAY. AFTERNOON SATELLITE IMAGERY CONFIRMS RAPID ENHANCEMENT ALONG THE DEEP SUBTROPICAL MOISTURE PLUME SPREADING INTO SOUTHWEST CALIFORNIA. CLOUDS ARE ALSO COOLING AND PHASING WITH THE MAIN FRONTAL BAND FURTHER WEST ALONG 123W. ALL MODEL DATA REMAINS CONSISTENT WITH TIMING AND INTENSITY OF THIS EVENT. WE EXPECT STEADY PRECIPITATION TO INCREASE OVER THE ENTIRE 4-COUNTY AREA EARLY THIS EVENING AND BECOME HEAVY AT TIMES OVERNIGHT AS HIGHER PRECIPITABLE WATER VALUES ARE ENTRAINED INTO THE FRONT. RAINFALL AMOUNTS WILL RANGE FROM 0.75 - 1.5 INCHES BY SUNRISE ON SUNDAY WITH HEAVIER AMOUNTS ON THE SOUTH FACING MOUNTAINS.

RAINFALL WILL CONTINUE TO BE HEAVY DUE TO SOUTHERLY WINDS AND OROGRAPHIC FLOW FOR THE MOUNTAINS WITH JUST A SLIGHT DECREASE IN ACTIVITY EARLY SUNDAY MORNING. THEN...THE UPPER LOW AND COLD AIR ALOFT APPROACHES THE AREA BY MIDDAY. LOCATION OF THE UPPER LOW WILL BE WEST OF POINT CONCEPTION WITH A VERY STRONG 150KT JET STREAM ALONG THE MEXICAN BORDER. THIS IS A CLASSIC SEVERE THUNDERSTORM PATTERN FOR SMALL SUPERCELLS WITH ROTATION AS THEY MOVE THROUGH THE BIGHT AND INTO COASTAL AREAS OF VENTURA AND LOS ANGELES COUNTIES. INSTABILITY PARAMETERS INCLUDE 660 J\/KG SURFACE-BASED CAPE...-3 C LIFTED INDEX VALUES AND MODERATE LAPSE RATES OF 7.5 C/KM UP TO 500MB TOMORROW AFTERNOON. THUNDERSTORMS SHOULD MOVE ALONG AT A RAPID CLIP OF 30-35 MPH ADDING MOMENTUM TO ANY SIGNIFICANT DOWNBURST FROM A CELL. NUMEROUS WATERSPOUTS ARE POSSIBLE FOR COASTAL WATERS IN THIS TYPE OF ENVIRONMENT. THE THREAT OF THUNDERSTORMS WILL PERSIST INTO THE SUNDAY NIGHT PERIOD.

RAIN TOTALS ARE STILL ON-TRACK FOR 2-4 INCHES FOR VALLEYS/COASTS AND 4-8 INCHES FOR THE MOUNTAINS...HOWEVER TOTALS COULD BE QUITE VARIABLE DUE TO THE CONVECTIVE NATURE OF THE STORM. SNOW LEVELS WILL RISE OVERNIGHT TO 7K FEET...THEN LOWER TO 5K SUNDAY AFTERNOON AND 4K BY MONDAY MORNING. SNOWFALL TOTALS OF 1-2 FEET WILL BE LIKELY IN THE MOUNTAINS ABOVE 7000 FEET...WITH HIGHER AMOUNTS POSSIBLE. RECENT RAIN EVENTS IN THE PAST WEEK AND DEEP SNOWPACK IN THE MOUNTAINS HAS PRIMED LOWER ELEVATIONS TO BE FLASHY WHEN THE HEAVY RAIN ARRIVES DUE TO SATURATED SOILS AND ADDED WATER IN THE RIVER SYSTEM. BURN AREAS WILL BE EXTREMELY VULNERABLE TO FLASH FLOODS AND DEBRIS FLOWS DURING THE ACTIVE PERIOD OF EXPECTED THUNDERSTORMS SUNDAY AFTERNOON AND NIGHT. SHORT DURATION INTENSE RAINFALL OF 15-60 MINUTES WILL BE EXTREMELY DANGEROUS FOR THE BURN AREAS DURING THIS PERIOD. WE COULD SEE SOME MAINSTEM RIVER FLOODING WITH THE VENTURA AND SANTA CLARA RIVERS APPROACHING BANKFULL AND POSSIBLE CREST ABOVE FLOOD STAGE NEAR THE MAIN STREET BRIDGE IN VENTURA ON THE VENTURA RIVER LATE SUNDAY MORNING.

WINDS ARE EXPECTED TO INCREASE OVERNIGHT WITH STRONG SOUTH TO SOUTHEAST WINDS AHEAD OF THE FRONTAL SYSTEM. GUSTS TO 50 MPH IN THE VALLEYS AND 70 MPH IN THE MOUNTAINS ARE ANTICIPATED THROUGH SUNDAY MORNING...WITH A DECREASE IN THE AFTERNOON AS WINDS VEER TO SOUTHWEST AND WEST. GUSTY WINDS COULD OCCUR IN AND NEAR THUNDERSTORMS SUNDAY AFTERNOON/NIGHT.

.LONG TERM...MONDAY NIGHT-SATURDAY. NOT A LOT OF TIME TO LOOK AT THE EXTENDED FORECAST TODAY...BUT NOT ANTICIPATING ANY MAJOR PRECIPITATION EVENTS. NORTHWEST FLOW MONDAY AND TUESDAY WILL BRING COOLER TEMPERATURES. THERE COULD BE A FEW MORE SHOWER(S) GENERATED TUESDAY AFTERNOON MAINLY ON THE CENTRAL COAST WITH A PASSING WEATHER DISTURBANCE. ANOTHER SYSTEM MOVES ACROSS THE GREAT BASIN ON WEDNESDAY BUT THIS LOOKS MORE LIKE A WIND EVENT FOR OUR REGION...INSIDE SLIDER. SOME LIGHT PRECIPITATION MAY MOVE ACROSS THE NORTH-FACING MOUNTAINS THEN. OFFSHORE FLOW RETURNS THURSDAY THEN TURNS BACK ONSHORE FRIDAY. OVERALL...NEXT WEEK WILL TURN OUT RATHER DRY WITH SOME BOUTS OF WIND AT TIMES.




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