Small Craft Advisory 12, NWS San Diego, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
100 PM PST SUN DEC 14 2014

.SYNOPSIS...
FAIR...AND A LITTLE WARMER THROUGH MONDAY UNDER A WEAK HIGH PRESSURE
RIDGE ALOFT. INCREASING HIGH CLOUDS ON MONDAY AS A LOW PRESSURE
TROUGH APPROACHES FROM THE WEST. THE TROUGH WILL BE WEAKENING...BUT
STILL IS EXPECTED TO PRODUCE SOME LIGHT PRECIPITATION ON TUESDAY. A
COLDER TROUGH WILL FOLLOW FOR WEDNESDAY WITH A CHANCE FOR HEAVIER
RAIN AND SNOW SHOWERS...AND EVEN A FEW THUNDERSTORMS. COOL THROUGH
THURSDAY WITH SHOWERS ENDING...FOLLOWED BY DRY AND WARMER WEATHER
FOR FRIDAY. THERE IS ANOTHER CHANCE FOR SHOWERS OVER THE WEEKEND...
THEN DRY...WITH OFFSHORE FLOW TO FOLLOW EARLY NEXT WEEK.

&&

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

TEMPERATURES WERE SLOWLY CLIMBING THROUGH THE 50S INTO THE LOWER 60S
AT MIDDAY UNDER SUNNY SKIES. SURFACE GRADIENTS WERE VERY WEAK AND
WINDS WERE LIGHT.

FAIR AND NOT QUITE AS COLD OVERNIGHT AS HIGH CLOUDS SPREAD ACROSS
THE REGION FROM THE WEST. THE HIGH CLOUDS MAY DIM THE SUN AT TIMES
TOMORROW WHICH WILL KEEP DAYTIME HIGHS IN THE 50S AND 60S AT LOWER
ELEVATIONS.

A WEAK RIDGE ALOFT WILL DRIFT OVER THE REGION THROUGH EARLY MON...
KEEPING WINDS LIGHT AND THE SKIES GENERALLY FAIR. AS THE RIDGE AXIS
DRIFTS EAST EARLY MON...HIGH CLOUDS WILL THICKEN AND LOWER AHEAD OF
A SHORT WAVE TROUGH OVER THE EASTPAC. THIS SYSTEM IS FORECAST TO
WEAKEN AS IT SLIDES EAST ACROSS SOCAL...BUT LOOKS SUBSTANTIAL ENOUGH
TO GENERATE...LIGHT RAIN AND SHOWERS ON TUE. A COLDER SHORTWAVE
FOLLOWS FOR WED...BUT THE VARIOUS MODEL RUNS HAVE GENERATED
DIFFERING SOLUTIONS...MAKING CONFIDENCE LOWER FOR TIMING AND
INTENSITY. A BLEND OF SOLUTIONS SUGGESTS IT WILL BE STRONGER AND
SLIDE SE...JUST INSIDE THE CA COASTLINE. WITH AN INCH OF PW OFFSHORE
TO INGEST...THE COMBINATION OF JET DYNAMICS AND COLD AIR ALOFT WILL
SUPPORT A PERIOD OF HEAVY SHOWERS AT SOME POINT ON WED.
THUNDERSTORMS ARE POSSIBLE AS WELL...WHICH COULD HAVE HEAVY
DOWNPOURS WITH BRIEF...HIGH RAINFALL RATES.

THE MODELS ALL SHOW A SECONDARY SHORT WAVE HELPING TO DIG THIS
SYSTEM A BIT MORE AND SLOW IT DOWN WHICH WILL SPILL THE SHOWER
THREAT OVER INTO THU. FAIR AND A BIT WARMER ON FRI UNDER ANOTHER
WEAK SHORTWAVE RIDGE...FOLLOWED BY ANOTHER TROUGH NEXT WEEKEND. THE
TROUGH IS STRONGER WITH MORE WIDESPREAD PRECIP ON THE 12Z ECMWF
RUN...BUT VERY LITTLE IS GENERATED BY THE 12Z GFS. SO...JUST A
CHANCE OF SHOWERS...THEN BOTH OF THE LATEST GFS/EC RUNS SHOW
POSSIBLE STRONG OFFSHORE FLOW DEVELOPING ACROSS SOCAL AS A RIDGING
REEMERGES OVER THE EASTPAC AND NOSES EAST ACROSS THE PACNW.

DAYTIME TEMPERATURES ARE EXPECTED TO REMAIN BELOW AVERAGE THIS WEEK
WITH THE COLDEST DAYS TUE THROUGH THU. WARMER BY FRI.

&&

.HYDROLOGY...
FOR THE INITIAL SHORTWAVE AND WEAKENING FRONT ON TUE...EXPECT SOME
SHOWERS TO ARRIVE ACROSS ORANGE AND SAN BERNARDINO COUNTIES EARLY
TUE MORNING..AND SPREAD SOUTH THROUGH SAN DIEGO COUNTY THROUGH
MIDDAY. OROGRAPHIC EFFECTS LOOK MARGINAL...SO PRELIMINARY RAINFALL
ESTIMATES ARE FOR ONE-HALF TO ONE INCH IN THE SAN BERNARDINO
MTS...WITH AROUND ONE-QUARTER TO NEAR ONE-HALF INCH FARTHER SOUTH
THROUGH EARLY EVENING. THE SNOW LEVEL IS EXPECTED TO BE BETWEEN 5500
AND 6000 FEET WITH SEVERAL INCHES OF SNOW POSSIBLE ON THE HIGHER
PEAKS OF THE SAN JACINTO AND SAN BERNARDINO MTS.

SCATTERED...LIGHT SHOWERS MAY CONTINUE TUE NIGHT INTO EARLY WED
MORNING AHEAD OF THE COLDER TROUGH...THEN EXPECT RAIN/SNOW SHOWERS
TO INCREASE AGAIN LATE TUE NIGHT AND WED. THIS EVENT WILL BE MORE
CONVECTIVE...SO RAIN AND SNOWFALL WILL BE MORE VARIABLE...BUT THERE
IS A POTENTIAL FOR AN ADDITIONAL INCH OR MORE OF RAIN MOST AREAS
ALONG AND WEST OF THE MTS BY THU MORNING...AND HEAVY SNOW ABOVE 5000
FT. CONFIDENCE REMAINS LOW TO MODERATE WITH THIS EVENT DUE TO
UNCERTAINTY ASSOCIATED WITH THE STRENGTH AND TRACK OF THE UPPER LOW.
AVAILABLE PW WILL AGAIN BE CLOSE TO ONE INCH...SO MOISTURE WILL BE
SUFFICIENT. INSTABILITY PARAMETERS SUGGEST THERE IS A THREAT OF
ISOLATED THUNDERSTORMS LATE TUE NIGHT INTO WED EVENING AS WELL. THE
SHOWERS ARE EXPECTED TO END THU MORNING.

&&

.AVIATION...
142036Z...CHANCE THAT SOME GROUND FOG COULD FORM IN THE VALLEYS
DURING THE 15/0300-1500 UTC TIME-FRAME...PRODUCING LOCAL VIS AOB 1
SM. CHANCES ARE LOW THAT FOG WILL IMPACT KSAN...KCRQ...KSNA AND
KONT. OTHERWISE...UNRESTRICTED VIS THROUGH MONDAY MORNING...WITH SCT
CLOUDS AOA 20000 FT MSL BECOMING BKN BY 15/0300 UTC.

&&

.MARINE...
1236 PM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH MONDAY
AFTERNOON. SOUTH WINDS WILL BEGIN TO INCREASE MONDAY EVENING AHEAD
OF A COLD FRONT. LATEST RUN OF THE LOCAL WRF INDICATES SUSTAINED 20
KT SOUTHERLY WINDS OVER THE COASTAL WATERS LATE MONDAY NIGHT/EARLY
TUESDAY MORNING AS THE FRONT MOVES THROUGH...WHICH WOULD MEAN THAT
25-30 KT GUSTS ARE LIKELY. ANOTHER TROUGH MOVING INTO THE AREA EARLY
WEDNESDAY MORNING WILL RESULT IN STRONG WINDS AGAIN OVER THE WATERS.
ALSO...COMBINED SEAS WILL AGAIN APPROACH 10 FEET MONDAY NIGHT
THROUGH TUESDAY EVENING AS ANOTHER LARGE WEST SWELL MOVES IN. A
SMALL CRAFT ADVISORY ISSUANCE WILL LIKELY BE NECESSARY.

&&

.BEACHES...
1236 PM...BUOY REPORTS SHOW THAT THE WEST SWELL CONTINUES TO SLOWLY
FADE THIS MORNING...AS IT IS NOW AT AROUND 6 FEET/14 SECONDS AT THE
SAN CLEMENTE BASIN BUOY...AND 4-6 FEET/13-15 SECONDS AT THE
NEARSHORE CDIP BUOYS. THE SWELL WILL CONTINUE TO DIMINISH TODAY INTO
EARLY MONDAY...BUT STILL BE HIGH ENOUGH TO BRING SURF OF 3-6 FEET
WITH LOCAL SETS TO 7 FEET TO THE WEST FACING BEACHES THROUGH EARLY
MONDAY. STRONG RIP CURRENTS ARE POSSIBLE AT ALL BEACHES THROUGH THE
WEEK...AND A BEACH HAZARDS STATEMENT IS IN EFFECT. ANOTHER
LARGE...LONG PERIOD WEST-NORTHWEST SWELL GENERATED BY A STRONG STORM
OVER THE WEST PACIFIC WILL ARRIVE MONDAY MORNING...BUILD MONDAY
NIGHT AND PEAK TUESDAY AT 10-11 FEET/16-17 SECONDS...LIKELY BRINGING
HIGH SURF OF 5 TO 8 FEET AND LOCAL 10 FOOT SETS FOR LATE MONDAY INTO
TUESDAY. SWELL AND SURF WILL BEGIN TO SUBSIDE LATE TUESDAY.

&&

.SKYWARN...
SKYWARN ACTIVATION WILL NOT BE NEEDED TODAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...BEACH HAZARDS STATEMENT THROUGH MONDAY AFTERNOON FOR THE ORANGE
     COUNTY COASTAL AREAS AND SAN DIEGO COUNTY COASTAL AREAS.

PZ...NONE.

&&

PUBLIC/HYDROLOGY...JAD
AVIATION/MARINE/BEACHES...HARRISON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN DIEGO CA
349 PM PST SUN DEC 14 2014

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1100 AM     DEBRIS FLOW      5 WSW LAKELAND VILLAGE  33.61N 117.43W
12/14/2014                   RIVERSIDE          CA   DEPT OF HIGHWAYS

            ROCKSLIDE ALONG CA HIGHWAY 74 REQUIRING A
            ROAD CLOSURE FROM CASPERS PARK ROAD TO
            NICHOLS ROAD...BOULDERS 5+ FEET IN DIAMETER
            REPORTED BY CHP.

&&

BA