Forecast Discussion

000
FXUS66 KSGX 062149
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
149 PM PST WED JAN 6 2016

.SYNOPSIS...
STORMY WEATHER CONTINUES THROUGH EARLY THURSDAY MORNING...WITH
PERIODS OF HEAVY RAINFALL...HEAVY SNOW IN THE MOUNTAINS ABOVE 4500
FEET...GUSTY WINDS IN THE COAST...MOUNTAIN AND DESERT REGIONS. SOME
THUNDERSTORMS MAY BE SEVERE. FLASH FLOODING...URBAN AND SMALL STREAM
FLOODING...AS WELL AS RIVER FLOODING AT THE SAN DIEGO RIVER COULD
OCCUR. DAMAGING SURF AND COASTAL FLOODING WILL BE POSSIBLE THURSDAY
INTO FRIDAY AT THE BEACHES. PERIODS OF SCATTERED LIGHTER SHOWERS FOR
LATER THURSDAY THROUGH SATURDAY. DRIER SUNDAY THROUGH EARLY NEXT
WEEK UNDER HIGHER PRESSURE ALOFT...THEN ANOTHER STORM-SYSTEM MAY
MOVE INTO THE REGION MID TO LATE NEXT WEEK.

&&

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

RIGHT NOW...RADAR IMAGERY SHOWS FAST MOVING MODERATE TO HEAVY
SHOWERS AND SCATTERED THUNDERSTORMS...SOME OF WHICH HAVE PRODUCED
STRONG WINDS...AND EVEN ONE REPORT OF A BRIEF TORNADO SOUTH OF SAN
CLEMENTE CITY. WATER VAPOR SATELLITE INDICATES A POTENT UPPER LEVEL
LOW OFF THE COAST OF THE PACIFIC NORTHWEST...WITH AN UPPER LEVEL JET
OVER SOUTHERN CALIFORNIA AND NORTHERN BAJA MEXICO. LOCAL WRF
FORECAST SOUNDINGS FOR THE COASTAL AREAS INDICATE STRONG LOW-LEVEL
SHEAR WITH CAPE VALUES REACHING 200-500 J/KG THIS AFTERNOON INTO THE
LATE NIGHT HOURS...AND THE SPC MESOANALYSIS SHOWS 50 KT OF SHEAR
OVER THE WATERS. AS A RESULT...SOME THUNDERSTORMS COULD BE
SEVERE...AND SPC HAS US IN A SLIGHT CHANCE IN THEIR DAY 1 CONVECTIVE
OUTLOOK. THESE ATMOSPHERIC PARAMETERS COULD EVEN BRING WATERSPOUT OR
MORE ISOLATED BRIEF TORNADOES TO THE COAST. FOR ADDITIONAL RAINFALL
AMOUNTS FROM THE STORM SYSTEM LATER TODAY INTO TOMORROW
MORNING...PLEASE SEE THE HYDROLOGY SECTION BELOW.

SNOW LEVEL IS CURRENTLY AT AROUND 5000 FEET...AND WILL HOVER AROUND
4500-5000 FEET TODAY...BEFORE LOWERING TO AROUND 4000 FEET LATE THIS
EVENING INTO THURSDAY MORNING. ADDITIONAL HEAVY SNOW IS LIKELY ABOVE
4500 FEET IN THE MOUNTAINS OF SAN BERNARDINO...RIVERSIDE AND SAN
DIEGO COUNTY MOUNTAINS...AND WINTER STORM WARNINGS ARE POSTED. WINDS
ARE ALSO PRETTY STRONG OUT OF THE WEST IN THE MOUNTAIN RIDGES AND
DESERT SLOPES...WITH SOME GUSTS IN THE 40-60 MPH BEING REPORTED.
WITH THE STRONG ONSHORE FLOW CONTINUING...EXPECT THOSE STRONG WINDS
TO CONTINUE THROUGH TONIGHT. ALSO...GUSTY WINDS ALONG THE COAST ARE
ALSO LIKELY THIS AFTERNOON AND EARLY EVENING AS THE COLD FRONT MOVES
THROUGH THE REGION...AND SO A WIND ADVISORY WILL BE IN EFFECT FOR
THE COASTAL AREAS...WITH GUSTS OF 40-50 MPH POSSIBLE.

COMPARATIVELY LIGHTER PERIODS OF SCATTERED SHOWERS WILL PREVAIL
LATER THURSDAY THROUGH FRIDAY...AND THEN A WEAK SYSTEM MAY BRING
MORE SHOWERS TO THE REGION ON SATURDAY. DRIER SUNDAY THROUGH EARLY
NEXT WEEK UNDER WEAK RIDGING ALOFT...WITH ANOTHER POSSIBLE STORM
SYSTEM MOVING INTO THE REGION AROUND MID-TO-LATE NEXT WEEK.

&&

.AVIATION...
061700Z... WIDESPREAD CIGS BELOW 2000 FEET MSL AND VIS
2-4 SM IN AREAS OF HEAVIER RAINFALL WILL CONTINUE THROUGH THIS
AFTERNOON. THUNDERSTORMS WILL BE EMBEDDED WITH THE HEAVIER
SHOWERS...AND MOVE FROM NW TO SE OVER LOCAL TAF SITES THROUGH AT
LEAST 03Z THURSDAY.
THE CIGS SHOULD INCREASE TO 2000 FT MSL OR HIGHER WITH VIS OF 3 SM
OR GREATER BETWEEN 03Z AND 07Z. AN ADDITIONAL ROUND OF SHOWERS IS
EXPECTED AFTER 07Z WITH PERIODS OF SUB 2000 FT MSL CIGS AND SUB 3 SM
VIS POSSIBLE THROUGH 16Z THURSDAY AT THE LOCAL TAF SITES.

&&

.MARINE...
130 PM...GUSTY SOUTH WINDS NEAR 20 KTS WITH GUSTS 25 TO 30 KTS WILL
DEVELOP OVER THE COASTAL WATERS THIS MORNING AND PERSIST INTO THIS
AFTERNOON. WINDS WILL TRANSITION TO A W OR SW DIRECTION THIS EVENING
AND REMAIN ELEVATED AT 15 TO 20 KTS WITH GUST 20 TO 25 KTS THROUGH
FRIDAY. HEAVY TO MODERATE RAIN AND PERIODS OF THUNDERSTORMS WILL
ALSO OCCUR THIS AFTERNOON AND OVERNIGHT. SEAS WILL CONTINUE TO
SLOWLY INCREASE INTO THE DAY ON THURSDAY. SEAS SHOULD BE 9 TO 12 FT
TODAY AND FRIDAY...WITH 11 TO 16 FT SEAS EXPECTED THURSDAY. SEE THE
SMALL CRAFT ADVISORY FOR ADDITIONAL DETAILS...LAXMWWSGX. WINDS AND
SEAS WILL DECREASE BY SATURDAY...BUT PERIODS OF SHOWER ACTIVITY WILL
REMAIN POSSIBLE INTO NEXT WEEK.

&&

.BEACHES...
130 PM...THE WEST SOUTHWEST SWELL THAT IS CURRENTLY BRINGING
WIDESPREAD 5-8 FT SURF AND LOCAL SETS TO 12 FT IN SOUTHERN SAN DIEGO
COUNTY WILL CONTINUE TO BUILD INTO THE DAY ON THURSDAY. GIVEN THE
EXPECTED BUILD UP IN THE SWELL...SURF SHOULD INCREASE TO 7-12 FT
WITH SETS NEAR 15 FT ALONG FAVORED WEST FACING BEACHES. HIGHEST SETS
ARE EXPECTED IN SAN DIEGO COUNTY. COASTAL FLOODING AND POTENTIAL
DAMAGE TO COASTAL STRUCTURES...SUCH AS PIERS...WILL BE POSSIBLE ON
THURSDAY. FOR ADDITIONAL DETAILS...SEE THE LAXCFWSGX. THE SURF WILL
REMAIN HIGH ON FRIDAY...WITH LOWER SURF EXPECTED OVER THE WEEKEND
INTO EARLY NEXT WEEK.

ALSO...LIGHTNING WILL BE POSSIBLE AT THE BEACHES THIS AFTERNOON INTO
LATE TONIGHT DUE TO THUNDERSTORMS MOVING OVER THE REGION. A BEACH
HAZARDS STATEMENT HAS BEEN ISSUED.

&&

.HYDROLOGY...
THE SAN DIEGO RIVER AT FASHION VALLEY IS CURRENTLY AT
8.7 FEET. THE LATEST FORECAST HAS THE RIVER REACHING FLOOD STAGE AT
10 PM THIS EVENING...CRESTING AT 11.9 FEET AT 4 AM THURSDAY.

ADDITIONAL RAINFALL THROUGH EARLY MORNING IS EXPECTED TO RANGE FROM
AROUND 1.5 TO 2.5 INCHES IN THE COAST AND VALLEYS...2 TO 5 INCHES IN
THE COASTAL SLOPES...1 TO 3 INCHES ON THE DESERT SLOPES...AND 0.5 TO
0.75 INCHES IN THE DESERTS. THIS IS EXPECTED TO PRODUCE MORE URBAN
AND SMALL STREAM FLOODING TODAY AND POSSIBLE FLASH FLOODING AND
DEBRIS FLOWS WHERE THUNDERSTORMS AND BANDS OF HEAVIER SHOWERS TRACK
ACROSS THE SAME AREA AND IN BURN AREAS DUE TO HIGH INTENSITY
RAINFALL. A FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH 11 AM
THURSDAY FOR AREAS OVER AND WEST OF THE MOUNTAINS BELOW 4000-5000
FOOT ELEVATION.

FOR LATER THURSDAY MORNING THROUGH FRIDAY...PRECIPITATION AMOUNTS
LOOK TO BE 0.15-0.50 INCHES IN ORANGE COUNTY COASTAL/INLAND AND THE
INLAND EMPIRE...0.50-1 INCH IN SAN DIEGO COUNTY COASTAL/INLAND...1-2
INCHES IN THE SAN DIEGO COUNTY MOUNTAINS...0.75-1.25 INCHES IN THE
SAN BERNARDINO COUNTY MOUNTAINS AND RIVERSIDE COUNTY MOUNTAINS...AND
A TRACE TO 0.15 INCHES IN THE DESERTS.

FOR LATE FRIDAY NIGHT THROUGH SATURDAY...PRECIPITATION AMOUNTS LOOK
TO BE 0.25-0.45 INCHES IN ORANGE COUNTY COASTAL/INLAND AND THE
INLAND EMPIRE...0.10-0.30 INCHES IN SAN DIEGO COUNTY COASTAL/INLAND
AND THE SAN DIEGO COUNTY MOUNTAINS...0.50-0.75 INCHES IN THE SAN
BERNARDINO COUNTY MOUNTAINS AND RIVERSIDE COUNTY MOUNTAINS...0.10-
0.20 INCHES IN THE HIGH DESERTS...AND A TRACE TO 0.10 INCHES IN THE
LOWER DESERTS.

&&

.SKYWARN...
SKYWARN ACTIVATION IS REQUESTED.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH THROUGH THURSDAY MORNING FOR ORANGE COUNTY
COASTAL AREAS-ORANGE COUNTY INLAND AREAS-RIVERSIDE COUNTY
MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN BERNARDINO
AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO
COUNTY COASTAL AREAS-SAN DIEGO COUNTY MOUNTAINS-SAN DIEGO
COUNTY VALLEYS-SAN GORGONIO PASS NEAR BANNING-SANTA ANA
MOUNTAINS AND FOOTHILLS.

WINTER STORM WARNING UNTIL 4 AM PST FRIDAY FOR SAN DIEGO COUNTY
MOUNTAINS.

WINTER STORM WARNING UNTIL 4 AM PST FRIDAY FOR RIVERSIDE COUNTY
MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS.

WIND ADVISORY UNTIL 6 PM PST THIS EVENING FOR ORANGE COUNTY
COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.

BEACH HAZARDS STATEMENT THROUGH THURSDAY MORNING FOR ORANGE
COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.

HIGH SURF WARNING UNTIL 10 PM PST FRIDAY FOR ORANGE COUNTY
COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.

PZ...SMALL CRAFT ADVISORY UNTIL 4 PM PST FRIDAY FOR COASTAL WATERS
FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT TO 30 NM-
WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING
30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND.

&&

$$

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