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000
FXUS66 KLOX 202337 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
437 PM PDT WED AUG 20 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

THERE IS A SLIGHT CHANCE OF THUNDERSTORMS THIS EVENING IN LOS
ANGELES COUNTY AND IN THE VENTURA COUNTY MOUNTAINS. THERE IS A
SLIGHT CHANCE OF THUNDERSTORMS TOMORROW AS WELL BUT PRIMARILY IN THE
MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES. AFTERNOON HIGH
TEMPERATURES WILL BE BELOW NORMAL THROUGH THE END OF THE WEEK WITH
LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS. CLEARER SKIES
AND WARMER TEMPERATURES ARE EXPECTED FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
THE UPPER LOW PRESSURE CENTERED JUST OFF THE LOS ANGELES COUNTY
COAST THIS AFTERNOON WILL SLOWLY DROP A BIT FARTHER SOUTH TONIGHT
THEN BEGIN TO EJECT EASTWARD TOMORROW.  THIS IS THE SYSTEM
RESPONSIBLE FOR SPINNING UP THE LINE OF THUNDERSTORMS SOUTHEAST OF
THE SERVICE AREA THIS MORNING AND AS IT SHIFTS... THE FLOW OF
PRECIPITABLE WATER WILL CRANK AROUND TO THE EAST AND NORTHEAST.
THIS WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS INTO LOS ANGELES
COUNTY BY LATE THIS AFTERNOON.

GOOD INSTABILITY ACROSS THE SERVICE AREA WILL ENCOURAGE SOME
CONVECTIVE DEVELOPMENT WITH THE PROPER WIND FLOW.  HOWEVER A LACK OF
MOISTURE WILL KEEP DEVELOPMENT TO A MINIMAL LEVEL UNLESS AND UNTIL
THE LOW CENTER SHIFTS ENOUGH TO TIGHTEN THE GRADIENTS AND REALLY
PULL THE MOISTURE AROUND THE SYSTEM.  KEEPING A SLIGHT CHANCE OF
THUNDERSTORMS IN LOS ANGELES COUNTY AND IN THE VENTURA COUNTY
MOUNTAINS THIS AFTERNOON AND TONIGHT... BUT AM NOT EXPECTING MUCH IF
ANY PRECIPITATION.  WIND FROM DOWNDRAFTS AND DRY LIGHTNING ARE THE
PRIMARY CONCERNS.

BY TOMORROW THE LOW WILL HAVE SHIFTED TO THE SOUTHEAST AND A BETTER
PULL OF MOISTURE IS POSSIBLE THOUGH THE INSTABILITY IS SOMEWHAT
REDUCED.  THIS SHOULD KEEP ANY THUNDERSTORM DEVELOPMENT IN THE
VICINITY OF THE MOUNTAINS BUT ALL THINGS CONSIDERED IT IS A BETTER
SITUATION TO SQUEEZE OUT A LITTLE PRECIP IN THE SAN GABRIEL RANGE.
OTHER LOCATIONS HAVE A CHANCE OF DOWNDRAFTS AND DRY LIGHTNING MUCH
LIKE TODAY.

COASTAL LOW CLOUDS WILL CONTINUE THROUGH THE NEXT FEW DAYS AND WILL
CONTINUE TO PUSH WELL INLAND IN THE ADJACENT VALLEYS.  FRIDAY WILL
SEE A REDUCED THREAT OF CONVECTIVE WEATHER BUT THE MARINE CLOUDS
WILL KEEP HIGH TEMPERATURES REDUCED DUE TO LINGERING LOW CLOUDS.

.LONG TERM (SAT-TUE)...
A MIXED BAG THROUGH THE WEEKEND AND INTO NEXT WEEK.  HIGH PRESSURE
TRIES TO BUILD OVER THE AREA AND LOOKS TO BE EFFECTIVE IN KEEPING
THE NEXT LOW TO THE NORTH OF THE REGION.  GENERALLY... TEMPERATURES
WILL HOVER NEAR NORMAL READINGS AND THE MARINE CLOUDS WILL COME IN
ALONG THE COAST BUT NOT VERY FAR INLAND.  NO CONVECTIVE DEVELOPMENT
NOR STRONG WINDS ARE EXPECTED AT THIS TIME.

&&

.AVIATION...20/2337Z.

LOWER CONFIDENCE IS PACKAGE THAN PREVIOUSLY THOUGHT AS VFR
CONDITIONS HAVE DEVELOPED AT ALL TERMINALS THIS AFTERNOON. IFR TO
MVFR CONDITIONS WILL LIKELY RETURN BETWEEN 03Z AND 08Z. THERE IS A
CHANCE OF LIFR CONDITIONS BETWEEN 10Z AND 16Z AT TERMINALS NORTH OF
POINT CONCEPTION. THERE IS A 20 PERCENT CHANCE OF THUNDERSTORMS FOR
KPMD AND KWJF THROUGH 04Z.

KLAX...THERE IS A 80 PERCENT CHANCE OF MVFR CONDITIONS REDEVELOPING
BETWEEN 03Z AND 08Z. MVFR CONDITIONS SHOULD REMAIN AT KLAX THROUGH
AT 16Z...OR 18Z AT THE LATEST.

KBUR...THERE IS A 60 PERCENT CHANCE OF MVFR CONDITIONS...MAINLY
AFTER 07Z. VFR CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND 17Z.

&&

.MARINE...20/200 PM.

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&
$$

PUBLIC...KJ
AVIATION...SWEET
MARINE...SWEET

WWW.WEATHER.GOV/LOSANGELES











000
FXUS66 KLOX 202337 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
437 PM PDT WED AUG 20 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

THERE IS A SLIGHT CHANCE OF THUNDERSTORMS THIS EVENING IN LOS
ANGELES COUNTY AND IN THE VENTURA COUNTY MOUNTAINS. THERE IS A
SLIGHT CHANCE OF THUNDERSTORMS TOMORROW AS WELL BUT PRIMARILY IN THE
MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES. AFTERNOON HIGH
TEMPERATURES WILL BE BELOW NORMAL THROUGH THE END OF THE WEEK WITH
LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS. CLEARER SKIES
AND WARMER TEMPERATURES ARE EXPECTED FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
THE UPPER LOW PRESSURE CENTERED JUST OFF THE LOS ANGELES COUNTY
COAST THIS AFTERNOON WILL SLOWLY DROP A BIT FARTHER SOUTH TONIGHT
THEN BEGIN TO EJECT EASTWARD TOMORROW.  THIS IS THE SYSTEM
RESPONSIBLE FOR SPINNING UP THE LINE OF THUNDERSTORMS SOUTHEAST OF
THE SERVICE AREA THIS MORNING AND AS IT SHIFTS... THE FLOW OF
PRECIPITABLE WATER WILL CRANK AROUND TO THE EAST AND NORTHEAST.
THIS WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS INTO LOS ANGELES
COUNTY BY LATE THIS AFTERNOON.

GOOD INSTABILITY ACROSS THE SERVICE AREA WILL ENCOURAGE SOME
CONVECTIVE DEVELOPMENT WITH THE PROPER WIND FLOW.  HOWEVER A LACK OF
MOISTURE WILL KEEP DEVELOPMENT TO A MINIMAL LEVEL UNLESS AND UNTIL
THE LOW CENTER SHIFTS ENOUGH TO TIGHTEN THE GRADIENTS AND REALLY
PULL THE MOISTURE AROUND THE SYSTEM.  KEEPING A SLIGHT CHANCE OF
THUNDERSTORMS IN LOS ANGELES COUNTY AND IN THE VENTURA COUNTY
MOUNTAINS THIS AFTERNOON AND TONIGHT... BUT AM NOT EXPECTING MUCH IF
ANY PRECIPITATION.  WIND FROM DOWNDRAFTS AND DRY LIGHTNING ARE THE
PRIMARY CONCERNS.

BY TOMORROW THE LOW WILL HAVE SHIFTED TO THE SOUTHEAST AND A BETTER
PULL OF MOISTURE IS POSSIBLE THOUGH THE INSTABILITY IS SOMEWHAT
REDUCED.  THIS SHOULD KEEP ANY THUNDERSTORM DEVELOPMENT IN THE
VICINITY OF THE MOUNTAINS BUT ALL THINGS CONSIDERED IT IS A BETTER
SITUATION TO SQUEEZE OUT A LITTLE PRECIP IN THE SAN GABRIEL RANGE.
OTHER LOCATIONS HAVE A CHANCE OF DOWNDRAFTS AND DRY LIGHTNING MUCH
LIKE TODAY.

COASTAL LOW CLOUDS WILL CONTINUE THROUGH THE NEXT FEW DAYS AND WILL
CONTINUE TO PUSH WELL INLAND IN THE ADJACENT VALLEYS.  FRIDAY WILL
SEE A REDUCED THREAT OF CONVECTIVE WEATHER BUT THE MARINE CLOUDS
WILL KEEP HIGH TEMPERATURES REDUCED DUE TO LINGERING LOW CLOUDS.

.LONG TERM (SAT-TUE)...
A MIXED BAG THROUGH THE WEEKEND AND INTO NEXT WEEK.  HIGH PRESSURE
TRIES TO BUILD OVER THE AREA AND LOOKS TO BE EFFECTIVE IN KEEPING
THE NEXT LOW TO THE NORTH OF THE REGION.  GENERALLY... TEMPERATURES
WILL HOVER NEAR NORMAL READINGS AND THE MARINE CLOUDS WILL COME IN
ALONG THE COAST BUT NOT VERY FAR INLAND.  NO CONVECTIVE DEVELOPMENT
NOR STRONG WINDS ARE EXPECTED AT THIS TIME.

&&

.AVIATION...20/2337Z.

LOWER CONFIDENCE IS PACKAGE THAN PREVIOUSLY THOUGHT AS VFR
CONDITIONS HAVE DEVELOPED AT ALL TERMINALS THIS AFTERNOON. IFR TO
MVFR CONDITIONS WILL LIKELY RETURN BETWEEN 03Z AND 08Z. THERE IS A
CHANCE OF LIFR CONDITIONS BETWEEN 10Z AND 16Z AT TERMINALS NORTH OF
POINT CONCEPTION. THERE IS A 20 PERCENT CHANCE OF THUNDERSTORMS FOR
KPMD AND KWJF THROUGH 04Z.

KLAX...THERE IS A 80 PERCENT CHANCE OF MVFR CONDITIONS REDEVELOPING
BETWEEN 03Z AND 08Z. MVFR CONDITIONS SHOULD REMAIN AT KLAX THROUGH
AT 16Z...OR 18Z AT THE LATEST.

KBUR...THERE IS A 60 PERCENT CHANCE OF MVFR CONDITIONS...MAINLY
AFTER 07Z. VFR CONDITIONS SHOULD REDEVELOP BETWEEN 16Z AND 17Z.

&&

.MARINE...20/200 PM.

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&
$$

PUBLIC...KJ
AVIATION...SWEET
MARINE...SWEET

WWW.WEATHER.GOV/LOSANGELES










000
FXUS66 KLOX 202102
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
150 PM PDT WED AUG 20 2014

.SYNOPSIS...

THERE IS A SLIGHT CHANCE OF THUNDERSTORMS THIS EVENING IN LOS
ANGELES COUNTY AND IN THE VENTURA COUNTY MOUNTAINS. THERE IS A
SLIGHT CHANCE OF THUNDERSTORMS TOMORROW AS WELL BUT PRIMARILY IN THE
MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES. AFTERNOON HIGH
TEMPERATURES WILL BE BELOW NORMAL THROUGH THE END OF THE WEEK WITH
LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS. CLEARER SKIES
AND WARMER TEMPERATURES ARE EXPECTED FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
THE UPPER LOW PRESSURE CENTERED JUST OFF THE LOS ANGELES COUNTY
COAST THIS AFTERNOON WILL SLOWLY DROP A BIT FARTHER SOUTH TONIGHT
THEN BEGIN TO EJECT EASTWARD TOMORROW.  THIS IS THE SYSTEM
RESPONSIBLE FOR SPINNING UP THE LINE OF THUNDERSTORMS SOUTHEAST OF
THE SERVICE AREA THIS MORNING AND AS IT SHIFTS... THE FLOW OF
PRECIPITABLE WATER WILL CRANK AROUND TO THE EAST AND NORTHEAST.
THIS WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS INTO LOS ANGELES
COUNTY BY LATE THIS AFTERNOON.

GOOD INSTABILITY ACROSS THE SERVICE AREA WILL ENCOURAGE SOME
CONVECTIVE DEVELOPMENT WITH THE PROPER WIND FLOW.  HOWEVER A LACK OF
MOISTURE WILL KEEP DEVELOPMENT TO A MINIMAL LEVEL UNLESS AND UNTIL
THE LOW CENTER SHIFTS ENOUGH TO TIGHTEN THE GRADIENTS AND REALLY
PULL THE MOISTURE AROUND THE SYSTEM.  KEEPING A LSIGHT CHANCE OF
THUNDERSTORMS IN LOS ANGELES COUNTY AND IN THE VENTURA COUNTY
MOUNTAINS THIS AFTERNOON AND TONIGHT... BUT AM NOT EXPECTING MUCH IF
ANY PRECIPITATION.  WIND FROM DOWNDRAFTS AND DRY LIGHTNING ARE THE
PRIMARY CONCERNS.

BY TOMORROW THE LOW WILL HAVE SHIFTED TO THE SOUTHEAST AND A BETTER
PULL OF MOISTURE IS POSSIBLE THOUGH THE INSTABILITY IS SOMEWHAT
REDUCED.  THIS SHOULD KEEP ANY THUNDERSTORM DEVELOPMENT IN THE
VICINITY OF THE MOUNTAINS BUT ALL THINGS CONSIDERED IT IS A BETTER
SITUATION TO SQUEEZE OUT A LITTLE PRECIP IN THE SAN GABRIEL RANGE.
OTHER LOCATIONS HAVE A CHANCE OF DOWNDRAFTS AND DRY LIGHTNING MUCH
LIKE TODAY.

COASTAL LOW CLOUDS WILL CONTINUE THROUGH THE NEXT FEW DAYS AND WILL
CONTINUE TO PUSH WELL INLAND IN THE ADJACENT VALLEYS.  FRIDAY WILL
SEE A REDUCED THREAT OF CONVECTIVE WEATHER BUT THE MARINE CLOUDS
WILL KEEP HIGH TEMPERATURES REDUCED DUE TO LINGERING LOW CLOUDS.

.LONG TERM (SAT-TUE)...
A MIXED BAG THROUGH THE WEEKEND AND INTO NEXT WEEK.  HIGH PRESSURE
TRIES TO BUILD OVER THE AREA AND LOOKS TO BE EFFECTIVE IN KEEPING
THE NEXT LOW TO THE NORTH OF THE REGION.  GENERALLY... TEMPERATURES
WILL HOVER NEAR NORMAL READINGS AND THE MARINE CLOUDS WILL COME IN
ALONG THE COAST BUT NOT VERY FAR INLAND.  NO CONVECTIVE DEVELOPMENT
NOR STRONG WINDS ARE EXPECTED AT THIS TIME.

&&

.AVIATION...20/1800Z.
A COOL DISTURBANCE ALOFT HAS MANAGED TO KEEP A LINE OF THUNDERSTORMS
GOING JUST SOUTH OF OUR FORECAST AREA...BUT SO FAR THERE HAS BEEN NO
EFFECT ON OUR FORECAST DISTRICT. THERE IS A CONTINUED CHANCE OF
THUNDERSTORM ACTIVITY IN THE DESERT TAFS AND IT IS MENTIONED IN THE
KPMD AND KWJF TAFS. OTHERWISE...EXPECTING A RETURN OF THE MARINE
CLOUDS TONIGHT INTO THURSDAY MORNING WITH A MARINE LAYER DEPTH OF
AROUND 3000 FEET SOUTH WITH SOME SHALLOWING POSSIBLE NORTH OF POINT
CONCEPTION AND MVFR TO VFR CEILINGS. THERE IS A SLIGHT CHANCE THAT
THE MARINE CLOUDS WILL NOT DEVELOP AT EXPECTED.

KLAX AND KBUR...GOOD CONFIDENCE IN THE 18Z TAFS. THERE IS A 20
PERCENT CHANCE OF VFR CONDITIONS THROUGH THURSDAY.

&&

.MARINE...20/200 PM...

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&
$$

PUBLIC...KJ
AVIATION...SWEET
MARINE...SWEET

WWW.WEATHER.GOV/LOSANGELES








000
FXUS66 KLOX 202102
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
150 PM PDT WED AUG 20 2014

.SYNOPSIS...

THERE IS A SLIGHT CHANCE OF THUNDERSTORMS THIS EVENING IN LOS
ANGELES COUNTY AND IN THE VENTURA COUNTY MOUNTAINS. THERE IS A
SLIGHT CHANCE OF THUNDERSTORMS TOMORROW AS WELL BUT PRIMARILY IN THE
MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES. AFTERNOON HIGH
TEMPERATURES WILL BE BELOW NORMAL THROUGH THE END OF THE WEEK WITH
LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS. CLEARER SKIES
AND WARMER TEMPERATURES ARE EXPECTED FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
THE UPPER LOW PRESSURE CENTERED JUST OFF THE LOS ANGELES COUNTY
COAST THIS AFTERNOON WILL SLOWLY DROP A BIT FARTHER SOUTH TONIGHT
THEN BEGIN TO EJECT EASTWARD TOMORROW.  THIS IS THE SYSTEM
RESPONSIBLE FOR SPINNING UP THE LINE OF THUNDERSTORMS SOUTHEAST OF
THE SERVICE AREA THIS MORNING AND AS IT SHIFTS... THE FLOW OF
PRECIPITABLE WATER WILL CRANK AROUND TO THE EAST AND NORTHEAST.
THIS WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS INTO LOS ANGELES
COUNTY BY LATE THIS AFTERNOON.

GOOD INSTABILITY ACROSS THE SERVICE AREA WILL ENCOURAGE SOME
CONVECTIVE DEVELOPMENT WITH THE PROPER WIND FLOW.  HOWEVER A LACK OF
MOISTURE WILL KEEP DEVELOPMENT TO A MINIMAL LEVEL UNLESS AND UNTIL
THE LOW CENTER SHIFTS ENOUGH TO TIGHTEN THE GRADIENTS AND REALLY
PULL THE MOISTURE AROUND THE SYSTEM.  KEEPING A LSIGHT CHANCE OF
THUNDERSTORMS IN LOS ANGELES COUNTY AND IN THE VENTURA COUNTY
MOUNTAINS THIS AFTERNOON AND TONIGHT... BUT AM NOT EXPECTING MUCH IF
ANY PRECIPITATION.  WIND FROM DOWNDRAFTS AND DRY LIGHTNING ARE THE
PRIMARY CONCERNS.

BY TOMORROW THE LOW WILL HAVE SHIFTED TO THE SOUTHEAST AND A BETTER
PULL OF MOISTURE IS POSSIBLE THOUGH THE INSTABILITY IS SOMEWHAT
REDUCED.  THIS SHOULD KEEP ANY THUNDERSTORM DEVELOPMENT IN THE
VICINITY OF THE MOUNTAINS BUT ALL THINGS CONSIDERED IT IS A BETTER
SITUATION TO SQUEEZE OUT A LITTLE PRECIP IN THE SAN GABRIEL RANGE.
OTHER LOCATIONS HAVE A CHANCE OF DOWNDRAFTS AND DRY LIGHTNING MUCH
LIKE TODAY.

COASTAL LOW CLOUDS WILL CONTINUE THROUGH THE NEXT FEW DAYS AND WILL
CONTINUE TO PUSH WELL INLAND IN THE ADJACENT VALLEYS.  FRIDAY WILL
SEE A REDUCED THREAT OF CONVECTIVE WEATHER BUT THE MARINE CLOUDS
WILL KEEP HIGH TEMPERATURES REDUCED DUE TO LINGERING LOW CLOUDS.

.LONG TERM (SAT-TUE)...
A MIXED BAG THROUGH THE WEEKEND AND INTO NEXT WEEK.  HIGH PRESSURE
TRIES TO BUILD OVER THE AREA AND LOOKS TO BE EFFECTIVE IN KEEPING
THE NEXT LOW TO THE NORTH OF THE REGION.  GENERALLY... TEMPERATURES
WILL HOVER NEAR NORMAL READINGS AND THE MARINE CLOUDS WILL COME IN
ALONG THE COAST BUT NOT VERY FAR INLAND.  NO CONVECTIVE DEVELOPMENT
NOR STRONG WINDS ARE EXPECTED AT THIS TIME.

&&

.AVIATION...20/1800Z.
A COOL DISTURBANCE ALOFT HAS MANAGED TO KEEP A LINE OF THUNDERSTORMS
GOING JUST SOUTH OF OUR FORECAST AREA...BUT SO FAR THERE HAS BEEN NO
EFFECT ON OUR FORECAST DISTRICT. THERE IS A CONTINUED CHANCE OF
THUNDERSTORM ACTIVITY IN THE DESERT TAFS AND IT IS MENTIONED IN THE
KPMD AND KWJF TAFS. OTHERWISE...EXPECTING A RETURN OF THE MARINE
CLOUDS TONIGHT INTO THURSDAY MORNING WITH A MARINE LAYER DEPTH OF
AROUND 3000 FEET SOUTH WITH SOME SHALLOWING POSSIBLE NORTH OF POINT
CONCEPTION AND MVFR TO VFR CEILINGS. THERE IS A SLIGHT CHANCE THAT
THE MARINE CLOUDS WILL NOT DEVELOP AT EXPECTED.

KLAX AND KBUR...GOOD CONFIDENCE IN THE 18Z TAFS. THERE IS A 20
PERCENT CHANCE OF VFR CONDITIONS THROUGH THURSDAY.

&&

.MARINE...20/200 PM...

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&
$$

PUBLIC...KJ
AVIATION...SWEET
MARINE...SWEET

WWW.WEATHER.GOV/LOSANGELES







000
FXUS66 KLOX 201833
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1130 AM PDT WED AUG 20 2014

...NEW AVIATION DISCUSSION...

.SYNOPSIS...

A SLIGHT CHANCE OF THUNDERSTORMS TODAY IN LOS ANGELES COUNTY AND IN
THE VENTURA COUNTY MOUNTAINS. A SLIGHT CHANCE OF THUNDERSTORMS
TOMORROW IN THE LOS ANGELES AND VENTURA COUNTY MOUNTAINS AND THE
ANTELOPE VALLEY. AFTERNOON HIGHS BELOW NORMAL THROUGH THE END OF THE
WEEK WITH LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS.
CLEARER SKIES AND WARMER TEMPERATURES ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
*** MID-MORNING DISCUSSION UPDATE ***
BIG QUESTION TODAY WILL BE WHETHER AND WHEN THUNDERSTORMS SLIDE INTO
LOS ANGELES COUNTY TODAY AND IF ANY DEVELOPMENT MAKES IT INTO THE
VENTURA COUNTY MOUNTAINS AS WELL.  THE PRIMARY RAIN BAND CONTINUES
TO SLIDE SOUTHEASTWARD ACROSS SAN DIEGO... RIVERSIDE... AND SAN
BERNARDINO COUNTIES THIS MORNING.  HOWEVER AS THE CENTER OF THE LOW
DROPS SOUTHWARD INDICATES CONTINUE TO SHOW A LIKELIHOOD OF THE
THUNDERSTORM BAND WRAPPING AROUND INTO LOS ANGELES COUNTY THIS
AFTERNOON.  WITH GOOD INSTABILITY STRINGING ACROSS THE REGION INTO
THE MOUNTAINS OF SAN LUIS OBISPO COUNTY IT APPEARS THAT DEVELOPMENT
WILL NOT BE A PROBLEM BUT THE BEST MOISTURE APPEARS TO STAY TO THE
SOUTHEAST SO THIS COULD BE A LIMITING FACTOR ESPECIALLY FOR ANYTHING
WEST OF THE SAN GABRIEL RANGE.  LOOKS BETTER TOMORROW... BUT THEN
THE LOW MAY BE OUT OF POSITION.

NOT ANTICIPATING ANY NOTABLE CHANGES TO THE FORECAST PACKAGE AT THIS
TIME OTHER THAN POSSIBLE TWEAKING FOR THUNDERSTORM DEVELOPMENT TODAY
AND TOMORROW.

*** EARLY MORNING DISCUSSION ***
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...20/1800Z.
A COOL DISTURBANCE ALOFT HAS MANAGED TO KEEP A LINE OF THUNDERSTORMS
GOING JUST SOUTH OF OUR FORECAST AREA...BUT SO FAR THERE HAS BEEN NO
EFFECT ON OUR FORECAST DISTRICT. THERE IS A CONTINUED CHANCE OF
THUNDERSTORM ACTIVITY IN THE DESERT TAFS AND IT IS MENTIONED IN THE
KPMD AND KWJF TAFS. OTHERWISE...EXPECTING A RETURN OF THE MARINE
CLOUDS TONIGHT INTO THURSDAY MORNING WITH A MARINE LAYER DEPTH OF
AROUND 3000 FEET SOUTH WITH SOME SHALLOWING POSSIBLE NORTH OF POINT
CONCEPTION AND MVFR TO VFR CEILINGS. THERE IS A SLIGHT CHANCE THAT
THE MARINE CLOUDS WILL NOT DEVELOP AT EXPECTED.

KLAX AND KBUR...GOOD CONFIDENCE IN THE 18Z TAFS. THERE IS A 20
PERCENT CHANCE OF VFR CONDITIONS THROUGH THURSDAY.

&&

.MARINE...20/900 AM...

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE/KJ
AVIATION...SWEET
MARINE...SWEET
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES















000
FXUS66 KLOX 201833
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1130 AM PDT WED AUG 20 2014

...NEW AVIATION DISCUSSION...

.SYNOPSIS...

A SLIGHT CHANCE OF THUNDERSTORMS TODAY IN LOS ANGELES COUNTY AND IN
THE VENTURA COUNTY MOUNTAINS. A SLIGHT CHANCE OF THUNDERSTORMS
TOMORROW IN THE LOS ANGELES AND VENTURA COUNTY MOUNTAINS AND THE
ANTELOPE VALLEY. AFTERNOON HIGHS BELOW NORMAL THROUGH THE END OF THE
WEEK WITH LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS.
CLEARER SKIES AND WARMER TEMPERATURES ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
*** MID-MORNING DISCUSSION UPDATE ***
BIG QUESTION TODAY WILL BE WHETHER AND WHEN THUNDERSTORMS SLIDE INTO
LOS ANGELES COUNTY TODAY AND IF ANY DEVELOPMENT MAKES IT INTO THE
VENTURA COUNTY MOUNTAINS AS WELL.  THE PRIMARY RAIN BAND CONTINUES
TO SLIDE SOUTHEASTWARD ACROSS SAN DIEGO... RIVERSIDE... AND SAN
BERNARDINO COUNTIES THIS MORNING.  HOWEVER AS THE CENTER OF THE LOW
DROPS SOUTHWARD INDICATES CONTINUE TO SHOW A LIKELIHOOD OF THE
THUNDERSTORM BAND WRAPPING AROUND INTO LOS ANGELES COUNTY THIS
AFTERNOON.  WITH GOOD INSTABILITY STRINGING ACROSS THE REGION INTO
THE MOUNTAINS OF SAN LUIS OBISPO COUNTY IT APPEARS THAT DEVELOPMENT
WILL NOT BE A PROBLEM BUT THE BEST MOISTURE APPEARS TO STAY TO THE
SOUTHEAST SO THIS COULD BE A LIMITING FACTOR ESPECIALLY FOR ANYTHING
WEST OF THE SAN GABRIEL RANGE.  LOOKS BETTER TOMORROW... BUT THEN
THE LOW MAY BE OUT OF POSITION.

NOT ANTICIPATING ANY NOTABLE CHANGES TO THE FORECAST PACKAGE AT THIS
TIME OTHER THAN POSSIBLE TWEAKING FOR THUNDERSTORM DEVELOPMENT TODAY
AND TOMORROW.

*** EARLY MORNING DISCUSSION ***
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...20/1800Z.
A COOL DISTURBANCE ALOFT HAS MANAGED TO KEEP A LINE OF THUNDERSTORMS
GOING JUST SOUTH OF OUR FORECAST AREA...BUT SO FAR THERE HAS BEEN NO
EFFECT ON OUR FORECAST DISTRICT. THERE IS A CONTINUED CHANCE OF
THUNDERSTORM ACTIVITY IN THE DESERT TAFS AND IT IS MENTIONED IN THE
KPMD AND KWJF TAFS. OTHERWISE...EXPECTING A RETURN OF THE MARINE
CLOUDS TONIGHT INTO THURSDAY MORNING WITH A MARINE LAYER DEPTH OF
AROUND 3000 FEET SOUTH WITH SOME SHALLOWING POSSIBLE NORTH OF POINT
CONCEPTION AND MVFR TO VFR CEILINGS. THERE IS A SLIGHT CHANCE THAT
THE MARINE CLOUDS WILL NOT DEVELOP AT EXPECTED.

KLAX AND KBUR...GOOD CONFIDENCE IN THE 18Z TAFS. THERE IS A 20
PERCENT CHANCE OF VFR CONDITIONS THROUGH THURSDAY.

&&

.MARINE...20/900 AM...

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE/KJ
AVIATION...SWEET
MARINE...SWEET
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES
















000
FXUS66 KLOX 201617 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
900 AM PDT WED AUG 20 2014

.SYNOPSIS...

A SLIGHT CHANCE OF THUNDERSTORMS TODAY IN LOS ANGELES COUNTY AND IN
THE VENTURA COUNTY MOUNTAINS. A SLIGHT CHANCE OF THUNDERSTORMS
TOMORROW IN THE LOS ANGELES AND VENTURA COUNTY MOUNTAINS AND THE
ANTELOPE VALLEY. AFTERNOON HIGHS BELOW NORMAL THROUGH THE END OF THE
WEEK WITH LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS.
CLEARER SKIES AND WARMER TEMPERATURES ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
*** MID-MORNING DISCUSSION UPDATE ***
BIG QUESTION TODAY WILL BE WHETHER AND WHEN THUNDERSTORMS SLIDE INTO
LOS ANGELES COUNTY TODAY AND IF ANY DEVELOPMENT MAKES IT INTO THE
VENTURA COUNTY MOUNTAINS AS WELL.  THE PRIMARY RAIN BAND CONTINUES
TO SLIDE SOUTHEASTWARD ACROSS SAN DIEGO... RIVERSIDE... AND SAN
BERNARDINO COUNTIES THIS MORNING.  HOWEVER AS THE CENTER OF THE LOW
DROPS SOUTHWARD INDICATES CONTINUE TO SHOW A LIKELIHOOD OF THE
THUNDERSTORM BAND WRAPPING AROUND INTO LOS ANGELES COUNTY THIS
AFTERNOON.  WITH GOOD INSTABILITY STRINGING ACROSS THE REGION INTO
THE MOUNTAINS OF SAN LUIS OBISPO COUNTY IT APPEARS THAT DEVELOPMENT
WILL NOT BE A PROBLEM BUT THE BEST MOISTURE APPEARS TO STAY TO THE
SOUTHEAST SO THIS COULD BE A LIMITING FACTOR ESPECIALLY FOR ANYTHING
WEST OF THE SAN GABRIEL RANGE.  LOOKS BETTER TOMORROW... BUT THEN
THE LOW MAY BE OUT OF POSITION.

NOT ANTICIPATING ANY NOTABLE CHANGES TO THE FORECAST PACKAGE AT THIS
TIME OTHER THAN POSSIBLE TWEAKING FOR THUNDERSTORM DEVELOPMENT TODAY
AND TOMORROW.

*** EARLY MORNING DISCUSSION ***
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...20/1115Z...

LATEST AMDAR SOUNDINGS INDICATE MARINE INVERSION AROUND 3000 FEET
AND SATELLITE/SURFACE OBS INDICATE COASTAL/VALLEY TAF SITES
BLANKETED IN MVFR CIGS. EXPECT MVFR CONDS TO CONTINUE THROUGH EARLY
THIS AFTERNOON...THEN LOW CLOUDS SHOULD CLEAR TO THE COAST. RETURN
TONIGHT SHOULD BE VERY SIMILAR WITH REGARD TO CIG CATEGORY AND
STRATUS COVERAGE. HOWEVER...ANY IMPACTS FROM POSSIBLE CONVECTION
COULD GREATLY CHANGE THE STRATUS PICTURE.

AS FOR THUNDERSTORMS...CURRENTLY ACTIVITY IS SOUTH OF ORANGE COUNTY.
HOWEVER AS THE UPPER LOW WOBBLES...THIS ACTIVITY COULD MOVE INTO LOS
ANGELES COUNTY TODAY. AT THIS TIME...CHANCES FOR ANY THUNDERSTORMS
AT TAF SITES IS LOW...SO ONLY ABOUT A 10% CHANCE THROUGH THIS
EVENING ALTHOUGH WILL CARRY A CB CLOUD GROUP THIS AFTERNOON FOR KPMD
AND KWJF.

KLAX...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. CONFIDENCE IN CLEARING THIS AFTERNOON IS
LOW...AND MAY NOT OCCUR. THERE WILL ALSO BE A 10% CHANCE OF A TSTM
IMPACTING THE AIRFIELD THROUGH THIS EVENING. WILL MONITOR CLOSELY.

KBUR...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING OF
CLEARING THIS AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING
THE AIRFIELD THROUGH THIS EVENING.

&&

.MARINE...20/900 AM...

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE/KJ
AVIATION...RAT
MARINE...SWEET
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES












000
FXUS66 KLOX 201617 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
900 AM PDT WED AUG 20 2014

.SYNOPSIS...

A SLIGHT CHANCE OF THUNDERSTORMS TODAY IN LOS ANGELES COUNTY AND IN
THE VENTURA COUNTY MOUNTAINS. A SLIGHT CHANCE OF THUNDERSTORMS
TOMORROW IN THE LOS ANGELES AND VENTURA COUNTY MOUNTAINS AND THE
ANTELOPE VALLEY. AFTERNOON HIGHS BELOW NORMAL THROUGH THE END OF THE
WEEK WITH LOW CLOUDS ALONG THE COAST AND IN ADJACENT VALLEYS.
CLEARER SKIES AND WARMER TEMPERATURES ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
*** MID-MORNING DISCUSSION UPDATE ***
BIG QUESTION TODAY WILL BE WHETHER AND WHEN THUNDERSTORMS SLIDE INTO
LOS ANGELES COUNTY TODAY AND IF ANY DEVELOPMENT MAKES IT INTO THE
VENTURA COUNTY MOUNTAINS AS WELL.  THE PRIMARY RAIN BAND CONTINUES
TO SLIDE SOUTHEASTWARD ACROSS SAN DIEGO... RIVERSIDE... AND SAN
BERNARDINO COUNTIES THIS MORNING.  HOWEVER AS THE CENTER OF THE LOW
DROPS SOUTHWARD INDICATES CONTINUE TO SHOW A LIKELIHOOD OF THE
THUNDERSTORM BAND WRAPPING AROUND INTO LOS ANGELES COUNTY THIS
AFTERNOON.  WITH GOOD INSTABILITY STRINGING ACROSS THE REGION INTO
THE MOUNTAINS OF SAN LUIS OBISPO COUNTY IT APPEARS THAT DEVELOPMENT
WILL NOT BE A PROBLEM BUT THE BEST MOISTURE APPEARS TO STAY TO THE
SOUTHEAST SO THIS COULD BE A LIMITING FACTOR ESPECIALLY FOR ANYTHING
WEST OF THE SAN GABRIEL RANGE.  LOOKS BETTER TOMORROW... BUT THEN
THE LOW MAY BE OUT OF POSITION.

NOT ANTICIPATING ANY NOTABLE CHANGES TO THE FORECAST PACKAGE AT THIS
TIME OTHER THAN POSSIBLE TWEAKING FOR THUNDERSTORM DEVELOPMENT TODAY
AND TOMORROW.

*** EARLY MORNING DISCUSSION ***
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...20/1115Z...

LATEST AMDAR SOUNDINGS INDICATE MARINE INVERSION AROUND 3000 FEET
AND SATELLITE/SURFACE OBS INDICATE COASTAL/VALLEY TAF SITES
BLANKETED IN MVFR CIGS. EXPECT MVFR CONDS TO CONTINUE THROUGH EARLY
THIS AFTERNOON...THEN LOW CLOUDS SHOULD CLEAR TO THE COAST. RETURN
TONIGHT SHOULD BE VERY SIMILAR WITH REGARD TO CIG CATEGORY AND
STRATUS COVERAGE. HOWEVER...ANY IMPACTS FROM POSSIBLE CONVECTION
COULD GREATLY CHANGE THE STRATUS PICTURE.

AS FOR THUNDERSTORMS...CURRENTLY ACTIVITY IS SOUTH OF ORANGE COUNTY.
HOWEVER AS THE UPPER LOW WOBBLES...THIS ACTIVITY COULD MOVE INTO LOS
ANGELES COUNTY TODAY. AT THIS TIME...CHANCES FOR ANY THUNDERSTORMS
AT TAF SITES IS LOW...SO ONLY ABOUT A 10% CHANCE THROUGH THIS
EVENING ALTHOUGH WILL CARRY A CB CLOUD GROUP THIS AFTERNOON FOR KPMD
AND KWJF.

KLAX...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. CONFIDENCE IN CLEARING THIS AFTERNOON IS
LOW...AND MAY NOT OCCUR. THERE WILL ALSO BE A 10% CHANCE OF A TSTM
IMPACTING THE AIRFIELD THROUGH THIS EVENING. WILL MONITOR CLOSELY.

KBUR...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING OF
CLEARING THIS AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING
THE AIRFIELD THROUGH THIS EVENING.

&&

.MARINE...20/900 AM...

NO SIGNIFICANT WIND ISSUES ANTICIPATED ACROSS THE COASTAL WATERS FOR
THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE/KJ
AVIATION...RAT
MARINE...SWEET
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES













000
FXUS66 KLOX 201116 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
415 AM PDT WED AUG 20 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

AN UPPER LOW WILL DRIFT ACROSS THE REGION TODAY THROUGH FRIDAY. IT
WILL BRING LOW CLOUDS TO THE COASTS AND VALLEYS. IT WILL ALSO BRING
A CHANCE OF THUNDERSTORMS TO L.A. COUNTY TODAY AND A SLIGHT CHANCE
OF THUNDERSTORMS TO THE L.A. AND VENTURA MOUNTAINS AS WELL AS THE
ANTELOPE VALLEY THURSDAY. AFTERNOON HIGHS WILL BE BELOW NORMAL
THROUGH THE END OF THE WEEK. CLEARER SKIES AND WARMER TEMPERATURES
ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...20/1115Z...

LATEST AMDAR SOUNDINGS INDICATE MARINE INVERSION AROUND 3000 FEET
AND SATELLITE/SURFACE OBS INDICATE COASTAL/VALLEY TAF SITES
BLANKETED IN MVFR CIGS. EXPECT MVFR CONDS TO CONTINUE THROUGH EARLY
THIS AFTERNOON...THEN LOW CLOUDS SHOULD CLEAR TO THE COAST. RETURN
TONIGHT SHOULD BE VERY SIMILAR WITH REGARD TO CIG CATEGORY AND
STRATUS COVERAGE. HOWEVER...ANY IMPACTS FROM POSSIBLE CONVECTION
COULD GREATLY CHANGE THE STRATUS PICTURE.

AS FOR THUNDERSTORMS...CURRENTLY ACTIVITY IS SOUTH OF ORANGE COUNTY.
HOWEVER AS THE UPPER LOW WOBBLES...THIS ACTIVITY COULD MOVE INTO LOS
ANGELES COUNTY TODAY. AT THIS TIME...CHANCES FOR ANY THUNDERSTORMS
AT TAF SITES IS LOW...SO ONLY ABOUT A 10% CHANCE THROUGH THIS
EVENING ALTHOUGH WILL CARRY A CB CLOUD GROUP THIS AFTERNOON FOR KPMD
AND KWJF.

KLAX...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. CONFIDENCE IN CLEARING THIS AFTERNOON IS
LOW...AND MAY NOT OCCUR. THERE WILL ALSO BE A 10% CHANCE OF A TSTM
IMPACTING THE AIRFIELD THROUGH THIS EVENING. WILL MONITOR CLOSELY.

KBUR...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING OF
CLEARING THIS AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING
THE AIRFIELD THROUGH THIS EVENING.

&&

.MARINE...

20/200 AM

NO SIGNIFICANT WIND ISSUES ANTICIPATED WIND ISSUES ANTICIPATED
ACROSS THE COASTAL WATERS FOR THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...RAT
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES









000
FXUS66 KLOX 201116 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
415 AM PDT WED AUG 20 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

AN UPPER LOW WILL DRIFT ACROSS THE REGION TODAY THROUGH FRIDAY. IT
WILL BRING LOW CLOUDS TO THE COASTS AND VALLEYS. IT WILL ALSO BRING
A CHANCE OF THUNDERSTORMS TO L.A. COUNTY TODAY AND A SLIGHT CHANCE
OF THUNDERSTORMS TO THE L.A. AND VENTURA MOUNTAINS AS WELL AS THE
ANTELOPE VALLEY THURSDAY. AFTERNOON HIGHS WILL BE BELOW NORMAL
THROUGH THE END OF THE WEEK. CLEARER SKIES AND WARMER TEMPERATURES
ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...20/1115Z...

LATEST AMDAR SOUNDINGS INDICATE MARINE INVERSION AROUND 3000 FEET
AND SATELLITE/SURFACE OBS INDICATE COASTAL/VALLEY TAF SITES
BLANKETED IN MVFR CIGS. EXPECT MVFR CONDS TO CONTINUE THROUGH EARLY
THIS AFTERNOON...THEN LOW CLOUDS SHOULD CLEAR TO THE COAST. RETURN
TONIGHT SHOULD BE VERY SIMILAR WITH REGARD TO CIG CATEGORY AND
STRATUS COVERAGE. HOWEVER...ANY IMPACTS FROM POSSIBLE CONVECTION
COULD GREATLY CHANGE THE STRATUS PICTURE.

AS FOR THUNDERSTORMS...CURRENTLY ACTIVITY IS SOUTH OF ORANGE COUNTY.
HOWEVER AS THE UPPER LOW WOBBLES...THIS ACTIVITY COULD MOVE INTO LOS
ANGELES COUNTY TODAY. AT THIS TIME...CHANCES FOR ANY THUNDERSTORMS
AT TAF SITES IS LOW...SO ONLY ABOUT A 10% CHANCE THROUGH THIS
EVENING ALTHOUGH WILL CARRY A CB CLOUD GROUP THIS AFTERNOON FOR KPMD
AND KWJF.

KLAX...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. CONFIDENCE IN CLEARING THIS AFTERNOON IS
LOW...AND MAY NOT OCCUR. THERE WILL ALSO BE A 10% CHANCE OF A TSTM
IMPACTING THE AIRFIELD THROUGH THIS EVENING. WILL MONITOR CLOSELY.

KBUR...MODERATE CONFIDENCE IN 12Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH THIS MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING OF
CLEARING THIS AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING
THE AIRFIELD THROUGH THIS EVENING.

&&

.MARINE...

20/200 AM

NO SIGNIFICANT WIND ISSUES ANTICIPATED WIND ISSUES ANTICIPATED
ACROSS THE COASTAL WATERS FOR THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...RAT
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES










000
FXUS66 KLOX 201046
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
340 AM PDT WED AUG 20 2014

.SYNOPSIS...

AN UPPER LOW WILL DRIFT ACROSS THE REGION TODAY THROUGH FRIDAY. IT
WILL BRING LOW CLOUDS TO THE COASTS AND VALLEYS. IT WILL ALSO BRING
A CHANCE OF THUNDERSTORMS TO L.A. COUNTY TODAY AND A SLIGHT CHANCE
OF THUNDERSTORMS TO THE L.A. AND VENTURA MOUNTAINS AS WELL AS THE
ANTELOPE VALLEY THURSDAY. AFTERNOON HIGHS WILL BE BELOW NORMAL
THROUGH THE END OF THE WEEK. CLEARER SKIES AND WARMER TEMPERATURES
ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...

20/0515Z

OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. WITH UPPER LOW
WOBBLING NEAR THE AREA...MARINE INVERSION SHOULD DEEPEN AND MVFR
CIGS SHOULD IMPACT ALL COASTAL/VALLEY TAF SITES OVERNIGHT. COULD BE
SLOW TO CLEAR WEDNESDAY AFTERNOON SOUTH OF POINT CONCEPTION...BUT
THE PREVIOUSLY MENTIONED UPPER LOW COULD MIX OUT THE MVFR CIGS
EARLIER/BETTER THAN ANTICIPATED. WITH THE DEEPENING INVERSION...THERE
COULD BE SOME PATCHY DRIZZLE WEST OF THE MOUNTAINS OVERNIGHT.

OTHER ISSUE TO WATCH WILL BE SLIGHT CHANCE OF TSTMS IMPACTING MAINLY
LOS ANGELES COUNTY LATE TONIGHT AND WEDNESDAY. AT THIS TIME...WILL
MENTION A VCTS REMARK WEDNESDAY AFTERNOON FOR KPMD/KWJF. HOWEVER
DEPENDING ON HOW THINGS DEVELOP LATE TONIGHT...THERE IS THE
POTENTIAL FOR TSTMS TO IMPACT KLAX/KLGB/KBUR/KVNY. WILL WATCH THE
SITUATION CLOSELY.

KLAX...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING...WITH LOW CONFIDENCE IN CLEARING
WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE
AIRFIELD LATE TONIGHT/WEDNESDAY.

KBUR...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING
OF CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS
IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY.

&&

.MARINE...

20/200 AM

NO SIGNIFICANT WIND ISSUES ANTICIPATED WIND ISSUES ANTICIPATED
ACROSS THE COASTAL WATERS FOR THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...RAT
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES







000
FXUS66 KLOX 201046
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
340 AM PDT WED AUG 20 2014

.SYNOPSIS...

AN UPPER LOW WILL DRIFT ACROSS THE REGION TODAY THROUGH FRIDAY. IT
WILL BRING LOW CLOUDS TO THE COASTS AND VALLEYS. IT WILL ALSO BRING
A CHANCE OF THUNDERSTORMS TO L.A. COUNTY TODAY AND A SLIGHT CHANCE
OF THUNDERSTORMS TO THE L.A. AND VENTURA MOUNTAINS AS WELL AS THE
ANTELOPE VALLEY THURSDAY. AFTERNOON HIGHS WILL BE BELOW NORMAL
THROUGH THE END OF THE WEEK. CLEARER SKIES AND WARMER TEMPERATURES
ARE ON TAP FOR THE WEEKEND.

&&

.SHORT TERM (TODAY-FRI)...
WHAT A DIFFERENCE 60 MILES MAKES. ALL OF L.A. COUNTIES COASTS AND
VLYS AS WELL AS THE COASTAL SLOPES ARE COVERED WITH LOW CLOUDS. 60
MILES SOUTH AT THE NW TIP OF SAN DIEGO COUNTY A PERSISTENT LINE OF
TSTMS IS RUMBLING ON. THE MARINE LAYER IS 3000 FEET DEEP BUT THE
CLOUD LAYER IS PRETTY THIN AND EXPECT DECENT CLEARING TODAY...EXCEPT
FOR THE CENTRAL COAST WHERE THE BEACHES WILL SEE SLOW TO NO
CLEARING. THE COASTAL/VALLEY FORECAST SAYS MOSTLY SUNNY THIS
AFTERNOON BUT THIS DEEP A MARINE LAYER MIGHT PRODUCE SOME AFTERNOON
STRATA CU. TSTMS ARE THE REAL STORY OF THE DAY. ALL BROUGHT TO US
COURTESY OF 576 DM UP LOW JUST TO THE WEST OF CATALINA ISLAND. A
VORT MAX WHIPPING AROUND THE BASE OF THE LOW IS PROVIDING THE FOCUS
FOR THE SAN DIEGO COUNTY TSTMS. THERE IS A SLIGHT CHC THAT A TSTM
COULD FORM OVER L.A. COUNTY OR THE ADJACENT WATERS EARLY THIS
MORNING BUT FOR THE MOST PART THE CONVECTION WILL STAY TO THE SOUTH.
THINGS CHANGE LATER THIS MORNING HOWEVER. THE UPPER LOW DROP A
LITTLE MORE SOUTHWARD AND THE FLOW PATTERN SHIFTS FROM THE SW TO THE
SSW. THIS WILL PUSH THE MOISTURE AND LIFT FORM THE UPPER LOW
NORTHWARD INTO ERN LA COUNTY. BY EARLY AFTERNOON THE LOW HAS SETTLED
FURTHER SOUTH AND THE FLOW PATTERN GOES FROM NEAR SAN CLEMENTE TO
PASADENA TO LANCASTER. THIS FLOW PATTERN LOOKS PRETTY CONDUCIVE FOR
CONVECTION AND SHOULD LAST INTO THE EVENING. THE LA COASTS AND VLY
WILL HAVE A SLIGHT CHC OF TSTMS WHILE THE MTNS AND DESERTS (AS WELL
AS THE VTA COUNTY MTNS) WILL HAVE A CHC. THERE IS NOT MUCH MOISTURE
TO WORK WITH AND ANY STORMS THAT DO FORM WILL MOVE AT A PRETTY GOOD
CLIP SO THE THREAT OF FLASH FLOODING IS FAIRLY SMALL. 578 HGTS...
THE DEEP MARINE LAYER AND GOOD ONSHORE FLOW WILL ALL CONTRIBUTE TO A
MUCH COOLER THAN NORMAL DAY.

UNLESS SOME REALLY HUGE TSTMS DEVELOP TODAY WITH OUTFLOW POWERFUL
ENOUGH TO DISRUPT THE MARINE INVERSION (UNLIKELY) THERE WILL BE
ANOTHER ROUND OF LOW CLOUDS COVERING THE COASTS AND VLYS TONIGHT.
EXPECT GOOD CLEARING THURSDAY AND ALMOST ALL AREAS SHOULD BE SUNNY
BY NOON. THERE IS JUST ENOUGH WRAP AROUND MOISTURE ASSOC WITH THE
EXITING UPPER LOW TO ALLOW FOR A SLIGHT CHC OF AFTERNOON TSTMS OVER
THE LA/VTA MTNS. MAX TEMPS WILL RISE SOME DUE TO HIGHER HGTS AND
WEAKER ONSHORE FLOW BUT ALL TEMPS WILL STILL BE BLO NORMAL.

THE UPPER LOW WILL OPEN UP AND MOVE EASTWARD INTO ARIZONA BY
THURSDAY NIGHT AND WILL NO LONGER INFLUENCE OUR WEATHER. HGTS RISE
AND THE ONSHORE FLOW DECREASES THE MARINE LAYER WILL SHRINK. IT WILL
MOST LIKELY SHRINK OUT OF THE VLYS BUT THERE IS A 30 OR 40 PERCENT
CHANCE THAT SOME VLYS WILL HAVE ONE MORE NIGHT OF LOW CLOUDS. MORE
WARMING WILL BRING MAX TEMPS BACK CLOSE TO NORMAL.

.LONG TERM (SAT-TUE)...
EXTENDED MDLS HAVE BEEN TERRIBLE ALL SUMMER AND TONIGHTS RUN ARE
EQUALLY TROUBLED. YESTERDAYS BUILDING HIGH PRESSURE WAS DIFFERENT
FROM MONDAYS CULL AREA FCST AND TODAYS FORECAST CALLS FOR 4 DAYS OF
A LONG WAVE TROF. DID NOT MAKE A BUNCH OF CHANGED TO THE LONG RANGE
FORECAST. LOWERED MAX TEMPS A FEW DEGREES SINCE THE THE RIDGE IS NO
LONGER IN THE PICTURE...BUT DID NOT MESS WITH THE MARINE LAYER
CLOUDS WHICH IF THIS SCENARIO COMES TRUE WILL BE DEEPER THAN FCST
AND WILL AFFECT THE VLYS.

&&

.AVIATION...

20/0515Z

OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. WITH UPPER LOW
WOBBLING NEAR THE AREA...MARINE INVERSION SHOULD DEEPEN AND MVFR
CIGS SHOULD IMPACT ALL COASTAL/VALLEY TAF SITES OVERNIGHT. COULD BE
SLOW TO CLEAR WEDNESDAY AFTERNOON SOUTH OF POINT CONCEPTION...BUT
THE PREVIOUSLY MENTIONED UPPER LOW COULD MIX OUT THE MVFR CIGS
EARLIER/BETTER THAN ANTICIPATED. WITH THE DEEPENING INVERSION...THERE
COULD BE SOME PATCHY DRIZZLE WEST OF THE MOUNTAINS OVERNIGHT.

OTHER ISSUE TO WATCH WILL BE SLIGHT CHANCE OF TSTMS IMPACTING MAINLY
LOS ANGELES COUNTY LATE TONIGHT AND WEDNESDAY. AT THIS TIME...WILL
MENTION A VCTS REMARK WEDNESDAY AFTERNOON FOR KPMD/KWJF. HOWEVER
DEPENDING ON HOW THINGS DEVELOP LATE TONIGHT...THERE IS THE
POTENTIAL FOR TSTMS TO IMPACT KLAX/KLGB/KBUR/KVNY. WILL WATCH THE
SITUATION CLOSELY.

KLAX...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING...WITH LOW CONFIDENCE IN CLEARING
WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE
AIRFIELD LATE TONIGHT/WEDNESDAY.

KBUR...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING
OF CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS
IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY.

&&

.MARINE...

20/200 AM

NO SIGNIFICANT WIND ISSUES ANTICIPATED WIND ISSUES ANTICIPATED
ACROSS THE COASTAL WATERS FOR THE NEXT SEVERAL DAYS.

THERE IS THE POSSIBILITY OF SOME ISOLATED THUNDERSTORMS ACROSS THE
SOUTHERN WATERS THROUGH THIS EVENING...WITH GUSTY WINDS AND CHOPPY
SEAS LIKELY WITH ANY THUNDERSTORMS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...RAT
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES






000
FXUS66 KLOX 200515 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1015 PM PDT TUE AUG 19 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE
THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE
MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF
SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A
HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK
WITH ABOVE NORMAL TEMPERATURES.

&&

.UPDATE...

THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM
CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS
EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF
THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER
SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO
THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST
FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF
STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE
STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH
APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE.

THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE
CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT.
BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN
AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN
COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE
TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT
SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD
ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE
MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL
WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT.

THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING
LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM-
WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR
THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM-
WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE
FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS
WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND
SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER
MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE
TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO
FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER
POSSIBILITIES FOR THURSDAY.

&&

.PREV DISCUSSION...

SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS
ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER
THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF
THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY
MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY
VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER
SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT
CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK
BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW
ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND.

LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER
THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER
BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE
SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM
TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED
NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY
EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST
WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...20/0515Z...

OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. WITH UPPER LOW
WOBBLING NEAR THE AREA...MARINE INVERSION SHOULD DEEPEN AND MVFR
CIGS SHOULD IMPACT ALL COASTAL/VALLEY TAF SITES OVERNIGHT. COULD BE
SLOW TO CLEAR WEDNESDAY AFTERNOON SOUTH OF POINT CONCEPTION...BUT
THE PREVIOUSLY MENTIONED UPPER LOW COULD MIX OUT THE MVFR CIGS
EARLIER/BETTER THAN ANTICIPATED. WITH THE DEEPENING INVERSION...THERE
COULD BE SOME PATCHY DRIZZLE WEST OF THE MOUNTAINS OVERNIGHT.

OTHER ISSUE TO WATCH WILL BE SLIGHT CHANCE OF TSTMS IMPACTING MAINLY
LOS ANGELES COUNTY LATE TONIGHT AND WEDNESDAY. AT THIS TIME...WILL
MENTION A VCTS REMARK WEDNESDAY AFTERNOON FOR KPMD/KWJF. HOWEVER
DEPENDING ON HOW THINGS DEVELOP LATE TONIGHT...THERE IS THE
POTENTIAL FOR TSTMS TO IMPACT KLAX/KLGB/KBUR/KVNY. WILL WATCH THE
SITUATION CLOSELY.

KLAX...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING...WITH LOW CONFIDENCE IN CLEARING
WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE
AIRFIELD LATE TONIGHT/WEDNESDAY.

KBUR...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING
OF CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS
IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY.

&&

.MARINE...19/900 PM.

TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED
TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP
ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND
ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO-
OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH
WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWWLOX).

&&

$$

PUBLIC...HALL/BOLDT
AVIATION...GOMBERG
MARINE...HALL
SYNOPSIS...SETO/HALL

WWW.WEATHER.GOV/LOSANGELES








000
FXUS66 KLOX 200515 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1015 PM PDT TUE AUG 19 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE
THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE
MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF
SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A
HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK
WITH ABOVE NORMAL TEMPERATURES.

&&

.UPDATE...

THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM
CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS
EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF
THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER
SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO
THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST
FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF
STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE
STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH
APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE.

THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE
CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT.
BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN
AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN
COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE
TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT
SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD
ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE
MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL
WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT.

THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING
LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM-
WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR
THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM-
WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE
FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS
WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND
SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER
MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE
TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO
FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER
POSSIBILITIES FOR THURSDAY.

&&

.PREV DISCUSSION...

SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS
ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER
THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF
THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY
MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY
VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER
SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT
CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK
BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW
ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND.

LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER
THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER
BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE
SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM
TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED
NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY
EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST
WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...20/0515Z...

OVERALL...MODERATE CONFIDENCE IN 06Z TAF PACKAGE. WITH UPPER LOW
WOBBLING NEAR THE AREA...MARINE INVERSION SHOULD DEEPEN AND MVFR
CIGS SHOULD IMPACT ALL COASTAL/VALLEY TAF SITES OVERNIGHT. COULD BE
SLOW TO CLEAR WEDNESDAY AFTERNOON SOUTH OF POINT CONCEPTION...BUT
THE PREVIOUSLY MENTIONED UPPER LOW COULD MIX OUT THE MVFR CIGS
EARLIER/BETTER THAN ANTICIPATED. WITH THE DEEPENING INVERSION...THERE
COULD BE SOME PATCHY DRIZZLE WEST OF THE MOUNTAINS OVERNIGHT.

OTHER ISSUE TO WATCH WILL BE SLIGHT CHANCE OF TSTMS IMPACTING MAINLY
LOS ANGELES COUNTY LATE TONIGHT AND WEDNESDAY. AT THIS TIME...WILL
MENTION A VCTS REMARK WEDNESDAY AFTERNOON FOR KPMD/KWJF. HOWEVER
DEPENDING ON HOW THINGS DEVELOP LATE TONIGHT...THERE IS THE
POTENTIAL FOR TSTMS TO IMPACT KLAX/KLGB/KBUR/KVNY. WILL WATCH THE
SITUATION CLOSELY.

KLAX...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING...WITH LOW CONFIDENCE IN CLEARING
WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS IMPACTING THE
AIRFIELD LATE TONIGHT/WEDNESDAY.

KBUR...MODERATE CONFIDENCE IN 06Z TAF. HIGH CONFIDENCE IN MVFR CIGS
THROUGH WEDNESDAY MORNING. LOW CONFIDENCE IN CURRENT FORECAST/TIMING
OF CLEARING WEDNESDAY AFTERNOON. THERE IS A 10% CHANCE OF TSTMS
IMPACTING THE AIRFIELD LATE TONIGHT/WEDNESDAY.

&&

.MARINE...19/900 PM.

TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED
TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP
ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND
ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO-
OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH
WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWWLOX).

&&

$$

PUBLIC...HALL/BOLDT
AVIATION...GOMBERG
MARINE...HALL
SYNOPSIS...SETO/HALL

WWW.WEATHER.GOV/LOSANGELES









000
FXUS66 KLOX 200358
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
858 PM PDT TUE AUG 19 2014

.SYNOPSIS...

A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE
THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE
MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF
SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A
HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK
WITH ABOVE NORMAL TEMPERATURES.

&&

.UPDATE...

THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM
CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS
EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF
THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER
SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO
THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST
FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF
STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE
STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH
APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE.

THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE
CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT.
BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN
AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN
COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE
TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT
SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD
ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE
MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL
WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT.

THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING
LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM-
WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR
THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM-
WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE
FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS
WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND
SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER
MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE
TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO
FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER
POSSIBILITIES FOR THURSDAY.

&&

.PREV DISCUSSION...

SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS
ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER
THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF
THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY
MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY
VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER
SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT
CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK
BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW
ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND.

LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER
THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER
BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE
SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM
TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED
NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY
EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST
WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...19/2320Z.

UPPER LOW NEAR POINT CONCEPTION WILL CONTINUE TO MAINTAIN A DEEP MARINE
LAYER THROUGH PERIOD...RISING TO AROUND 4000 FEET ACROSS AREAS SOUTH OF
POINT CONCEPTION BY WEDNESDAY MORNING. EXPECTING MVFR CIGS TO BE
MORE WIDESPREAD ACROSS COASTAL/VALLEY TAF LOCATIONS TONIGHT...WITH LOWEST
CONFIDENCE IN TIMING ACROSS LA COUNTY. THERE IS A CHANCE OF DRIZZLE
OVERNIGHT ACROSS COASTAL/VALLEY LOCATIONS. THEN ON WEDNESDAY...THERE
WILL BE A 20 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL OF
LA COUNTY AS WELL AS THE VENTURA COUNTY MOUNTAINS.

KLAX AND KBUR...POOR CONFIDENCE IN ARRIVAL TIME OF MVFR CIGS
TONIGHT. IF LOW CLOUDS DEVELOP...THERE WILL BE A CHANCE OF DRIZZLE
OVERNIGHT. AS LOW DRAWS CLOSER...THERE WILL BE A 20 PERCENT CHANCE
OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY.

&&

.MARINE...19/900 PM.

TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED
TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP
ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND
ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO-
OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH
WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWWLOX).

&&

$$

PUBLIC...HALL/BOLDT
AVIATION...GOMBERG
MARINE...HALL
SYNOPSIS...SETO/HALL

WWW.WEATHER.GOV/LOSANGELES






000
FXUS66 KLOX 200358
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
858 PM PDT TUE AUG 19 2014

.SYNOPSIS...

A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION AND INCREASE
THE NIGHT THROUGH MORNING CLOUDS AND FOG THROUGH SATURDAY. THE
MOIST AIR MASS WILL BRING LOCAL DRIZZLE...AND A SLIGHT CHANCE OF
SHOWERS OR THUNDERSTORMS TO THE SOUTHLAND THROUGH THURSDAY. A
HIGH PRESSURE SYSTEM WILL LIKELY ESTABLISH FOR EARLY NEXT WEEK
WITH ABOVE NORMAL TEMPERATURES.

&&

.UPDATE...

THE WATER VAPOR IMAGERY INDICATES A LOW PRESSURE SYSTEM
CONTINUING TO DIG SOUTH OFF THE SOUTHERN CALIFORNIA COAST THIS
EVENING. SOME CONVECTION HAS FIRED OFF TO THE SOUTH AND EAST OF
THE AREA...BUT THE AREA HAS REMAINED DRY. A DEEP MARINE LAYER
SHOULD BRING AN EXTENSIVE MARINE LAYER INDUCED STRATUS FIELD TO
THE MUCH OF THE COASTAL AND VALLEY AREAS LATER TONIGHT. THE LATEST
FOG PRODUCT IS GIVING INDICATIONS OF A RAPID FILLING-IN OF
STRATUS LATE THIS EVENING. DRIZZLE OR LIGHT SHOWERS FROM THE
STRATUS DECK CANNOT BE RULED AS THE INSTABILITY OF THE TROUGH
APPROACHES AND RAPID DEEPENING OF THE MARINE LAYER TAKES PLACE.

THE LATEST NAM-WRF AND RAP SOLUTIONS SUGGEST THE TIMING OF THE
CONVECTION OCCURRING A LITTLE EARLIER THAN PREVIOUSLY THOUGHT.
BOTH 00Z NAM-WRF SOLUTIONS AND THE LATEST RAP SOLUTIONS SUGGEST AN
AREA OF NEGATIVE LIFTED INDEX VALUES FORMING OVER THE SOUTHERN
COASTAL WATERS LATE TONIGHT WHEN THE COLDEST AIR ALOFT WITH THE
TROUGH MOVES INTO THE REGION. AN AREA OF DIFLUENCE FLOW ALOFT
SHOULD DEVELOP AHEAD OF THE MAIN VORTICITY MAXIMUM AND SHOULD
ALLOW FOR SHOWERS AND THUNDERSTORMS TO FIRE...EVEN ABOVE THE
MARINE LAYER STRATUS DECK. POPS HAVE BEEN BUMPED FOR THE COASTAL
WATERS AND THE LOS ANGELES COUNTY COAST AFTER MIDNIGHT TONIGHT.

THE LATEST NAM-WRF SOLUTIONS CONTINUE TO SLOW THE TROUGH...BEING
LESS PROGRESSIVE RELATIVE TO THE GFS AND ECMWF SOLUTIONS. IF NAM-
WRF SOLUTIONS PLAY OUT...POPS AND WEATHER MAY NEED TO BE ADDED FOR
THURSDAY AS THE TROUGH AXIS LINGERS OVER THE AREA. WHILE THE NAM-
WRF SOLUTIONS REMAIN THE OUTLIER...THE TROUGH IS CUT-OFF FROM THE
FLOW AND TYPICALLY MODEL PERFORMANCE WITH CLOSED AND CUT-OFF LOWS
WOULD FAVOR NAM-WRF SOLUTIONS FOR SOUTHERN CALIFORNIA AND
SOUTHWESTERN UNITED STATES. WITH THE NWS WEATHER PREDICTION CENTER
MENTIONING SREF SOLUTIONS FAVORING RETROGRESSION OF THE
TROUGH...IT IS POSSIBLE THAT THE NAM-WRF SOLUTION MAY NOT BE TOO
FAR OFF. THE NEXT SHIFT WILL BE BRIEFED ABOUT POPS AND WEATHER
POSSIBILITIES FOR THURSDAY.

&&

.PREV DISCUSSION...

SHORT TERM...THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS
ON THURSDAY. THE LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER
THE EASTERN SAN GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF
THUNDERSTORMS. A SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY
MORNING BUT WILL STILL SEE LOW CLOUDS FOR COASTS AND NEARBY
VALLEYS TO START THE DAY. BY FRIDAY MORNING THE MARINE LAYER
SHRINKS EVEN MORE AND MAY ONLY SEE PATCHY CLOUDS SOUTH OF PT
CONCEPTION. TEMPERATURES WILL START TO REBOUND LATE IN THE WEEK
BUT A LARGE SCALE UPPER TROUGH ACROSS MOST OF THE WEST WILL SLOW
ANY SIGNIFICANT WARMING UNTIL LATER IN THE WEEKEND.

LONG TERM...HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER
THE WEEKEND WITH TEMPERATURES WARMING AND THE MARINE LAYER
BECOMING LESS OF AN ISSUE FOR COASTAL AREAS. VERY LITTLE
SIGNIFICANT WEATHER ISSUES THROUGH TUESDAY. REMNANT MOISTURE FROM
TWO TROPICAL SYSTEMS (LOWELL AND KARINA) COULD GET PULLED
NORTHWARD CLOSER TO SOUTHERN CALI BY MONDAY OR TUESDAY. WOULD ONLY
EXPECT SOME MID TO HIGH LEVEL CLOUDS FROM THESE SYSTEMS AT BEST
WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...19/2320Z.

UPPER LOW NEAR POINT CONCEPTION WILL CONTINUE TO MAINTAIN A DEEP MARINE
LAYER THROUGH PERIOD...RISING TO AROUND 4000 FEET ACROSS AREAS SOUTH OF
POINT CONCEPTION BY WEDNESDAY MORNING. EXPECTING MVFR CIGS TO BE
MORE WIDESPREAD ACROSS COASTAL/VALLEY TAF LOCATIONS TONIGHT...WITH LOWEST
CONFIDENCE IN TIMING ACROSS LA COUNTY. THERE IS A CHANCE OF DRIZZLE
OVERNIGHT ACROSS COASTAL/VALLEY LOCATIONS. THEN ON WEDNESDAY...THERE
WILL BE A 20 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL OF
LA COUNTY AS WELL AS THE VENTURA COUNTY MOUNTAINS.

KLAX AND KBUR...POOR CONFIDENCE IN ARRIVAL TIME OF MVFR CIGS
TONIGHT. IF LOW CLOUDS DEVELOP...THERE WILL BE A CHANCE OF DRIZZLE
OVERNIGHT. AS LOW DRAWS CLOSER...THERE WILL BE A 20 PERCENT CHANCE
OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY.

&&

.MARINE...19/900 PM.

TIMING FOR CHANCES FOR SHOWERS AND THUNDERSTORMS HAS BEEN BUMPED
TO AN EARLIER TIME FRAME. SHOWERS AND THUNDERSTORMS COULD DEVELOP
ACROSS THE SOUTHERN WATERS AFTER MIDNIGHT TONIGHT. GUSTY AND
ERRATIC WINDS...CHOPPY SEAS...SMALL HAIL...AND DANGEROUS CLOUD-TO-
OCEAN LIGHTNING ARE POSSIBLE AFTER MIDNIGHT TONIGHT AND THROUGH
WEDNESDAY MORNING. OTHERWISE...WINDS AND SEAS WILL REMAIN BELOW
SMALL CRAFT ADVISORY LEVELS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWWLOX).

&&

$$

PUBLIC...HALL/BOLDT
AVIATION...GOMBERG
MARINE...HALL
SYNOPSIS...SETO/HALL

WWW.WEATHER.GOV/LOSANGELES





000
FXUS66 KLOX 192323
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
425 PM PDT TUE AUG 19 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.SHORT TERM (TONIGHT-FRI)...
FORECAST CONCERNS IN THIS PACKAGE...MARINE LAYER/CLOUDS AND SLIGHT
CHANCE OF CONVECTION THROUGH THURSDAY AFTERNOON.

UPPER LOW CONTINUES TO DROP SOUTHWARD ALONG THE CENTRAL COAST THIS
AFTERNOON AND WILL BE OVER THE CHANNEL ISLANDS WEDNESDAY
MORNING...THEN SHIFT TO THE HIGHER DESERTS ON THURSDAY. THIS IS A
RATHER STRONG LOW PRESSURE AREA FOR THIS TIME OF THE YEAR AND SOME
COOL AIR ALOFT IS ASSOCIATED WITH IT. THE MAIN PROBLEM WITH THIS
SYSTEM IS A LACK OF ADEQUATE MOISTURE ACROSS SOUTHWEST CALI AND NOT
MUCH OF A FETCH TO ADVECT MOISTURE FROM THE OCEAN. HOWEVER...UPPER
LOWS ARE NOTORIOUS FOR GENERATING PRECIPITATION OUT OF RATHER POOR
ATMOSPHERIC MOISTURE CONTENT.

INSTABILITY WITH THIS SYSTEM IS NOT LACKING...8 DEGREE C LAPSE RATES
BETWEEN 700-500MB...NEGATIVE LIFTED INDEX...SURFACE CAPE...AND
CYCLONIC FLOW WITH DIVERGENCE ALOFT. OTHER ISSUE IS MARINE LAYER
WILL REMAIN VERY THICK OVER 3K FEET. WRF CONTINUES TO SHOW
INCREASING INSTABILITY OVER THE SOUTH COASTAL WATERS AND LA BASIN
WEDNESDAY MORNING. COULD SEE LIGHTNING AT SAME TIME OF LOW CLOUD
COVER DURING MORNING COMMUTE. BEST MOISTURE PLUME SWINGS ACROSS SAN
DIEGO COUNTY AND NOSES BACK INTO THE LA COUNTY MOUNTAINS WEDNESDAY
AFTERNOON. THIS WILL BE OUR BEST FOCUS FOR THUNDERSTORMS TOMORROW
WITH MAINLY LINGERING LIGHT SHOWERS ACROSS THE COAST AND VALLEYS OF
LOS ANGELES COUNTY. TEMPERATURES WILL REMAIN STUNTED BELOW NORMAL ON
WEDNESDAY...RUNNING A GOOD 10-20 DEGREES COOLER TODAY COMPARED TO
YESTERDAY.

THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS ON THURSDAY. THE
LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER THE EASTERN SAN
GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF THUNDERSTORMS. A
SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY MORNING BUT WILL STILL
SEE LOW CLOUDS FOR COASTS AND NEARBY VALLEYS TO START THE DAY. BY
FRIDAY MORNING THE MARINE LAYER SHRINKS EVEN MORE AND MAY ONLY SEE
PATCHY CLOUDS SOUTH OF PT CONCEPTION. TEMPERATURES WILL START TO
REBOUND LATE IN THE WEEK BUT A LARGE SCALE UPPER TROUGH ACROSS MOST
OF THE WEST WILL SLOW ANY SIGNIFICANT WARMING UNTIL LATER IN THE
WEEKEND.

.LONG TERM (SAT-TUE)...
HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER THE WEEKEND
WITH TEMPERATURES WARMING AND THE MARINE LAYER BECOMING LESS OF AN
ISSUE FOR COASTAL AREAS. VERY LITTLE SIGNIFICANT WEATHER ISSUES
THROUGH TUESDAY. REMNANT MOISTURE FROM TWO TROPICAL SYSTEMS (LOWELL
AND KARINA) COULD GET PULLED NORTHWARD CLOSER TO SOUTHERN CALI BY
MONDAY OR TUESDAY. WOULD ONLY EXPECT SOME MID TO HIGH LEVEL CLOUDS
FROM THESE SYSTEMS AT BEST WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...19/2320Z.
UPPER LOW NEAR POINT CONCEPTION WILL CONTINUE TO MAINTAIN A DEEP MARINE
LAYER THROUGH PERIOD...RISING TO AROUND 4000 FEET ACROSS AREAS SOUTH OF
POINT CONCEPTION BY WEDNESDAY MORNING. EXPECTING MVFR CIGS TO BE
MORE WIDESPREAD ACROSS COASTAL/VALLEY TAF LOCATIONS TONIGHT...WITH LOWEST
CONFIDENCE IN TIMING ACROSS LA COUNTY. THERE IS A CHANCE OF DRIZZLE
OVERNIGHT ACROSS COASTAL/VALLEY LOCATIONS. THEN ON WEDNESDAY...THERE
WILL BE A 20 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL OF
LA COUNTY AS WELL AS THE VENTURA COUNTY MOUNTAINS.

KLAX AND KBUR...POOR CONFIDENCE IN ARRIVAL TIME OF MVFR CIGS
TONIGHT. IF LOW CLOUDS DEVELOP...THERE WILL BE A CHANCE OF DRIZZLE
OVERNIGHT. AS LOW DRAWS CLOSER...THERE WILL BE A 20 PERCENT CHANCE
OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY.

&&

.MARINE...19/200 PM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...GOMBERG/SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES









000
FXUS66 KLOX 192323
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
425 PM PDT TUE AUG 19 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.SHORT TERM (TONIGHT-FRI)...
FORECAST CONCERNS IN THIS PACKAGE...MARINE LAYER/CLOUDS AND SLIGHT
CHANCE OF CONVECTION THROUGH THURSDAY AFTERNOON.

UPPER LOW CONTINUES TO DROP SOUTHWARD ALONG THE CENTRAL COAST THIS
AFTERNOON AND WILL BE OVER THE CHANNEL ISLANDS WEDNESDAY
MORNING...THEN SHIFT TO THE HIGHER DESERTS ON THURSDAY. THIS IS A
RATHER STRONG LOW PRESSURE AREA FOR THIS TIME OF THE YEAR AND SOME
COOL AIR ALOFT IS ASSOCIATED WITH IT. THE MAIN PROBLEM WITH THIS
SYSTEM IS A LACK OF ADEQUATE MOISTURE ACROSS SOUTHWEST CALI AND NOT
MUCH OF A FETCH TO ADVECT MOISTURE FROM THE OCEAN. HOWEVER...UPPER
LOWS ARE NOTORIOUS FOR GENERATING PRECIPITATION OUT OF RATHER POOR
ATMOSPHERIC MOISTURE CONTENT.

INSTABILITY WITH THIS SYSTEM IS NOT LACKING...8 DEGREE C LAPSE RATES
BETWEEN 700-500MB...NEGATIVE LIFTED INDEX...SURFACE CAPE...AND
CYCLONIC FLOW WITH DIVERGENCE ALOFT. OTHER ISSUE IS MARINE LAYER
WILL REMAIN VERY THICK OVER 3K FEET. WRF CONTINUES TO SHOW
INCREASING INSTABILITY OVER THE SOUTH COASTAL WATERS AND LA BASIN
WEDNESDAY MORNING. COULD SEE LIGHTNING AT SAME TIME OF LOW CLOUD
COVER DURING MORNING COMMUTE. BEST MOISTURE PLUME SWINGS ACROSS SAN
DIEGO COUNTY AND NOSES BACK INTO THE LA COUNTY MOUNTAINS WEDNESDAY
AFTERNOON. THIS WILL BE OUR BEST FOCUS FOR THUNDERSTORMS TOMORROW
WITH MAINLY LINGERING LIGHT SHOWERS ACROSS THE COAST AND VALLEYS OF
LOS ANGELES COUNTY. TEMPERATURES WILL REMAIN STUNTED BELOW NORMAL ON
WEDNESDAY...RUNNING A GOOD 10-20 DEGREES COOLER TODAY COMPARED TO
YESTERDAY.

THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS ON THURSDAY. THE
LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER THE EASTERN SAN
GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF THUNDERSTORMS. A
SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY MORNING BUT WILL STILL
SEE LOW CLOUDS FOR COASTS AND NEARBY VALLEYS TO START THE DAY. BY
FRIDAY MORNING THE MARINE LAYER SHRINKS EVEN MORE AND MAY ONLY SEE
PATCHY CLOUDS SOUTH OF PT CONCEPTION. TEMPERATURES WILL START TO
REBOUND LATE IN THE WEEK BUT A LARGE SCALE UPPER TROUGH ACROSS MOST
OF THE WEST WILL SLOW ANY SIGNIFICANT WARMING UNTIL LATER IN THE
WEEKEND.

.LONG TERM (SAT-TUE)...
HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER THE WEEKEND
WITH TEMPERATURES WARMING AND THE MARINE LAYER BECOMING LESS OF AN
ISSUE FOR COASTAL AREAS. VERY LITTLE SIGNIFICANT WEATHER ISSUES
THROUGH TUESDAY. REMNANT MOISTURE FROM TWO TROPICAL SYSTEMS (LOWELL
AND KARINA) COULD GET PULLED NORTHWARD CLOSER TO SOUTHERN CALI BY
MONDAY OR TUESDAY. WOULD ONLY EXPECT SOME MID TO HIGH LEVEL CLOUDS
FROM THESE SYSTEMS AT BEST WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...19/2320Z.
UPPER LOW NEAR POINT CONCEPTION WILL CONTINUE TO MAINTAIN A DEEP MARINE
LAYER THROUGH PERIOD...RISING TO AROUND 4000 FEET ACROSS AREAS SOUTH OF
POINT CONCEPTION BY WEDNESDAY MORNING. EXPECTING MVFR CIGS TO BE
MORE WIDESPREAD ACROSS COASTAL/VALLEY TAF LOCATIONS TONIGHT...WITH LOWEST
CONFIDENCE IN TIMING ACROSS LA COUNTY. THERE IS A CHANCE OF DRIZZLE
OVERNIGHT ACROSS COASTAL/VALLEY LOCATIONS. THEN ON WEDNESDAY...THERE
WILL BE A 20 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS FOR ALL OF
LA COUNTY AS WELL AS THE VENTURA COUNTY MOUNTAINS.

KLAX AND KBUR...POOR CONFIDENCE IN ARRIVAL TIME OF MVFR CIGS
TONIGHT. IF LOW CLOUDS DEVELOP...THERE WILL BE A CHANCE OF DRIZZLE
OVERNIGHT. AS LOW DRAWS CLOSER...THERE WILL BE A 20 PERCENT CHANCE
OF SHOWERS AND THUNDERSTORMS ON WEDNESDAY.

&&

.MARINE...19/200 PM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...GOMBERG/SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES










000
FXUS66 KLOX 192053
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
150 PM PDT TUE AUG 19 2014

.SYNOPSIS...

THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.SHORT TERM (TONIGHT-FRI)...
FORECAST CONCERNS IN THIS PACKAGE...MARINE LAYER/CLOUDS AND SLIGHT
CHANCE OF CONVECTION THROUGH THURSDAY AFTERNOON.

UPPER LOW CONTINUES TO DROP SOUTHWARD ALONG THE CENTRAL COAST THIS
AFTERNOON AND WILL BE OVER THE CHANNEL ISLANDS WEDNESDAY
MORNING...THEN SHIFT TO THE HIGHER DESERTS ON THURSDAY. THIS IS A
RATHER STRONG LOW PRESSURE AREA FOR THIS TIME OF THE YEAR AND SOME
COOL AIR ALOFT IS ASSOCIATED WITH IT. THE MAIN PROBLEM WITH THIS
SYSTEM IS A LACK OF ADEQUATE MOISTURE ACROSS SOUTHWEST CALI AND NOT
MUCH OF A FETCH TO ADVECT MOISTURE FROM THE OCEAN. HOWEVER...UPPER
LOWS ARE NOTORIOUS FOR GENERATING PRECIPITATION OUT OF RATHER POOR
ATMOSPHERIC MOISTURE CONTENT.

INSTABILITY WITH THIS SYSTEM IS NOT LACKING...8 DEGREE C LAPSE RATES
BETWEEN 700-500MB...NEGATIVE LIFTED INDEX...SURFACE CAPE...AND
CYCLONIC FLOW WITH DIVERGENCE ALOFT. OTHER ISSUE IS MARINE LAYER
WILL REMAIN VERY THICK OVER 3K FEET. WRF CONTINUES TO SHOW
INCREASING INSTABILITY OVER THE SOUTH COASTAL WATERS AND LA BASIN
WEDNESDAY MORNING. COULD SEE LIGHTNING AT SAME TIME OF LOW CLOUD
COVER DURING MORNING COMMUTE. BEST MOISTURE PLUME SWINGS ACROSS SAN
DIEGO COUNTY AND NOSES BACK INTO THE LA COUNTY MOUNTAINS WEDNESDAY
AFTERNOON. THIS WILL BE OUR BEST FOCUS FOR THUNDERSTORMS TOMORROW
WITH MAINLY LINGERING LIGHT SHOWERS ACROSS THE COAST AND VALLEYS OF
LOS ANGELES COUNTY. TEMPERATURES WILL REMAIN STUNTED BELOW NORMAL ON
WEDNESDAY...RUNNING A GOOD 10-20 DEGREES COOLER TODAY COMPARED TO
YESTERDAY.

THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS ON THURSDAY. THE
LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER THE EASTERN SAN
GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF THUNDERSTORMS. A
SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY MORNING BUT WILL STILL
SEE LOW CLOUDS FOR COASTS AND NEARBY VALLEYS TO START THE DAY. BY
FRIDAY MORNING THE MARINE LAYER SHRINKS EVEN MORE AND MAY ONLY SEE
PATCHY CLOUDS SOUTH OF PT CONCEPTION. TEMPERATURES WILL START TO
REBOUND LATE IN THE WEEK BUT A LARGE SCALE UPPER TROUGH ACROSS MOST
OF THE WEST WILL SLOW ANY SIGNIFICANT WARMING UNTIL LATER IN THE
WEEKEND.

.LONG TERM (SAT-TUE)...
HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER THE WEEKEND
WITH TEMPERATURES WARMING AND THE MARINE LAYER BECOMING LESS OF AN
ISSUE FOR COASTAL AREAS. VERY LITTLE SIGNIFICANT WEATHER ISSUES
THROUGH TUESDAY. REMNANT MOISTURE FROM TWO TROPICAL SYSTEMS (LOWELL
AND KARINA) COULD GET PULLED NORTHWARD CLOSER TO SOUTHERN CALI BY
MONDAY OR TUESDAY. WOULD ONLY EXPECT SOME MID TO HIGH LEVEL CLOUDS
FROM THESE SYSTEMS AT BEST WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...19/1800Z.
SOME RESERVATIONS ABOUT THE NEXT 24 HOURS...YET STILL DECIDED ON THE
HIGH PERCENTAGE FORECAST OF ANOTHER ROUND OF MARINE CLOUDS FOR LATE
TONIGHT INTO WEDNESDAY MORNING AND A CONTINUED DEEP MARINE LAYER.
SOME CONCERN THAT THE MARINE LAYER WILL BREAK UP AND BECOME LESS
PREVALENT SO THE CONFIDENCE IS ON THE LOW SIDE.

KLAX AND KBUR...POOR CONFIDENCE IN THE 18Z TAF. THERE IS A 30 TO 40
PERCENT CHANCE THAT THE MARINE CLOUDS WILL NOT LAST ALL NIGHT.

&&

.MARINE...19/200 PM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES







000
FXUS66 KLOX 192053
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
150 PM PDT TUE AUG 19 2014

.SYNOPSIS...

THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.SHORT TERM (TONIGHT-FRI)...
FORECAST CONCERNS IN THIS PACKAGE...MARINE LAYER/CLOUDS AND SLIGHT
CHANCE OF CONVECTION THROUGH THURSDAY AFTERNOON.

UPPER LOW CONTINUES TO DROP SOUTHWARD ALONG THE CENTRAL COAST THIS
AFTERNOON AND WILL BE OVER THE CHANNEL ISLANDS WEDNESDAY
MORNING...THEN SHIFT TO THE HIGHER DESERTS ON THURSDAY. THIS IS A
RATHER STRONG LOW PRESSURE AREA FOR THIS TIME OF THE YEAR AND SOME
COOL AIR ALOFT IS ASSOCIATED WITH IT. THE MAIN PROBLEM WITH THIS
SYSTEM IS A LACK OF ADEQUATE MOISTURE ACROSS SOUTHWEST CALI AND NOT
MUCH OF A FETCH TO ADVECT MOISTURE FROM THE OCEAN. HOWEVER...UPPER
LOWS ARE NOTORIOUS FOR GENERATING PRECIPITATION OUT OF RATHER POOR
ATMOSPHERIC MOISTURE CONTENT.

INSTABILITY WITH THIS SYSTEM IS NOT LACKING...8 DEGREE C LAPSE RATES
BETWEEN 700-500MB...NEGATIVE LIFTED INDEX...SURFACE CAPE...AND
CYCLONIC FLOW WITH DIVERGENCE ALOFT. OTHER ISSUE IS MARINE LAYER
WILL REMAIN VERY THICK OVER 3K FEET. WRF CONTINUES TO SHOW
INCREASING INSTABILITY OVER THE SOUTH COASTAL WATERS AND LA BASIN
WEDNESDAY MORNING. COULD SEE LIGHTNING AT SAME TIME OF LOW CLOUD
COVER DURING MORNING COMMUTE. BEST MOISTURE PLUME SWINGS ACROSS SAN
DIEGO COUNTY AND NOSES BACK INTO THE LA COUNTY MOUNTAINS WEDNESDAY
AFTERNOON. THIS WILL BE OUR BEST FOCUS FOR THUNDERSTORMS TOMORROW
WITH MAINLY LINGERING LIGHT SHOWERS ACROSS THE COAST AND VALLEYS OF
LOS ANGELES COUNTY. TEMPERATURES WILL REMAIN STUNTED BELOW NORMAL ON
WEDNESDAY...RUNNING A GOOD 10-20 DEGREES COOLER TODAY COMPARED TO
YESTERDAY.

THE UPPER LOW MOVES SOUTHEAST TO THE HIGH DESERTS ON THURSDAY. THE
LAST BIT OF INSTABILITY AND MOISTURE WILL BE OVER THE EASTERN SAN
GABRIEL MOUNTAINS FOR A CONTINUED SLIGHT CHANCE OF THUNDERSTORMS. A
SHALLOWER MARINE LAYER IS LIKELY ON THURSDAY MORNING BUT WILL STILL
SEE LOW CLOUDS FOR COASTS AND NEARBY VALLEYS TO START THE DAY. BY
FRIDAY MORNING THE MARINE LAYER SHRINKS EVEN MORE AND MAY ONLY SEE
PATCHY CLOUDS SOUTH OF PT CONCEPTION. TEMPERATURES WILL START TO
REBOUND LATE IN THE WEEK BUT A LARGE SCALE UPPER TROUGH ACROSS MOST
OF THE WEST WILL SLOW ANY SIGNIFICANT WARMING UNTIL LATER IN THE
WEEKEND.

.LONG TERM (SAT-TUE)...
HIGH PRESSURE SLOWLY BUILDS ACROSS THE SOUTHWEST OVER THE WEEKEND
WITH TEMPERATURES WARMING AND THE MARINE LAYER BECOMING LESS OF AN
ISSUE FOR COASTAL AREAS. VERY LITTLE SIGNIFICANT WEATHER ISSUES
THROUGH TUESDAY. REMNANT MOISTURE FROM TWO TROPICAL SYSTEMS (LOWELL
AND KARINA) COULD GET PULLED NORTHWARD CLOSER TO SOUTHERN CALI BY
MONDAY OR TUESDAY. WOULD ONLY EXPECT SOME MID TO HIGH LEVEL CLOUDS
FROM THESE SYSTEMS AT BEST WITH LITTLE EFFECT ON TEMPERATURES.

&&

.AVIATION...19/1800Z.
SOME RESERVATIONS ABOUT THE NEXT 24 HOURS...YET STILL DECIDED ON THE
HIGH PERCENTAGE FORECAST OF ANOTHER ROUND OF MARINE CLOUDS FOR LATE
TONIGHT INTO WEDNESDAY MORNING AND A CONTINUED DEEP MARINE LAYER.
SOME CONCERN THAT THE MARINE LAYER WILL BREAK UP AND BECOME LESS
PREVALENT SO THE CONFIDENCE IS ON THE LOW SIDE.

KLAX AND KBUR...POOR CONFIDENCE IN THE 18Z TAF. THERE IS A 30 TO 40
PERCENT CHANCE THAT THE MARINE CLOUDS WILL NOT LAST ALL NIGHT.

&&

.MARINE...19/200 PM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES






000
FXUS66 KLOX 191908
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1210 PM PDT TUE AUG 19 2014

...NEW AVIATION DISCUSSION...

.SYNOPSIS...
THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.UPDATE...
FORECAST CONCERNS TODAY WILL BE LOW CLOUDS PERSISTING AT THE BEACHES
AND THREAT OF MOUNTAIN CONVECTION.

UPPER LOW WAS NEAR MONTEREY BAY THIS MORNING AND WILL DROP SOUTHWARD
TO THE CHANNEL ISLANDS THIS EVENING. THE ONLY PRECIPITATION
GENERATED WITH THE LOW OVERNIGHT WAS A LITTLE DRIZZLE IN THE BAY
AREA BUT OUR REGION REMAINED DRY. MARINE LAYER JUMPED UP OVER 3000
FEET LAST NIGHT ACCORDING TO LAX ACARS DATA. THIS RESULTED IN LOW
CLOUDS PUSHING WELL INTO THE VALLEYS BUT JUST SHORT OF THE SANTA
CLARITA VALLEY. ONSHORE PRESSURE GRADIENTS ARE OVER 2 MB STRONGER
THAN YESTERDAY AND EXPECTED TO TOP OUT BETWEEN 7-8MB BETWEEN LAX-DAG
THIS AFTERNOON. BREEZY CONDITIONS AND MANY DEGREES OF COOLING WILL
BE THE MAIN THEME TODAY...SOME INTERIOR VALLEY AND MOUNTAIN AREA
WILL SEE A 15 DEGREE DROP FROM YESTERDAYS HIGHS.

THE OTHER ISSUE TODAY IS THE POTENTIAL FOR THUNDERSTORMS IN THE
SANTA BARBARA AND VENTURA COUNTY MOUNTAINS. THERE ARE SEVERAL
FACTORS IN FAVOR...DIFFLUENT AREA AHEAD OF THE UPPER LOW...STEEP
LAPSE RATES AND SURFACE CAPE...AND COLDER AIR ALOFT ADVECTING INTO
THE AREA. BUT THEN THERE ARE UNFAVORABLE CONDITIONS...NO CONVECTIVE
HISTORY IN LAST 18 HOURS...VERY LIMITED AVAILABLE MOISTURE...WRONG
JET QUADRANT...AND NEGATIVE ENERGY OR CIN TO OVERCOME. ONLY HAVE
SLIGHT CHANCE FOR THESE AREAS BUT MAIN PROBABILITY IS FOR HIGH-BASED
TOWERING CUMULUS OVER THE MOUNTAINS. IF A THUNDERSTORM GETS
ORGANIZED IT WOULD MOVE QUICKLY AND LIKELY GENERATE DOWNBURST WIND
GUSTS AND LITTLE RAINFALL. CLOSED UPPER LOWS TRACKING JUST ALONG THE
COAST ARE THE MOST DIFFICULT TO PREDICT FOR MOISTURE CONTENT...THIS
ONE WILL CHALLENGE FORECASTS THROUGH WEDNESDAY.

***FROM PREVIOUS DISCUSSION***

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...19/1800Z.
SOME RESERVATIONS ABOUT THE NEXT 24 HOURS...YET STILL DECIDED ON THE
HIGH PERCENTAGE FORECAST OF ANOTHER ROUND OF MARINE CLOUDS FOR LATE
TONIGHT INTO WEDNESDAY MORNING AND A CONTINUED DEEP MARINE LAYER.
SOME CONCERN THAT THE MARINE LAYER WILL BREAK UP AND BECOME LESS
PREVALENT SO THE CONFIDENCE IS ON THE LOW SIDE.

KLAX AND KBUR...POOR CONFIDENCE IN THE 18Z TAF. THERE IS A 30 TO 40
PERCENT CHANCE THAT THE MARINE CLOUDS WILL NOT LAST ALL NIGHT.

&&

.MARINE...19/900 AM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...SWEET
SYNOPSIS...DUMAS

WWW.WEATHER.GOV/LOSANGELES















000
FXUS66 KLOX 191908
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1210 PM PDT TUE AUG 19 2014

...NEW AVIATION DISCUSSION...

.SYNOPSIS...
THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.UPDATE...
FORECAST CONCERNS TODAY WILL BE LOW CLOUDS PERSISTING AT THE BEACHES
AND THREAT OF MOUNTAIN CONVECTION.

UPPER LOW WAS NEAR MONTEREY BAY THIS MORNING AND WILL DROP SOUTHWARD
TO THE CHANNEL ISLANDS THIS EVENING. THE ONLY PRECIPITATION
GENERATED WITH THE LOW OVERNIGHT WAS A LITTLE DRIZZLE IN THE BAY
AREA BUT OUR REGION REMAINED DRY. MARINE LAYER JUMPED UP OVER 3000
FEET LAST NIGHT ACCORDING TO LAX ACARS DATA. THIS RESULTED IN LOW
CLOUDS PUSHING WELL INTO THE VALLEYS BUT JUST SHORT OF THE SANTA
CLARITA VALLEY. ONSHORE PRESSURE GRADIENTS ARE OVER 2 MB STRONGER
THAN YESTERDAY AND EXPECTED TO TOP OUT BETWEEN 7-8MB BETWEEN LAX-DAG
THIS AFTERNOON. BREEZY CONDITIONS AND MANY DEGREES OF COOLING WILL
BE THE MAIN THEME TODAY...SOME INTERIOR VALLEY AND MOUNTAIN AREA
WILL SEE A 15 DEGREE DROP FROM YESTERDAYS HIGHS.

THE OTHER ISSUE TODAY IS THE POTENTIAL FOR THUNDERSTORMS IN THE
SANTA BARBARA AND VENTURA COUNTY MOUNTAINS. THERE ARE SEVERAL
FACTORS IN FAVOR...DIFFLUENT AREA AHEAD OF THE UPPER LOW...STEEP
LAPSE RATES AND SURFACE CAPE...AND COLDER AIR ALOFT ADVECTING INTO
THE AREA. BUT THEN THERE ARE UNFAVORABLE CONDITIONS...NO CONVECTIVE
HISTORY IN LAST 18 HOURS...VERY LIMITED AVAILABLE MOISTURE...WRONG
JET QUADRANT...AND NEGATIVE ENERGY OR CIN TO OVERCOME. ONLY HAVE
SLIGHT CHANCE FOR THESE AREAS BUT MAIN PROBABILITY IS FOR HIGH-BASED
TOWERING CUMULUS OVER THE MOUNTAINS. IF A THUNDERSTORM GETS
ORGANIZED IT WOULD MOVE QUICKLY AND LIKELY GENERATE DOWNBURST WIND
GUSTS AND LITTLE RAINFALL. CLOSED UPPER LOWS TRACKING JUST ALONG THE
COAST ARE THE MOST DIFFICULT TO PREDICT FOR MOISTURE CONTENT...THIS
ONE WILL CHALLENGE FORECASTS THROUGH WEDNESDAY.

***FROM PREVIOUS DISCUSSION***

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...19/1800Z.
SOME RESERVATIONS ABOUT THE NEXT 24 HOURS...YET STILL DECIDED ON THE
HIGH PERCENTAGE FORECAST OF ANOTHER ROUND OF MARINE CLOUDS FOR LATE
TONIGHT INTO WEDNESDAY MORNING AND A CONTINUED DEEP MARINE LAYER.
SOME CONCERN THAT THE MARINE LAYER WILL BREAK UP AND BECOME LESS
PREVALENT SO THE CONFIDENCE IS ON THE LOW SIDE.

KLAX AND KBUR...POOR CONFIDENCE IN THE 18Z TAF. THERE IS A 30 TO 40
PERCENT CHANCE THAT THE MARINE CLOUDS WILL NOT LAST ALL NIGHT.

&&

.MARINE...19/900 AM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...SWEET
SYNOPSIS...DUMAS

WWW.WEATHER.GOV/LOSANGELES
















000
FXUS66 KLOX 191643
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
940 AM PDT TUE AUG 19 2014

.SYNOPSIS...
THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.UPDATE...
FORECAST CONCERNS TODAY WILL BE LOW CLOUDS PERSISTING AT THE BEACHES
AND THREAT OF MOUNTAIN CONVECTION.

UPPER LOW WAS NEAR MONTEREY BAY THIS MORNING AND WILL DROP SOUTHWARD
TO THE CHANNEL ISLANDS THIS EVENING. THE ONLY PRECIPITATION
GENERATED WITH THE LOW OVERNIGHT WAS A LITTLE DRIZZLE IN THE BAY
AREA BUT OUR REGION REMAINED DRY. MARINE LAYER JUMPED UP OVER 3000
FEET LAST NIGHT ACCORDING TO LAX ACARS DATA. THIS RESULTED IN LOW
CLOUDS PUSHING WELL INTO THE VALLEYS BUT JUST SHORT OF THE SANTA
CLARITA VALLEY. ONSHORE PRESSURE GRADIENTS ARE OVER 2 MB STRONGER
THAN YESTERDAY AND EXPECTED TO TOP OUT BETWEEN 7-8MB BETWEEN LAX-DAG
THIS AFTERNOON. BREEZY CONDITIONS AND MANY DEGREES OF COOLING WILL
BE THE MAIN THEME TODAY...SOME INTERIOR VALLEY AND MOUNTAIN AREA
WILL SEE A 15 DEGREE DROP FROM YESTERDAYS HIGHS.

THE OTHER ISSUE TODAY IS THE POTENTIAL FOR THUNDERSTORMS IN THE
SANTA BARBARA AND VENTURA COUNTY MOUNTAINS. THERE ARE SEVERAL
FACTORS IN FAVOR...DIFFLUENT AREA AHEAD OF THE UPPER LOW...STEEP
LAPSE RATES AND SURFACE CAPE...AND COLDER AIR ALOFT ADVECTING INTO
THE AREA. BUT THEN THERE ARE UNFAVORABLE CONDITIONS...NO CONVECTIVE
HISTORY IN LAST 18 HOURS...VERY LIMITED AVAILABLE MOISTURE...WRONG
JET QUADRANT...AND NEGATIVE ENERGY OR CIN TO OVERCOME. ONLY HAVE
SLIGHT CHANCE FOR THESE AREAS BUT MAIN PROBABILITY IS FOR HIGH-BASED
TOWERING CUMULUS OVER THE MOUNTAINS. IF A THUNDERSTORM GETS
ORGANIZED IT WOULD MOVE QUICKLY AND LIKELY GENERATE DOWNBURST WIND
GUSTS AND LITTLE RAINFALL. CLOSED UPPER LOWS TRACKING JUST ALONG THE
COAST ARE THE MOST DIFFICULT TO PREDICT FOR MOISTURE CONTENT...THIS
ONE WILL CHALLENGE FORECASTS THROUGH WEDNESDAY.

***FROM PREVIOUS DISCUSSION***

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...

19/1130Z

WIDESPREAD STRATUS IN ALL COASTAL AND MOST VLYS AREAS THIS MORNING
SHOULD PUSH INTO REMAINDER OF THE VLYS BY DAYBREAK. CONDS MOSTLY
MVFR...EXCEPT IFR ACROSS SLO/SBA COUNTIES AND IN THE FOOTHILLS
THROUGH MID MORNING. COULD BE SOME DRIZZLE THIS MORNING...MAINLY IN
COASTAL/VLY AREAS OF VTU/L.A. COUNTIES. EXPECT SLOW CLEARING
TODAY...ESPECIALLY NEAR THE COAST...AND CIGS MAY LINGER THRU THE
DAY...ESPECIALLY ON THE S COAST OF SBA COUNTY AND THE VTU COUNTY
COAST. EXPECT AN EARLY RETURN OF LOW CLDS TO MOST AREAS THIS EVENING.

KLAX...MODERATE CONFIDENCE IN THE 12Z TAF. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY. THERE IS
A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS BETWEEN
13Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT BURN OFF UNTIL AT LEAST 20Z.
THERE IS A 20 PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER
06Z ON THE 20TH (TONIGHT)

&&

.MARINE...19/900 AM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...SWEET/DB
SYNOPSIS...DUMAS

WWW.WEATHER.GOV/LOSANGELES













000
FXUS66 KLOX 191643
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
940 AM PDT TUE AUG 19 2014

.SYNOPSIS...
THE LARGE UPPER LEVEL LOW ARRIVES TODAY FROM THE NORTH AND WILL
INCREASE NIGHT TO MORNING CLOUDS AND FOG THROUGH SATURDAY...ONSHORE
FLOW...DRIZZLE AND COOLING TREND...ESPECIALLY INLAND...ISOLATED
MOUNTAIN SHOWERS OR THUNDERSTORMS ARE POSSIBLE. SUBTROPICAL MOISTURE
AND CHANCE OF AFTERNOON MOUNTAIN THUNDERSTORMS LATER IN THE WEEK.

&&

.UPDATE...
FORECAST CONCERNS TODAY WILL BE LOW CLOUDS PERSISTING AT THE BEACHES
AND THREAT OF MOUNTAIN CONVECTION.

UPPER LOW WAS NEAR MONTEREY BAY THIS MORNING AND WILL DROP SOUTHWARD
TO THE CHANNEL ISLANDS THIS EVENING. THE ONLY PRECIPITATION
GENERATED WITH THE LOW OVERNIGHT WAS A LITTLE DRIZZLE IN THE BAY
AREA BUT OUR REGION REMAINED DRY. MARINE LAYER JUMPED UP OVER 3000
FEET LAST NIGHT ACCORDING TO LAX ACARS DATA. THIS RESULTED IN LOW
CLOUDS PUSHING WELL INTO THE VALLEYS BUT JUST SHORT OF THE SANTA
CLARITA VALLEY. ONSHORE PRESSURE GRADIENTS ARE OVER 2 MB STRONGER
THAN YESTERDAY AND EXPECTED TO TOP OUT BETWEEN 7-8MB BETWEEN LAX-DAG
THIS AFTERNOON. BREEZY CONDITIONS AND MANY DEGREES OF COOLING WILL
BE THE MAIN THEME TODAY...SOME INTERIOR VALLEY AND MOUNTAIN AREA
WILL SEE A 15 DEGREE DROP FROM YESTERDAYS HIGHS.

THE OTHER ISSUE TODAY IS THE POTENTIAL FOR THUNDERSTORMS IN THE
SANTA BARBARA AND VENTURA COUNTY MOUNTAINS. THERE ARE SEVERAL
FACTORS IN FAVOR...DIFFLUENT AREA AHEAD OF THE UPPER LOW...STEEP
LAPSE RATES AND SURFACE CAPE...AND COLDER AIR ALOFT ADVECTING INTO
THE AREA. BUT THEN THERE ARE UNFAVORABLE CONDITIONS...NO CONVECTIVE
HISTORY IN LAST 18 HOURS...VERY LIMITED AVAILABLE MOISTURE...WRONG
JET QUADRANT...AND NEGATIVE ENERGY OR CIN TO OVERCOME. ONLY HAVE
SLIGHT CHANCE FOR THESE AREAS BUT MAIN PROBABILITY IS FOR HIGH-BASED
TOWERING CUMULUS OVER THE MOUNTAINS. IF A THUNDERSTORM GETS
ORGANIZED IT WOULD MOVE QUICKLY AND LIKELY GENERATE DOWNBURST WIND
GUSTS AND LITTLE RAINFALL. CLOSED UPPER LOWS TRACKING JUST ALONG THE
COAST ARE THE MOST DIFFICULT TO PREDICT FOR MOISTURE CONTENT...THIS
ONE WILL CHALLENGE FORECASTS THROUGH WEDNESDAY.

***FROM PREVIOUS DISCUSSION***

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...

19/1130Z

WIDESPREAD STRATUS IN ALL COASTAL AND MOST VLYS AREAS THIS MORNING
SHOULD PUSH INTO REMAINDER OF THE VLYS BY DAYBREAK. CONDS MOSTLY
MVFR...EXCEPT IFR ACROSS SLO/SBA COUNTIES AND IN THE FOOTHILLS
THROUGH MID MORNING. COULD BE SOME DRIZZLE THIS MORNING...MAINLY IN
COASTAL/VLY AREAS OF VTU/L.A. COUNTIES. EXPECT SLOW CLEARING
TODAY...ESPECIALLY NEAR THE COAST...AND CIGS MAY LINGER THRU THE
DAY...ESPECIALLY ON THE S COAST OF SBA COUNTY AND THE VTU COUNTY
COAST. EXPECT AN EARLY RETURN OF LOW CLDS TO MOST AREAS THIS EVENING.

KLAX...MODERATE CONFIDENCE IN THE 12Z TAF. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY. THERE IS
A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS BETWEEN
13Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT BURN OFF UNTIL AT LEAST 20Z.
THERE IS A 20 PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER
06Z ON THE 20TH (TONIGHT)

&&

.MARINE...19/900 AM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...SWEET/DB
SYNOPSIS...DUMAS

WWW.WEATHER.GOV/LOSANGELES












000
FXUS66 KLOX 191128
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
430 AM PDT TUE AUG 19 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TODAY-THU)...
2400 FOOT MARINE LAYER WITH LOW CLOUDS ACROSS ALL COASTS AND VLYS
EXCEPT THE SANTA CLARITA AND VENTURA VLYS. THE CLOUDS SHOULD FILL
INTO THESE AREAS BY DAWN. THE LIFTING OF THE MARINE LAYER SHOULD BE
ENOUGH TO PRODUCE SOME DRIZZLE...ESP NEAR THE FOOTHILLS. KDAG
GRADIENT WILL SURGE TO OVER 8 MB THIS AFTERNOON AND THIS WILL MAKE
CLEARING SLOWER THAN NORMAL AND WILL ALSO LIKELY KEEP SOME CLOUDS AT
THE BEACHES. ALL OF THIS LIFT COMES COURTESY OF AN UPPER LOW JUST
WEST OF MONTERREY. BY AFTERNOON THE LOW WILL BE NEAR POINT
CONCEPTION THE COOL POOL OF AIR ALOFT AND A WEAK VORT MAX SHOULD BE
ENOUGH TO CREATE A SLIGHT CHC OF A TSTM OVER THE VTA AND SBA MTNS
THIS AFTERNOON. MAX TEMPS WILL BE BLO NORMAL HAS HGTS FALL THROUGH
THE DAY ALONG WITH THE DEEP MARINE LAYER AND STRONGER THAN NORMAL
ONSHORE FLOW. THIS STRONG ONSHORE FLOW TO KDAG WILL ALSO CREATE NEAR
ADVISORY LEVEL WINDS ACROSS PART OF THE ANTELOPE VLY ESP THE LAKE
PALMDALE AREA.

THE UPPER LOW WILL SIT ATOP OF VENTURA COUNTY. WHAT THE CLOUD FIELD
IS GOING TO LOOK LIKE IS A RATHER TRICKY PROPOSITION. RIGHT NOW HAVE
A DEEP MARINE LAYER WITH A CLOUD PATTER COVERING THE COASTS AND
VLYS. THIS IS THE MOSTLY LIKELY SCENARIO BUT IT IS NOT DIFFICULT TO
IMAGINE THE UPR LOW WREAKING HAVOC WITH THE MARINE INVERSION AND
CONSEQUENTLY THE LOW CLOUDS. IF THE MARINE LAYER STAYS AS DEEP AS IT
MORE DRIZZLE WILL ALSO BE POSSIBLE/

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...

19/1130Z

WIDESPREAD STRATUS IN ALL COASTAL AND MOST VLYS AREAS THIS MORNING
SHOULD PUSH INTO REMAINDER OF THE VLYS BY DAYBREAK. CONDS MOSTLY
MVFR...EXCEPT IFR ACROSS SLO/SBA COUNTIES AND IN THE FOOTHILLS
THROUGH MID MORNING. COULD BE SOME DRIZZLE THIS MORNING...MAINLY IN
COASTAL/VLY AREAS OF VTU/L.A. COUNTIES. EXPECT SLOW CLEARING
TODAY...ESPECIALLY NEAR THE COAST...AND CIGS MAY LINGER THRU THE
DAY...ESPECIALLY ON THE S COAST OF SBA COUNTY AND THE VTU COUNTY
COAST. EXPECT AN EARLY RETURN OF LOW CLDS TO MOST AREAS THIS EVENING.

KLAX...MODERATE CONFIDENCE IN THE 12Z TAF. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY. THERE IS
A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS BETWEEN
13Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT BURN OFF UNTIL AT LEAST 20Z.
THERE IS A 20 PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER
06Z ON THE 20TH (TONIGHT)

&&

.MARINE...18/900 PM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...DB
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES









000
FXUS66 KLOX 191128
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
430 AM PDT TUE AUG 19 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TODAY-THU)...
2400 FOOT MARINE LAYER WITH LOW CLOUDS ACROSS ALL COASTS AND VLYS
EXCEPT THE SANTA CLARITA AND VENTURA VLYS. THE CLOUDS SHOULD FILL
INTO THESE AREAS BY DAWN. THE LIFTING OF THE MARINE LAYER SHOULD BE
ENOUGH TO PRODUCE SOME DRIZZLE...ESP NEAR THE FOOTHILLS. KDAG
GRADIENT WILL SURGE TO OVER 8 MB THIS AFTERNOON AND THIS WILL MAKE
CLEARING SLOWER THAN NORMAL AND WILL ALSO LIKELY KEEP SOME CLOUDS AT
THE BEACHES. ALL OF THIS LIFT COMES COURTESY OF AN UPPER LOW JUST
WEST OF MONTERREY. BY AFTERNOON THE LOW WILL BE NEAR POINT
CONCEPTION THE COOL POOL OF AIR ALOFT AND A WEAK VORT MAX SHOULD BE
ENOUGH TO CREATE A SLIGHT CHC OF A TSTM OVER THE VTA AND SBA MTNS
THIS AFTERNOON. MAX TEMPS WILL BE BLO NORMAL HAS HGTS FALL THROUGH
THE DAY ALONG WITH THE DEEP MARINE LAYER AND STRONGER THAN NORMAL
ONSHORE FLOW. THIS STRONG ONSHORE FLOW TO KDAG WILL ALSO CREATE NEAR
ADVISORY LEVEL WINDS ACROSS PART OF THE ANTELOPE VLY ESP THE LAKE
PALMDALE AREA.

THE UPPER LOW WILL SIT ATOP OF VENTURA COUNTY. WHAT THE CLOUD FIELD
IS GOING TO LOOK LIKE IS A RATHER TRICKY PROPOSITION. RIGHT NOW HAVE
A DEEP MARINE LAYER WITH A CLOUD PATTER COVERING THE COASTS AND
VLYS. THIS IS THE MOSTLY LIKELY SCENARIO BUT IT IS NOT DIFFICULT TO
IMAGINE THE UPR LOW WREAKING HAVOC WITH THE MARINE INVERSION AND
CONSEQUENTLY THE LOW CLOUDS. IF THE MARINE LAYER STAYS AS DEEP AS IT
MORE DRIZZLE WILL ALSO BE POSSIBLE/

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...

19/1130Z

WIDESPREAD STRATUS IN ALL COASTAL AND MOST VLYS AREAS THIS MORNING
SHOULD PUSH INTO REMAINDER OF THE VLYS BY DAYBREAK. CONDS MOSTLY
MVFR...EXCEPT IFR ACROSS SLO/SBA COUNTIES AND IN THE FOOTHILLS
THROUGH MID MORNING. COULD BE SOME DRIZZLE THIS MORNING...MAINLY IN
COASTAL/VLY AREAS OF VTU/L.A. COUNTIES. EXPECT SLOW CLEARING
TODAY...ESPECIALLY NEAR THE COAST...AND CIGS MAY LINGER THRU THE
DAY...ESPECIALLY ON THE S COAST OF SBA COUNTY AND THE VTU COUNTY
COAST. EXPECT AN EARLY RETURN OF LOW CLDS TO MOST AREAS THIS EVENING.

KLAX...MODERATE CONFIDENCE IN THE 12Z TAF. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY. THERE IS
A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS BETWEEN
13Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT BURN OFF UNTIL AT LEAST 20Z.
THERE IS A 20 PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER
06Z ON THE 20TH (TONIGHT)

&&

.MARINE...18/900 PM
WINDS/SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR THE
NEXT FEW DAYS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ACROSS THE
SOUTHERN WATERS WED MORNING THROUGH WED EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...DB
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES










000
FXUS66 KLOX 191045
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
345 AM PDT TUE AUG 19 2014

.SYNOPSIS...

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TODAY-THU)...
2400 FOOT MARINE LAYER WITH LOW CLOUDS ACROSS ALL COASTS AND VLYS
EXCEPT THE SANTA CLARITA AND VENTURA VLYS. THE CLOUDS SHOULD FILL
INTO THESE AREAS BY DAWN. THE LIFTING OF THE MARINE LAYER SHOULD BE
ENOUGH TO PRODUCE SOME DRIZZLE...ESP NEAR THE FOOTHILLS. KDAG
GRADIENT WILL SURGE TO OVER 8 MB THIS AFTERNOON AND THIS WILL MAKE
CLEARING SLOWER THAN NORMAL AND WILL ALSO LIKELY KEEP SOME CLOUDS AT
THE BEACHES. ALL OF THIS LIFT COMES COURTESY OF AN UPPER LOW JUST
WEST OF MONTERREY. BY AFTERNOON THE LOW WILL BE NEAR POINT
CONCEPTION THE COOL POOL OF AIR ALOFT AND A WEAK VORT MAX SHOULD BE
ENOUGH TO CREATE A SLIGHT CHC OF A TSTM OVER THE VTA AND SBA MTNS
THIS AFTERNOON. MAX TEMPS WILL BE BLO NORMAL HAS HGTS FALL THROUGH
THE DAY ALONG WITH THE DEEP MARINE LAYER AND STRONGER THAN NORMAL
ONSHORE FLOW. THIS STRONG ONSHORE FLOW TO KDAG WILL ALSO CREATE NEAR
ADVISORY LEVEL WINDS ACROSS PART OF THE ANTELOPE VLY ESP THE LAKE
PALMDALE AREA.

THE UPPER LOW WILL SIT ATOP OF VENTURA COUNTY. WHAT THE CLOUD FIELD
IS GOING TO LOOK LIKE IS A RATHER TRICKY PROPOSITION. RIGHT NOW HAVE
A DEEP MARINE LAYER WITH A CLOUD PATTER COVERING THE COASTS AND
VLYS. THIS IS THE MOSTLY LIKELY SCENARIO BUT IT IS NOT DIFFICULT TO
IMAGINE THE UPR LOW WREAKING HAVOC WITH THE MARINE INVERSION AND
CONSEQUENTLY THE LOW CLOUDS. IF THE MARINE LAYER STAYS AS DEEP AS IT
MORE DRIZZLE WILL ALSO BE POSSIBLE/

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...

19/0520Z

WIDESPREAD STRATUS ON THE CENTRAL COAST WILL SPREAD INTO THE SANTA
YNEZ AND SALINAS VALLEYS BY MIDNIGHT...WITH WIDESPREAD STRATUS
PUSHING INTO COASTAL SECTIONS OF SRN SBA COUNTY AND VTU COUNTY AS
WELL. EXPECT CONDS TO BE IFR...THEN RISE TO MVFR IN COASTAL SECTIONS
LATE TONIGHT. BURNOFF TIMES SHOULD BE BY MID TO LATE MORNING IN THE
VLYS...AND EARLY AFTERNOON NEAR THE COAST. CLOUDS WILL LIKELY LINGER
THROUGH THE DAY IN SOME COASTAL AREAS...AND RETURN TO THOSE AREAS
THAT CLEAR IN THE EVENING.

ACROSS L.A. COUNTY...THE MARINE INVERSION IS HIGHER...SO EXPECT MVFR
CONDS ACROSS COASTAL SECTIONS BY MIDNIGHT...SPREADING INTO THE VLYS
LATER TONIGHT...WITH MOSTLY IFR CONDS IN THE VLYS. CIGS WILL RISE BY
MORNING...WITH MVFR CONDS ACROSS MOST OF L.A. COUNTY. COULD BE SOME
DRIZZLE AS WELL...ESPECIALLY IN THE VLYS. SLOW BURNOFF EXPECTED ON
TUE...ESPECIALLY NEAR THE COAST. THERE WILL BE AN EARLY RETURN OF
LOW CLOUDS TUE EVENING...AND POSSIBLY BY LATE TUE P.M. NEAR THE
COAST.

KLAX...MODERATE CONFIDENCE IN THE 06Z TAF. THERE IS A 20 PERCENT
CHANCE OF IFR CIGS AT FIRST BETWEEN 07Z AND 10Z. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY TUE. THERE
IS A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS
BETWEEN 10Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 09Z. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER 06Z ON THE 20TH
(TUE NIGHT)

&&

.MARINE...18/900 PM

MODELS SHOW NORTHWEST WINDS AT SMALL CRAFT LEVELS OVER THE OUTER
WATERS FROM WEST OF CAPE SAN MARTIN SOUTHWARD TO SAN NICOLAS ISLAND
THROUGH JUST AFTER MIDNIGHT. WINDS WILL SUBSIDE THROUGH TUESDAY
MORNING AND THEN INCREASE TO 10 TO 20 KNOTS IN THE AFTERNOON AND
PERSIST THROUGH TUESDAY EVENING. WINDS WILL THEN REMAIN MAINLY LIGHT
TO LOCALLY MODERATE THROUGH THE REMAINDER OF THE PERIOD. SEAS WILL
CONSIST OF SHORT PERIOD NORTHWEST SEAS...DIMINISHING AS THE WINDS
SUBSIDE...AND A SMALL SOUTH SWELL.
WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...BRUNO
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES






000
FXUS66 KLOX 191045
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
345 AM PDT TUE AUG 19 2014

.SYNOPSIS...

AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TODAY-THU)...
2400 FOOT MARINE LAYER WITH LOW CLOUDS ACROSS ALL COASTS AND VLYS
EXCEPT THE SANTA CLARITA AND VENTURA VLYS. THE CLOUDS SHOULD FILL
INTO THESE AREAS BY DAWN. THE LIFTING OF THE MARINE LAYER SHOULD BE
ENOUGH TO PRODUCE SOME DRIZZLE...ESP NEAR THE FOOTHILLS. KDAG
GRADIENT WILL SURGE TO OVER 8 MB THIS AFTERNOON AND THIS WILL MAKE
CLEARING SLOWER THAN NORMAL AND WILL ALSO LIKELY KEEP SOME CLOUDS AT
THE BEACHES. ALL OF THIS LIFT COMES COURTESY OF AN UPPER LOW JUST
WEST OF MONTERREY. BY AFTERNOON THE LOW WILL BE NEAR POINT
CONCEPTION THE COOL POOL OF AIR ALOFT AND A WEAK VORT MAX SHOULD BE
ENOUGH TO CREATE A SLIGHT CHC OF A TSTM OVER THE VTA AND SBA MTNS
THIS AFTERNOON. MAX TEMPS WILL BE BLO NORMAL HAS HGTS FALL THROUGH
THE DAY ALONG WITH THE DEEP MARINE LAYER AND STRONGER THAN NORMAL
ONSHORE FLOW. THIS STRONG ONSHORE FLOW TO KDAG WILL ALSO CREATE NEAR
ADVISORY LEVEL WINDS ACROSS PART OF THE ANTELOPE VLY ESP THE LAKE
PALMDALE AREA.

THE UPPER LOW WILL SIT ATOP OF VENTURA COUNTY. WHAT THE CLOUD FIELD
IS GOING TO LOOK LIKE IS A RATHER TRICKY PROPOSITION. RIGHT NOW HAVE
A DEEP MARINE LAYER WITH A CLOUD PATTER COVERING THE COASTS AND
VLYS. THIS IS THE MOSTLY LIKELY SCENARIO BUT IT IS NOT DIFFICULT TO
IMAGINE THE UPR LOW WREAKING HAVOC WITH THE MARINE INVERSION AND
CONSEQUENTLY THE LOW CLOUDS. IF THE MARINE LAYER STAYS AS DEEP AS IT
MORE DRIZZLE WILL ALSO BE POSSIBLE/

THE WEDNESDAY FORECAST IS NOW DIFFERENT FROM YDY. THE NAM SHOWS A
NARROW RIBBON OF MOISTURE WRAPPING AROUND THE LOW AND THEN OVER L.A.
COUNTY ALONG WITH A WEAK LITTLE WAVE. IF ALL OF THIS COMES TOGETHER
AS THE NAM FCSTS IT WOULD PRODUCE A DECENT ENVIRONMENT FOR TSTMS
ANYWHERE OVER LA COUNTY AND THE ADJACENT WATERS. BUT THE GFS AND EC
DO NOT AGREE WITH THIS AGGRESSIVE SOLN SO ONLY MENTION SLIGHT CHC
FOR THE AFFECTED AREA. WILL REALLY HAVE TO KEEP AN EYE ON THINGS.
THE WRAP AROUND MOISTURE CONTINUES AND EXPANDS WEDNESDAY AFTERNOON.
ALL OF LA COUNTY AND THE VTA MTNS WILL SEE A SLIGHT CHC OF SHOWERS
OR TSTMS. AGAIN THE GFS/EC MDLS ARE MUCH LESS OPTIMISTIC FOR
CONVECTION. MAX TEMPS AGAIN WILL BE BLO NORMAL...IN FACT...WEDNESDAY
WILL BE THE COOLEST DAY OF THE NEXT 7 WITH MAX TEMPS 8 TO 12 DEGREES
BLO NORMAL ACROSS MOST AREAS.

THE UPPER LOW EXITS THE AREA TO THE ESE THURSDAY AND THE CONVECTION
THREAT SHOULD END. HGTS RISE AND THE ONSHORE FLOW RELAXES A BIT SO
LOOK FOR A SLIGHT WARMING TREND. THE MARINE LAYER SHOULD REMAIN DEEP
ENOUGH TO ALLOW LOW CLOUDS TO MOVE INTO THE VLYS.

.LONG TERM (FRI-MON)...
HIGH PRESSURE SLOWLY PINCHES IN FROM THE EAST OVER THE LONG TERM AND
KEEPS A PAC NW TROF AND A UPPER LOW WHICH IS SPINNING TO THE SW AT
BAY. RISING HGTS WILL SMOOSH THE MARINE LAYER CLOUDS OUT OF THE VLYS
AND DECREASE THE ONSHORE FLOW. LOOK FOR MAX TEMPS TO RISE SOME EACH
DAY. MAX TEMPS SHOULD BE ABOVE NORMAL BY SUNDAY OR MONDAY.

&&

.AVIATION...

19/0520Z

WIDESPREAD STRATUS ON THE CENTRAL COAST WILL SPREAD INTO THE SANTA
YNEZ AND SALINAS VALLEYS BY MIDNIGHT...WITH WIDESPREAD STRATUS
PUSHING INTO COASTAL SECTIONS OF SRN SBA COUNTY AND VTU COUNTY AS
WELL. EXPECT CONDS TO BE IFR...THEN RISE TO MVFR IN COASTAL SECTIONS
LATE TONIGHT. BURNOFF TIMES SHOULD BE BY MID TO LATE MORNING IN THE
VLYS...AND EARLY AFTERNOON NEAR THE COAST. CLOUDS WILL LIKELY LINGER
THROUGH THE DAY IN SOME COASTAL AREAS...AND RETURN TO THOSE AREAS
THAT CLEAR IN THE EVENING.

ACROSS L.A. COUNTY...THE MARINE INVERSION IS HIGHER...SO EXPECT MVFR
CONDS ACROSS COASTAL SECTIONS BY MIDNIGHT...SPREADING INTO THE VLYS
LATER TONIGHT...WITH MOSTLY IFR CONDS IN THE VLYS. CIGS WILL RISE BY
MORNING...WITH MVFR CONDS ACROSS MOST OF L.A. COUNTY. COULD BE SOME
DRIZZLE AS WELL...ESPECIALLY IN THE VLYS. SLOW BURNOFF EXPECTED ON
TUE...ESPECIALLY NEAR THE COAST. THERE WILL BE AN EARLY RETURN OF
LOW CLOUDS TUE EVENING...AND POSSIBLY BY LATE TUE P.M. NEAR THE
COAST.

KLAX...MODERATE CONFIDENCE IN THE 06Z TAF. THERE IS A 20 PERCENT
CHANCE OF IFR CIGS AT FIRST BETWEEN 07Z AND 10Z. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY TUE. THERE
IS A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS
BETWEEN 10Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 09Z. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER 06Z ON THE 20TH
(TUE NIGHT)

&&

.MARINE...18/900 PM

MODELS SHOW NORTHWEST WINDS AT SMALL CRAFT LEVELS OVER THE OUTER
WATERS FROM WEST OF CAPE SAN MARTIN SOUTHWARD TO SAN NICOLAS ISLAND
THROUGH JUST AFTER MIDNIGHT. WINDS WILL SUBSIDE THROUGH TUESDAY
MORNING AND THEN INCREASE TO 10 TO 20 KNOTS IN THE AFTERNOON AND
PERSIST THROUGH TUESDAY EVENING. WINDS WILL THEN REMAIN MAINLY LIGHT
TO LOCALLY MODERATE THROUGH THE REMAINDER OF THE PERIOD. SEAS WILL
CONSIST OF SHORT PERIOD NORTHWEST SEAS...DIMINISHING AS THE WINDS
SUBSIDE...AND A SMALL SOUTH SWELL.
WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...BRUNO
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES







000
FXUS66 KLOX 190518 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1020 PM PDT MON AUG 18 2014

UPDATED AVIATION SECTION

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TONIGHT-THU)...UPDATE
AS EXPECTED...HIGH TEMPS WERE DOWN A FEW DEGREES ACROSS THE BOARD
THIS AFTERNOON. THIS WAS DUE TO THE COMBINATION OF AN UPPER LOW
DROPPING SOUTH OFF THE COAST OF NORTHERN CALIFORNIA AND SLIGHTLY
STRONGER ONSHORE FLOW WITH A DEEPER MARINE LAYER COMPARED TO
YESTERDAY AFTERNOON. THE LATEST ACARS SOUNDING NEAR LAX INDICATED
THE MARINE LAYER AROUND 1200 FT DEEP WITH A SLIGHTLY WEAKER
INVERSION COMPARED TO YESTERDAY AT THIS TIME. LATEST FOG PRODUCT
IMAGERY SHOWED LOW CLOUDS ALREADY SPREADING WELL INLAND ACROSS THE
CENTRAL COAST AS WELL AS FILLING IN ACROSS THE SO CAL BIGHT THIS
EVENING. CONFIDENCE IS HIGH THAT LOW CLOUDS WILL QUICKLY SPREAD
ACROSS COASTAL AREAS THIS EVENING AND WELL INTO THE VALLEYS THROUGH
THE OVERNIGHT HOURS. THE MARINE LAYER DEPTH COULD REACH AROUND 2000
FT LATE TONIGHT. THERE WILL PATCHY DRIZZLE POSSIBLE JUST ABOUT
ANYWHERE WEST OF THE MOUNTAINS LATE TONIGHT INTO EARLY TUE
MORNING...ESPECIALLY AROUND THE LA/VTU COUNTY VALLEYS NEAR THE
FOOTHILLS DUE TO OROGRAPHIC LIFT. THE INVERSION SHOULD REMAIN
RELATIVELY STRONG...AND WITH A STRONGER ONSHORE FLOW
EXPECTED...VALLEYS COULD REMAIN CLOUDY UNTIL NOONISH WHILE CLEARING
ALONG ALL THE COASTAL PLAIN SHOULD BE TOUGH TO DO. HIGHEST
CONFIDENCE THAT VENTURA AND SANTA BARBARA SOUTH COAST WILL REMAIN
CLOUDY ALL DAY...WITH LA COUNTY COASTAL AREAS SEEING A FEW HOURS OF
CLEARING IN THE LATE AFTERNOON HOURS. THE CENTRAL COAST SHOULD
REMAIN CLOUDY MOST OF THE DAY NEAR THE BEACHES AS WELL. THIS WILL
HAVE A PROFOUND AFFECT ON HIGH TEMPS TOMORROW AS MANY INLAND
LOCATIONS WILL BE 8 TO 12 DEGREES COOLER...AND PASO ROBLES COULD BE
AS MUCH AS 18 DEGREES COOLER WITH A HIGH NEAR 80 DEGREES FROM A 97
REPORTED TODAY.

THE UPPER LOW WILL CONTINUE TO DRIFT SOUTH ALONG THE COAST AS IT
SETS UP AROUND POINT CONCEPTION BY TUE AFTERNOON. ALTHOUGH THERE IS
LITTLE IN THE WAY OF MOISTURE TO TAP INTO...THERE WILL BE ENOUGH
INSTABILITY ACROSS THE SBA/VENTURA COUNTY MTNS SO ADDED A SLIGHT
CHANCE OF SHOWERS OR THUNDERSTORMS. LOOKING AT MODEL SOUNDINGS...IF
ISOLATED STORMS DO DEVELOP THEY WILL BE ELEVATED WITH THE MAIN RISK
BEING GUSTY DOWNDRAFT WINDS AND POSSIBLE DRY LIGHTNING. PRECIPITABLE
WATERS WERE NOT IMPRESSIVE AND MODERATE SW STEERING WINDS WILL KEEP
ANY THUNDERSTORMS FROM PRODUCING ANY FLOOD IMPLICATIONS.

LOW CLOUDS WILL QUICKLY PUSH INLAND ONCE AGAIN TUESDAY EVENING
ACROSS ALL COASTAL AREAS THEN INLAND TO THE COASTAL SLOPES
OVERNIGHT. MORE PATCHY DRIZZLE WILL BE POSSIBLE...ESPECIALLY SOUTH
OF POINT CONCEPTION FOR COAST AND VALLEYS LATE TUE NIGHT INTO WED
MORNING. THE UPPER LOW WILL CONTINUE TO SLOWLY DRIFT OVER LA/VTU
COUNTIES ON WEDNESDAY. THERE WILL CONTINUE TO BE LITTLE MOISTURE TO
WORK WITH...BUT THERE WILL BE MORE INSTABILITY ACROSS THE SBA/VTU
COUNTY MOUNTAINS AS WELL AS THE LA COUNTY MTNS AND EASTERN PORTION
OF THE ANTELOPE VALLEY. ONCE AGAIN...SLIGHT CHANCE FOR SHOWERS OR
THUNDERSTORMS ARE IN THE FORECAST FOR THE AREAS MENTIONED. MAIN
ISSUES WILL BE GUSTY DOWNDRAFT WINDS AS STORMS COLLAPSE AND POSSIBLE
DRY LIGHTNING. HIGH TEMPS ONCE AGAIN WILL REMAIN QUITE COOL FOR THIS
TIME OF YEAR. LOW CLOUDS SHOULD LINGER ONCE AGAIN ACROSS VALLEYS
THEN SCOUR OUT LATE MORNING OR AROUND NOON...WHILE COASTAL AREAS
COULD SEE SOME CLEARING LATE IN THE AFTERNOON.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...19/0520Z.
WIDESPREAD STRATUS ON THE CENTRAL COAST WILL SPREAD INTO THE SANTA
YNEZ AND SALINAS VALLEYS BY MIDNIGHT...WITH WIDESPREAD STRATUS
PUSHING INTO COASTAL SECTIONS OF SRN SBA COUNTY AND VTU COUNTY AS
WELL. EXPECT CONDS TO BE IFR...THEN RISE TO MVFR IN COASTAL SECTIONS
LATE TONIGHT. BURNOFF TIMES SHOULD BE BY MID TO LATE MORNING IN THE
VLYS...AND EARLY AFTERNOON NEAR THE COAST. CLOUDS WILL LIKELY LINGER
THROUGH THE DAY IN SOME COASTAL AREAS...AND RETURN TO THOSE AREAS
THAT CLEAR IN THE EVENING.

ACROSS L.A. COUNTY...THE MARINE INVERSION IS HIGHER...SO EXPECT MVFR
CONDS ACROSS COASTAL SECTIONS BY MIDNIGHT...SPREADING INTO THE VLYS
LATER TONIGHT...WITH MOSTLY IFR CONDS IN THE VLYS. CIGS WILL RISE BY
MORNING...WITH MVFR CONDS ACROSS MOST OF L.A. COUNTY. COULD BE SOME
DRIZZLE AS WELL...ESPECIALLY IN THE VLYS. SLOW BURNOFF EXPECTED ON
TUE...ESPECIALLY NEAR THE COAST. THERE WILL BE AN EARLY RETURN OF
LOW CLOUDS TUE EVENING...AND POSSIBLY BY LATE TUE P.M. NEAR THE
COAST.

KLAX...MODERATE CONFIDENCE IN THE 06Z TAF. THERE IS A 20 PERCENT
CHANCE OF IFR CIGS AT FIRST BETWEEN 07Z AND 10Z. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY TUE. THERE
IS A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS
BETWEEN 10Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 09Z. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER 06Z ON THE 20TH
(TUE NIGHT)

&&

.MARINE...18/900 PM

MODELS SHOW NORTHWEST WINDS AT SMALL CRAFT LEVELS OVER THE OUTER
WATERS FROM WEST OF CAPE SAN MARTIN SOUTHWARD TO SAN NICOLAS ISLAND
THROUGH JUST AFTER MIDNIGHT. WINDS WILL SUBSIDE THROUGH TUESDAY
MORNING AND THEN INCREASE TO 10 TO 20 KNOTS IN THE AFTERNOON AND
PERSIST THROUGH TUESDAY EVENING. WINDS WILL THEN REMAIN MAINLY LIGHT
TO LOCALLY MODERATE THROUGH THE REMAINDER OF THE PERIOD. SEAS WILL
CONSIST OF SHORT PERIOD NORTHWEST SEAS...DIMINISHING AS THE WINDS
SUBSIDE...AND A SMALL SOUTH SWELL.
WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/BOLDT
AVIATION...DB
MARINE...SMITH
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES



















000
FXUS66 KLOX 190518 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1020 PM PDT MON AUG 18 2014

UPDATED AVIATION SECTION

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TONIGHT-THU)...UPDATE
AS EXPECTED...HIGH TEMPS WERE DOWN A FEW DEGREES ACROSS THE BOARD
THIS AFTERNOON. THIS WAS DUE TO THE COMBINATION OF AN UPPER LOW
DROPPING SOUTH OFF THE COAST OF NORTHERN CALIFORNIA AND SLIGHTLY
STRONGER ONSHORE FLOW WITH A DEEPER MARINE LAYER COMPARED TO
YESTERDAY AFTERNOON. THE LATEST ACARS SOUNDING NEAR LAX INDICATED
THE MARINE LAYER AROUND 1200 FT DEEP WITH A SLIGHTLY WEAKER
INVERSION COMPARED TO YESTERDAY AT THIS TIME. LATEST FOG PRODUCT
IMAGERY SHOWED LOW CLOUDS ALREADY SPREADING WELL INLAND ACROSS THE
CENTRAL COAST AS WELL AS FILLING IN ACROSS THE SO CAL BIGHT THIS
EVENING. CONFIDENCE IS HIGH THAT LOW CLOUDS WILL QUICKLY SPREAD
ACROSS COASTAL AREAS THIS EVENING AND WELL INTO THE VALLEYS THROUGH
THE OVERNIGHT HOURS. THE MARINE LAYER DEPTH COULD REACH AROUND 2000
FT LATE TONIGHT. THERE WILL PATCHY DRIZZLE POSSIBLE JUST ABOUT
ANYWHERE WEST OF THE MOUNTAINS LATE TONIGHT INTO EARLY TUE
MORNING...ESPECIALLY AROUND THE LA/VTU COUNTY VALLEYS NEAR THE
FOOTHILLS DUE TO OROGRAPHIC LIFT. THE INVERSION SHOULD REMAIN
RELATIVELY STRONG...AND WITH A STRONGER ONSHORE FLOW
EXPECTED...VALLEYS COULD REMAIN CLOUDY UNTIL NOONISH WHILE CLEARING
ALONG ALL THE COASTAL PLAIN SHOULD BE TOUGH TO DO. HIGHEST
CONFIDENCE THAT VENTURA AND SANTA BARBARA SOUTH COAST WILL REMAIN
CLOUDY ALL DAY...WITH LA COUNTY COASTAL AREAS SEEING A FEW HOURS OF
CLEARING IN THE LATE AFTERNOON HOURS. THE CENTRAL COAST SHOULD
REMAIN CLOUDY MOST OF THE DAY NEAR THE BEACHES AS WELL. THIS WILL
HAVE A PROFOUND AFFECT ON HIGH TEMPS TOMORROW AS MANY INLAND
LOCATIONS WILL BE 8 TO 12 DEGREES COOLER...AND PASO ROBLES COULD BE
AS MUCH AS 18 DEGREES COOLER WITH A HIGH NEAR 80 DEGREES FROM A 97
REPORTED TODAY.

THE UPPER LOW WILL CONTINUE TO DRIFT SOUTH ALONG THE COAST AS IT
SETS UP AROUND POINT CONCEPTION BY TUE AFTERNOON. ALTHOUGH THERE IS
LITTLE IN THE WAY OF MOISTURE TO TAP INTO...THERE WILL BE ENOUGH
INSTABILITY ACROSS THE SBA/VENTURA COUNTY MTNS SO ADDED A SLIGHT
CHANCE OF SHOWERS OR THUNDERSTORMS. LOOKING AT MODEL SOUNDINGS...IF
ISOLATED STORMS DO DEVELOP THEY WILL BE ELEVATED WITH THE MAIN RISK
BEING GUSTY DOWNDRAFT WINDS AND POSSIBLE DRY LIGHTNING. PRECIPITABLE
WATERS WERE NOT IMPRESSIVE AND MODERATE SW STEERING WINDS WILL KEEP
ANY THUNDERSTORMS FROM PRODUCING ANY FLOOD IMPLICATIONS.

LOW CLOUDS WILL QUICKLY PUSH INLAND ONCE AGAIN TUESDAY EVENING
ACROSS ALL COASTAL AREAS THEN INLAND TO THE COASTAL SLOPES
OVERNIGHT. MORE PATCHY DRIZZLE WILL BE POSSIBLE...ESPECIALLY SOUTH
OF POINT CONCEPTION FOR COAST AND VALLEYS LATE TUE NIGHT INTO WED
MORNING. THE UPPER LOW WILL CONTINUE TO SLOWLY DRIFT OVER LA/VTU
COUNTIES ON WEDNESDAY. THERE WILL CONTINUE TO BE LITTLE MOISTURE TO
WORK WITH...BUT THERE WILL BE MORE INSTABILITY ACROSS THE SBA/VTU
COUNTY MOUNTAINS AS WELL AS THE LA COUNTY MTNS AND EASTERN PORTION
OF THE ANTELOPE VALLEY. ONCE AGAIN...SLIGHT CHANCE FOR SHOWERS OR
THUNDERSTORMS ARE IN THE FORECAST FOR THE AREAS MENTIONED. MAIN
ISSUES WILL BE GUSTY DOWNDRAFT WINDS AS STORMS COLLAPSE AND POSSIBLE
DRY LIGHTNING. HIGH TEMPS ONCE AGAIN WILL REMAIN QUITE COOL FOR THIS
TIME OF YEAR. LOW CLOUDS SHOULD LINGER ONCE AGAIN ACROSS VALLEYS
THEN SCOUR OUT LATE MORNING OR AROUND NOON...WHILE COASTAL AREAS
COULD SEE SOME CLEARING LATE IN THE AFTERNOON.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...19/0520Z.
WIDESPREAD STRATUS ON THE CENTRAL COAST WILL SPREAD INTO THE SANTA
YNEZ AND SALINAS VALLEYS BY MIDNIGHT...WITH WIDESPREAD STRATUS
PUSHING INTO COASTAL SECTIONS OF SRN SBA COUNTY AND VTU COUNTY AS
WELL. EXPECT CONDS TO BE IFR...THEN RISE TO MVFR IN COASTAL SECTIONS
LATE TONIGHT. BURNOFF TIMES SHOULD BE BY MID TO LATE MORNING IN THE
VLYS...AND EARLY AFTERNOON NEAR THE COAST. CLOUDS WILL LIKELY LINGER
THROUGH THE DAY IN SOME COASTAL AREAS...AND RETURN TO THOSE AREAS
THAT CLEAR IN THE EVENING.

ACROSS L.A. COUNTY...THE MARINE INVERSION IS HIGHER...SO EXPECT MVFR
CONDS ACROSS COASTAL SECTIONS BY MIDNIGHT...SPREADING INTO THE VLYS
LATER TONIGHT...WITH MOSTLY IFR CONDS IN THE VLYS. CIGS WILL RISE BY
MORNING...WITH MVFR CONDS ACROSS MOST OF L.A. COUNTY. COULD BE SOME
DRIZZLE AS WELL...ESPECIALLY IN THE VLYS. SLOW BURNOFF EXPECTED ON
TUE...ESPECIALLY NEAR THE COAST. THERE WILL BE AN EARLY RETURN OF
LOW CLOUDS TUE EVENING...AND POSSIBLY BY LATE TUE P.M. NEAR THE
COAST.

KLAX...MODERATE CONFIDENCE IN THE 06Z TAF. THERE IS A 20 PERCENT
CHANCE OF IFR CIGS AT FIRST BETWEEN 07Z AND 10Z. THERE IS A 20 TO 30
PERCENT CHANCE THAT MVFR CIGS WILL LINGER THROUGH THE DAY TUE. THERE
IS A 20 PERCENT CHANCE THAT E TO SE WINDS WILL REACH 10 KNOTS
BETWEEN 10Z AND 16Z.

KBUR...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 09Z. THERE IS A 20
PERCENT CHANCE THAT CIGS WILL NOT ARRIVE UNTIL AFTER 06Z ON THE 20TH
(TUE NIGHT)

&&

.MARINE...18/900 PM

MODELS SHOW NORTHWEST WINDS AT SMALL CRAFT LEVELS OVER THE OUTER
WATERS FROM WEST OF CAPE SAN MARTIN SOUTHWARD TO SAN NICOLAS ISLAND
THROUGH JUST AFTER MIDNIGHT. WINDS WILL SUBSIDE THROUGH TUESDAY
MORNING AND THEN INCREASE TO 10 TO 20 KNOTS IN THE AFTERNOON AND
PERSIST THROUGH TUESDAY EVENING. WINDS WILL THEN REMAIN MAINLY LIGHT
TO LOCALLY MODERATE THROUGH THE REMAINDER OF THE PERIOD. SEAS WILL
CONSIST OF SHORT PERIOD NORTHWEST SEAS...DIMINISHING AS THE WINDS
SUBSIDE...AND A SMALL SOUTH SWELL.
WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/BOLDT
AVIATION...DB
MARINE...SMITH
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES


















000
FXUS66 KLOX 190325
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
825 PM PDT MON AUG 18 2014

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TONIGHT-THU)...UPDATE
AS EXPECTED...HIGH TEMPS WERE DOWN A FEW DEGREES ACROSS THE BOARD
THIS AFTERNOON. THIS WAS DUE TO THE COMBINATION OF AN UPPER LOW
DROPPING SOUTH OFF THE COAST OF NORTHERN CALIFORNIA AND SLIGHTLY
STRONGER ONSHORE FLOW WITH A DEEPER MARINE LAYER COMPARED TO
YESTERDAY AFTERNOON. THE LATEST ACARS SOUNDING NEAR LAX INDICATED
THE MARINE LAYER AROUND 1200 FT DEEP WITH A SLIGHTLY WEAKER
INVERSION COMPARED TO YESTERDAY AT THIS TIME. LATEST FOG PRODUCT
IMAGERY SHOWED LOW CLOUDS ALREADY SPREADING WELL INLAND ACROSS THE
CENTRAL COAST AS WELL AS FILLING IN ACROSS THE SO CAL BIGHT THIS
EVENING. CONFIDENCE IS HIGH THAT LOW CLOUDS WILL QUICKLY SPREAD
ACROSS COASTAL AREAS THIS EVENING AND WELL INTO THE VALLEYS THROUGH
THE OVERNIGHT HOURS. THE MARINE LAYER DEPTH COULD REACH AROUND 2000
FT LATE TONIGHT. THERE WILL PATCHY DRIZZLE POSSIBLE JUST ABOUT
ANYWHERE WEST OF THE MOUNTAINS LATE TONIGHT INTO EARLY TUE
MORNING...ESPECIALLY AROUND THE LA/VTU COUNTY VALLEYS NEAR THE
FOOTHILLS DUE TO OROGRAPHIC LIFT. THE INVERSION SHOULD REMAIN
RELATIVELY STRONG...AND WITH A STRONGER ONSHORE FLOW
EXPECTED...VALLEYS COULD REMAIN CLOUDY UNTIL NOONISH WHILE CLEARING
ALONG ALL THE COASTAL PLAIN SHOULD BE TOUGH TO DO. HIGHEST
CONFIDENCE THAT VENTURA AND SANTA BARBARA SOUTH COAST WILL REMAIN
CLOUDY ALL DAY...WITH LA COUNTY COASTAL AREAS SEEING A FEW HOURS OF
CLEARING IN THE LATE AFTERNOON HOURS. THE CENTRAL COAST SHOULD
REMAIN CLOUDY MOST OF THE DAY NEAR THE BEACHES AS WELL. THIS WILL
HAVE A PROFOUND AFFECT ON HIGH TEMPS TOMORROW AS MANY INLAND
LOCATIONS WILL BE 8 TO 12 DEGREES COOLER...AND PASO ROBLES COULD BE
AS MUCH AS 18 DEGREES COOLER WITH A HIGH NEAR 80 DEGREES FROM A 97
REPORTED TODAY.

THE UPPER LOW WILL CONTINUE TO DRIFT SOUTH ALONG THE COAST AS IT
SETS UP AROUND POINT CONCEPTION BY TUE AFTERNOON. ALTHOUGH THERE IS
LITTLE IN THE WAY OF MOISTURE TO TAP INTO...THERE WILL BE ENOUGH
INSTABILITY ACROSS THE SBA/VENTURA COUNTY MTNS SO ADDED A SLIGHT
CHANCE OF SHOWERS OR THUNDERSTORMS. LOOKING AT MODEL SOUNDINGS...IF
ISOLATED STORMS DO DEVELOP THEY WILL BE ELEVATED WITH THE MAIN RISK
BEING GUSTY DOWNDRAFT WINDS AND POSSIBLE DRY LIGHTNING. PRECIPITABLE
WATERS WERE NOT IMPRESSIVE AND MODERATE SW STEERING WINDS WILL KEEP
ANY THUNDERSTORMS FROM PRODUCING ANY FLOOD IMPLICATIONS.

LOW CLOUDS WILL QUICKLY PUSH INLAND ONCE AGAIN TUESDAY EVENING
ACROSS ALL COASTAL AREAS THEN INLAND TO THE COASTAL SLOPES
OVERNIGHT. MORE PATCHY DRIZZLE WILL BE POSSIBLE...ESPECIALLY SOUTH
OF POINT CONCEPTION FOR COAST AND VALLEYS LATE TUE NIGHT INTO WED
MORNING. THE UPPER LOW WILL CONTINUE TO SLOWLY DRIFT OVER LA/VTU
COUNTIES ON WEDNESDAY. THERE WILL CONTINUE TO BE LITTLE MOISTURE TO
WORK WITH...BUT THERE WILL BE MORE INSTABILITY ACROSS THE SBA/VTU
COUNTY MOUNTAINS AS WELL AS THE LA COUNTY MTNS AND EASTERN PORTION
OF THE ANTELOPE VALLEY. ONCE AGAIN...SLIGHT CHANCE FOR SHOWERS OR
THUNDERSTORMS ARE IN THE FORECAST FOR THE AREAS MENTIONED. MAIN
ISSUES WILL BE GUSTY DOWNDRAFT WINDS AS STORMS COLLAPSE AND POSSIBLE
DRY LIGHTNING. HIGH TEMPS ONCE AGAIN WILL REMAIN QUITE COOL FOR THIS
TIME OF YEAR. LOW CLOUDS SHOULD LINGER ONCE AGAIN ACROSS VALLEYS
THEN SCOUR OUT LATE MORNING OR AROUND NOON...WHILE COASTAL AREAS
COULD SEE SOME CLEARING LATE IN THE AFTERNOON.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...19/0045Z.

LATEST ACARS SOUNDING NEAR KLAX WAS AROUND 1200 FT. THIS IS IN LINE
WITH THINKING THAT MARINE LAYER INVERSION WILL DEEPEN OVERNIGHT
ALLOWING FLOW STRATUS TO REACH VALLEY AREAS OVERNIGHT. MARINE LAYER
SHOULD REACH AT LEAST 1500 FT...POSSIBLY HIGHER BY EARLY TUE MORNING.

N OF POINT CONCEPTION...MODERATE CONFIDENCE WITH 00Z TAFS. EXPECT
HIGH IFR CIGS TONIGHT EXCEPT MVFR AT KSBP AFTER 11Z. 50 PERCENT
CHANCE FOR MVFR CIGS FOR KSMX AFTER 12Z. 30 PERCENT CHANCE THAT CIGS
WILL NOT SCOUR OUT ALL DAY. CONTINUE WITH MODERATE TO HIGH
CONFIDENCE FOR IFR/MVFR CIGS TO PUSH INLAND EARLY TUE EVENING ONCE
AGAIN. HIGH CONFIDENCE FOR KPRB TO HAVE HIGH IFR CIGS AFTER 10Z
TONIGHT. LOWER CONFIDENCE WITH SCOUR OUT TIME. +/- 2 HOURS FROM 00Z
TAF.

S OF POINT CONCEPTION...MODERATE CONFIDENCE WITH IFR/MVFR CIGS TO
INITIATE ACROSS LA/VTU/SBA COUNTIES BETWEEN 05-08Z. IFR CIGS WILL
BECOME MVFR FOR MOST ALL COASTAL AREAS BY 14Z FOR KOXR/KSBA AND
REMAIN ABOVE MVFR CONDS FOR KLAX AND KLGB. HIGHER CONFIDENCE THAT
KBUR AND KVNY WILL EXPERIENCE IFR/ TO LOW MVFR CIGS BY 10Z TONIGHT.
GIVE OR TAKE AN HOUR. LOW CLOUDS SHOULD SCOUR OUT WITHIN A COUPLE
HOURS OF 19Z. 20 PERCENT CHANCE THAT CIGS COULD LINGER THROUGH 22Z.
GOOD CHANCE THAT MVFR CIGS WILL SEE ONLY AN HOUR OR TWO OF AFTERNOON
CLEARING ALONG THE VENTURA/SBA COASTAL AREAS. 40 PERCENT CHANCE FOR
CIGS TO REMAIN THE ENTIRE AFTERNOON. EXCEPT EARLIER CLEARING FOR LA
COUNTY COASTAL AREAS.

KLAX...MODERATE CONFIDENCE FOR MVFR CIGS FROM LATE THIS EVENING
THROUGH MOST OF TUESDAY. 40 PERCENT CHANCE THAT MVFR CIGS COULD
LINGER A FEW HOURS PAST 21Z. LOW CLOUDS SHOULD BE QUICK TO RE
ESTABLISH TUE EVENING AND A SIMILAR LOW CLOUD REGIME SHOULD OCCUR
TUE EVE INTO WED. THERE IS A 40 PERCENT CHANCE OF -DZ BETWEEN
10Z-15Z.

KBUR...MODERATE CONFIDENCE FOR IFR CONDS AFTER 09Z WITH 50 PERCENT
CHANCE FOR -DZ BETWEEN 09Z AND 16Z. 30 PERCENT CHANCE FOR CIGS TO
SCOUR OUT 2 HOURS AFTER 19Z. LOW CLOUDS SHOULD REDEVELOP ONCE AGAIN
TUE LATE EVEN OR AFTER MIDNIGHT WITH SIMILAR BURNOFF TIMES AND
POSSIBLE DRIZZLE ONCE AGAIN.

&&

.MARINE...18/900 PM

MODELS SHOW NORTHWEST WINDS AT SMALL CRAFT LEVELS OVER THE OUTER
WATERS FROM WEST OF CAPE SAN MARTIN SOUTHWARD TO SAN NICOLAS ISLAND
THROUGH JUST AFTER MIDNIGHT. WINDS WILL SUBSIDE THROUGH TUESDAY
MORNING AND THEN INCREASE TO 10 TO 20 KNOTS IN THE AFTERNOON AND
PERSIST THROUGH TUESDAY EVENING. WINDS WILL THEN REMAIN MAINLY LIGHT
TO LOCALLY MODERATE THROUGH THE REMAINDER OF THE PERIOD. SEAS WILL
CONSIST OF SHORT PERIOD NORTHWEST SEAS...DIMINISHING AS THE WINDS
SUBSIDE...AND A SMALL SOUTH SWELL.
WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/BOLDT
AVIATION...KAPLAN
MARINE...SMITH
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES















000
FXUS66 KLOX 190325
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
825 PM PDT MON AUG 18 2014

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY. EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE WITH ISOLATED MOUNTAIN SHOWERS OR
THUNDERSTORMS. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE
IN LATER IN THE WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON
THUNDERSTORMS IN THE MOUNTAINS.

&&

.SHORT TERM (TONIGHT-THU)...UPDATE
AS EXPECTED...HIGH TEMPS WERE DOWN A FEW DEGREES ACROSS THE BOARD
THIS AFTERNOON. THIS WAS DUE TO THE COMBINATION OF AN UPPER LOW
DROPPING SOUTH OFF THE COAST OF NORTHERN CALIFORNIA AND SLIGHTLY
STRONGER ONSHORE FLOW WITH A DEEPER MARINE LAYER COMPARED TO
YESTERDAY AFTERNOON. THE LATEST ACARS SOUNDING NEAR LAX INDICATED
THE MARINE LAYER AROUND 1200 FT DEEP WITH A SLIGHTLY WEAKER
INVERSION COMPARED TO YESTERDAY AT THIS TIME. LATEST FOG PRODUCT
IMAGERY SHOWED LOW CLOUDS ALREADY SPREADING WELL INLAND ACROSS THE
CENTRAL COAST AS WELL AS FILLING IN ACROSS THE SO CAL BIGHT THIS
EVENING. CONFIDENCE IS HIGH THAT LOW CLOUDS WILL QUICKLY SPREAD
ACROSS COASTAL AREAS THIS EVENING AND WELL INTO THE VALLEYS THROUGH
THE OVERNIGHT HOURS. THE MARINE LAYER DEPTH COULD REACH AROUND 2000
FT LATE TONIGHT. THERE WILL PATCHY DRIZZLE POSSIBLE JUST ABOUT
ANYWHERE WEST OF THE MOUNTAINS LATE TONIGHT INTO EARLY TUE
MORNING...ESPECIALLY AROUND THE LA/VTU COUNTY VALLEYS NEAR THE
FOOTHILLS DUE TO OROGRAPHIC LIFT. THE INVERSION SHOULD REMAIN
RELATIVELY STRONG...AND WITH A STRONGER ONSHORE FLOW
EXPECTED...VALLEYS COULD REMAIN CLOUDY UNTIL NOONISH WHILE CLEARING
ALONG ALL THE COASTAL PLAIN SHOULD BE TOUGH TO DO. HIGHEST
CONFIDENCE THAT VENTURA AND SANTA BARBARA SOUTH COAST WILL REMAIN
CLOUDY ALL DAY...WITH LA COUNTY COASTAL AREAS SEEING A FEW HOURS OF
CLEARING IN THE LATE AFTERNOON HOURS. THE CENTRAL COAST SHOULD
REMAIN CLOUDY MOST OF THE DAY NEAR THE BEACHES AS WELL. THIS WILL
HAVE A PROFOUND AFFECT ON HIGH TEMPS TOMORROW AS MANY INLAND
LOCATIONS WILL BE 8 TO 12 DEGREES COOLER...AND PASO ROBLES COULD BE
AS MUCH AS 18 DEGREES COOLER WITH A HIGH NEAR 80 DEGREES FROM A 97
REPORTED TODAY.

THE UPPER LOW WILL CONTINUE TO DRIFT SOUTH ALONG THE COAST AS IT
SETS UP AROUND POINT CONCEPTION BY TUE AFTERNOON. ALTHOUGH THERE IS
LITTLE IN THE WAY OF MOISTURE TO TAP INTO...THERE WILL BE ENOUGH
INSTABILITY ACROSS THE SBA/VENTURA COUNTY MTNS SO ADDED A SLIGHT
CHANCE OF SHOWERS OR THUNDERSTORMS. LOOKING AT MODEL SOUNDINGS...IF
ISOLATED STORMS DO DEVELOP THEY WILL BE ELEVATED WITH THE MAIN RISK
BEING GUSTY DOWNDRAFT WINDS AND POSSIBLE DRY LIGHTNING. PRECIPITABLE
WATERS WERE NOT IMPRESSIVE AND MODERATE SW STEERING WINDS WILL KEEP
ANY THUNDERSTORMS FROM PRODUCING ANY FLOOD IMPLICATIONS.

LOW CLOUDS WILL QUICKLY PUSH INLAND ONCE AGAIN TUESDAY EVENING
ACROSS ALL COASTAL AREAS THEN INLAND TO THE COASTAL SLOPES
OVERNIGHT. MORE PATCHY DRIZZLE WILL BE POSSIBLE...ESPECIALLY SOUTH
OF POINT CONCEPTION FOR COAST AND VALLEYS LATE TUE NIGHT INTO WED
MORNING. THE UPPER LOW WILL CONTINUE TO SLOWLY DRIFT OVER LA/VTU
COUNTIES ON WEDNESDAY. THERE WILL CONTINUE TO BE LITTLE MOISTURE TO
WORK WITH...BUT THERE WILL BE MORE INSTABILITY ACROSS THE SBA/VTU
COUNTY MOUNTAINS AS WELL AS THE LA COUNTY MTNS AND EASTERN PORTION
OF THE ANTELOPE VALLEY. ONCE AGAIN...SLIGHT CHANCE FOR SHOWERS OR
THUNDERSTORMS ARE IN THE FORECAST FOR THE AREAS MENTIONED. MAIN
ISSUES WILL BE GUSTY DOWNDRAFT WINDS AS STORMS COLLAPSE AND POSSIBLE
DRY LIGHTNING. HIGH TEMPS ONCE AGAIN WILL REMAIN QUITE COOL FOR THIS
TIME OF YEAR. LOW CLOUDS SHOULD LINGER ONCE AGAIN ACROSS VALLEYS
THEN SCOUR OUT LATE MORNING OR AROUND NOON...WHILE COASTAL AREAS
COULD SEE SOME CLEARING LATE IN THE AFTERNOON.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...19/0045Z.

LATEST ACARS SOUNDING NEAR KLAX WAS AROUND 1200 FT. THIS IS IN LINE
WITH THINKING THAT MARINE LAYER INVERSION WILL DEEPEN OVERNIGHT
ALLOWING FLOW STRATUS TO REACH VALLEY AREAS OVERNIGHT. MARINE LAYER
SHOULD REACH AT LEAST 1500 FT...POSSIBLY HIGHER BY EARLY TUE MORNING.

N OF POINT CONCEPTION...MODERATE CONFIDENCE WITH 00Z TAFS. EXPECT
HIGH IFR CIGS TONIGHT EXCEPT MVFR AT KSBP AFTER 11Z. 50 PERCENT
CHANCE FOR MVFR CIGS FOR KSMX AFTER 12Z. 30 PERCENT CHANCE THAT CIGS
WILL NOT SCOUR OUT ALL DAY. CONTINUE WITH MODERATE TO HIGH
CONFIDENCE FOR IFR/MVFR CIGS TO PUSH INLAND EARLY TUE EVENING ONCE
AGAIN. HIGH CONFIDENCE FOR KPRB TO HAVE HIGH IFR CIGS AFTER 10Z
TONIGHT. LOWER CONFIDENCE WITH SCOUR OUT TIME. +/- 2 HOURS FROM 00Z
TAF.

S OF POINT CONCEPTION...MODERATE CONFIDENCE WITH IFR/MVFR CIGS TO
INITIATE ACROSS LA/VTU/SBA COUNTIES BETWEEN 05-08Z. IFR CIGS WILL
BECOME MVFR FOR MOST ALL COASTAL AREAS BY 14Z FOR KOXR/KSBA AND
REMAIN ABOVE MVFR CONDS FOR KLAX AND KLGB. HIGHER CONFIDENCE THAT
KBUR AND KVNY WILL EXPERIENCE IFR/ TO LOW MVFR CIGS BY 10Z TONIGHT.
GIVE OR TAKE AN HOUR. LOW CLOUDS SHOULD SCOUR OUT WITHIN A COUPLE
HOURS OF 19Z. 20 PERCENT CHANCE THAT CIGS COULD LINGER THROUGH 22Z.
GOOD CHANCE THAT MVFR CIGS WILL SEE ONLY AN HOUR OR TWO OF AFTERNOON
CLEARING ALONG THE VENTURA/SBA COASTAL AREAS. 40 PERCENT CHANCE FOR
CIGS TO REMAIN THE ENTIRE AFTERNOON. EXCEPT EARLIER CLEARING FOR LA
COUNTY COASTAL AREAS.

KLAX...MODERATE CONFIDENCE FOR MVFR CIGS FROM LATE THIS EVENING
THROUGH MOST OF TUESDAY. 40 PERCENT CHANCE THAT MVFR CIGS COULD
LINGER A FEW HOURS PAST 21Z. LOW CLOUDS SHOULD BE QUICK TO RE
ESTABLISH TUE EVENING AND A SIMILAR LOW CLOUD REGIME SHOULD OCCUR
TUE EVE INTO WED. THERE IS A 40 PERCENT CHANCE OF -DZ BETWEEN
10Z-15Z.

KBUR...MODERATE CONFIDENCE FOR IFR CONDS AFTER 09Z WITH 50 PERCENT
CHANCE FOR -DZ BETWEEN 09Z AND 16Z. 30 PERCENT CHANCE FOR CIGS TO
SCOUR OUT 2 HOURS AFTER 19Z. LOW CLOUDS SHOULD REDEVELOP ONCE AGAIN
TUE LATE EVEN OR AFTER MIDNIGHT WITH SIMILAR BURNOFF TIMES AND
POSSIBLE DRIZZLE ONCE AGAIN.

&&

.MARINE...18/900 PM

MODELS SHOW NORTHWEST WINDS AT SMALL CRAFT LEVELS OVER THE OUTER
WATERS FROM WEST OF CAPE SAN MARTIN SOUTHWARD TO SAN NICOLAS ISLAND
THROUGH JUST AFTER MIDNIGHT. WINDS WILL SUBSIDE THROUGH TUESDAY
MORNING AND THEN INCREASE TO 10 TO 20 KNOTS IN THE AFTERNOON AND
PERSIST THROUGH TUESDAY EVENING. WINDS WILL THEN REMAIN MAINLY LIGHT
TO LOCALLY MODERATE THROUGH THE REMAINDER OF THE PERIOD. SEAS WILL
CONSIST OF SHORT PERIOD NORTHWEST SEAS...DIMINISHING AS THE WINDS
SUBSIDE...AND A SMALL SOUTH SWELL.
WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/BOLDT
AVIATION...KAPLAN
MARINE...SMITH
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES
















000
FXUS66 KLOX 190044
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
545 PM PDT MON AUG 18 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY.  EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE OR ISOLATED SHOWERS.  IT IS
POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE IN LATER IN THE
WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS IN THE
MOUNTAINS.
&&

.SHORT TERM (TONIGHT-THU)...
MAIN FORECAST ISSUES WILL BE DEPTH OF THE MARINE LAYER THE NEXT FEW
DAYS AS WELL AS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS
WED-THU.

UPPER LOW PRESSURE SYSTEM NEAR CRESCENT CITY WILL DROP SOUTHWARD TO
OUR CENTRAL COAST BY TUESDAY AFTERNOON. CURRENTLY OBSERVING A WEAK
JET SPEED MAX ACROSS CENTRAL CALI WHICH IS ENHANCING CIRRUS CLOUDS
IN THAT REGION. CONVECTION WAS STARTING TO FORM NEAR MT SHASTA IN
FAR NORTHERN SECTIONS OF CA EAST OF THE LOW.

TODAY SOUTHWEST CA IS EXPERIENCING A MOSTLY SUNNY DAY WITH HIGH
TEMPERATURES NEAR OR SLIGHTLY BELOW YESTERDAY OVERALL. LOW CLOUDS
ARE HANGING ALONG THE COAST NORTH OF PT CONCEPTION. AS THE LOW DROPS
SOUTHWARD THE MARINE LAYER WILL THICKEN AND ONSHORE PRESSURE
GRADIENTS INCREASE. EXPECT MORE WIDESPREAD STRATUS UP AND DOWN THE
COAST LATE TONIGHT AND PUSHING INTO VALLEYS BY MORNING. WEAK LIFT
COULD RESULT IN PATCHY DRIZZLE AS WELL. MOISTURE LOOKS VERY LIMITED
FOR ANY CONVECTIVE THREAT ON TUESDAY...HOWEVER DID ADD SOME
AFTERNOON CLOUDS TO THE VENTURA COUNTY MOUNTAINS.

COMPUTER MODELS THEN TREAT THE LOW PRESSURE CENTER DIFFERENTLY GOING
INTO WEDNESDAY. THE WRF AND GEM HAVE THE MOST SOUTHERLY TRACK WHILE
THE ECMWF AND GFS KEEP IT MORE INLAND ON WEDNESDAY. THEN ALL MODELS
EXCEPT THE GFS SHIFT THE LOW SOUTHWARD OFF THE SOUTHWEST CA COAST BY
THURSDAY. MARINE LAYER WILL BE DEEPEST ON WEDNESDAY AND HAVE ADDED
PATCHY DRIZZLE IN THE MORNING. SLIGHT INSTABILITY AND MARGINAL
MOISTURE ENOUGH TO CONTINUE IDEA OF SLIGHT CHANCE OF THUNDERSTORMS
ACROSS THE MOUNTAINS ON WEDNESDAY AND ADDED TO THE EASTERN SAN
GABRIEL MOUNTAINS FOR THURSDAY. TEMPERATURES REMAIN COOLER THAN
NORMAL THROUGH WEDNESDAY THEN START TO TURN AROUND ON THURSDAY.

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...19/0045Z.

LATEST ACARS SOUNDING NEAR KLAX WAS AROUND 1200 FT. THIS IS IN LINE
WITH THINKING THAT MARINE LAYER INVERSION WILL DEEPEN OVERNIGHT
ALLOWING FLOW STRATUS TO REACH VALLEY AREAS OVERNIGHT. MARINE LAYER
SHOULD REACH AT LEAST 1500 FT...POSSIBLY HIGHER BY EARLY TUE MORNING.

N OF POINT CONCEPTION...MODERATE CONFIDENCE WITH 00Z TAFS. EXPECT
HIGH IFR CIGS TONIGHT EXCEPT MVFR AT KSBP AFTER 11Z. 50 PERCENT
CHANCE FOR MVFR CIGS FOR KSMX AFTER 12Z. 30 PERCENT CHANCE THAT CIGS
WILL NOT SCOUR OUT ALL DAY. CONTINUE WITH MODERATE TO HIGH
CONFIDENCE FOR IFR/MVFR CIGS TO PUSH INLAND EARLY TUE EVENING ONCE
AGAIN. HIGH CONFIDENCE FOR KPRB TO HAVE HIGH IFR CIGS AFTER 10Z
TONIGHT. LOWER CONFIDENCE WITH SCOUR OUT TIME. +/- 2 HOURS FROM 00Z
TAF.

S OF POINT CONCEPTION...MODERATE CONFIDENCE WITH IFR/MVFR CIGS TO
INITIATE ACROSS LA/VTU/SBA COUNTIES BETWEEN 05-08Z. IFR CIGS WILL
BECOME MVFR FOR MOST ALL COASTAL AREAS BY 14Z FOR KOXR/KSBA AND
REMAIN ABOVE MVFR CONDS FOR KLAX AND KLGB. HIGHER CONFIDENCE THAT
KBUR AND KVNY WILL EXPERIENCE IFR/ TO LOW MVFR CIGS BY 10Z TONIGHT.
GIVE OR TAKE AN HOUR. LOW CLOUDS SHOULD SCOUR OUT WITHIN A COUPLE
HOURS OF 19Z. 20 PERCENT CHANCE THAT CIGS COULD LINGER THROUGH 22Z.
GOOD CHANCE THAT MVFR CIGS WILL SEE ONLY AN HOUR OR TWO OF AFTERNOON
CLEARING ALONG THE VENTURA/SBA COASTAL AREAS. 40 PERCENT CHANCE FOR
CIGS TO REMAIN THE ENTIRE AFTERNOON. EXCEPT EARLIER CLEARING FOR LA
COUNTY COASTAL AREAS.

KLAX...MODERATE CONFIDENCE FOR MVFR CIGS FROM LATE THIS EVENING
THROUGH MOST OF TUESDAY. 40 PERCENT CHANCE THAT MVFR CIGS COULD
LINGER A FEW HOURS PAST 21Z. LOW CLOUDS SHOULD BE QUICK TO RE
ESTABLISH TUE EVENING AND A SIMILAR LOW CLOUD REGIME SHOULD OCCUR
TUE EVE INTO WED. THERE IS A 40 PERCENT CHANCE OF -DZ BETWEEN
10Z-15Z.

KBUR...MODERATE CONFIDENCE FOR IFR CONDS AFTER 09Z WITH 50 PERCENT
CHANCE FOR -DZ BETWEEN 09Z AND 16Z. 30 PERCENT CHANCE FOR CIGS TO
SCOUR OUT 2 HOURS AFTER 19Z. LOW CLOUDS SHOULD REDEVELOP ONCE AGAIN
TUE LATE EVEN OR AFTER MIDNIGHT WITH SIMILAR BURNOFF TIMES AND
POSSIBLE DRIZZLE ONCE AGAIN.

&&

.MARINE...18/0200 PM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT
AVIATION...KAPLAN
MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES












000
FXUS66 KLOX 190044
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
545 PM PDT MON AUG 18 2014

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY.  EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE OR ISOLATED SHOWERS.  IT IS
POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE IN LATER IN THE
WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS IN THE
MOUNTAINS.
&&

.SHORT TERM (TONIGHT-THU)...
MAIN FORECAST ISSUES WILL BE DEPTH OF THE MARINE LAYER THE NEXT FEW
DAYS AS WELL AS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS
WED-THU.

UPPER LOW PRESSURE SYSTEM NEAR CRESCENT CITY WILL DROP SOUTHWARD TO
OUR CENTRAL COAST BY TUESDAY AFTERNOON. CURRENTLY OBSERVING A WEAK
JET SPEED MAX ACROSS CENTRAL CALI WHICH IS ENHANCING CIRRUS CLOUDS
IN THAT REGION. CONVECTION WAS STARTING TO FORM NEAR MT SHASTA IN
FAR NORTHERN SECTIONS OF CA EAST OF THE LOW.

TODAY SOUTHWEST CA IS EXPERIENCING A MOSTLY SUNNY DAY WITH HIGH
TEMPERATURES NEAR OR SLIGHTLY BELOW YESTERDAY OVERALL. LOW CLOUDS
ARE HANGING ALONG THE COAST NORTH OF PT CONCEPTION. AS THE LOW DROPS
SOUTHWARD THE MARINE LAYER WILL THICKEN AND ONSHORE PRESSURE
GRADIENTS INCREASE. EXPECT MORE WIDESPREAD STRATUS UP AND DOWN THE
COAST LATE TONIGHT AND PUSHING INTO VALLEYS BY MORNING. WEAK LIFT
COULD RESULT IN PATCHY DRIZZLE AS WELL. MOISTURE LOOKS VERY LIMITED
FOR ANY CONVECTIVE THREAT ON TUESDAY...HOWEVER DID ADD SOME
AFTERNOON CLOUDS TO THE VENTURA COUNTY MOUNTAINS.

COMPUTER MODELS THEN TREAT THE LOW PRESSURE CENTER DIFFERENTLY GOING
INTO WEDNESDAY. THE WRF AND GEM HAVE THE MOST SOUTHERLY TRACK WHILE
THE ECMWF AND GFS KEEP IT MORE INLAND ON WEDNESDAY. THEN ALL MODELS
EXCEPT THE GFS SHIFT THE LOW SOUTHWARD OFF THE SOUTHWEST CA COAST BY
THURSDAY. MARINE LAYER WILL BE DEEPEST ON WEDNESDAY AND HAVE ADDED
PATCHY DRIZZLE IN THE MORNING. SLIGHT INSTABILITY AND MARGINAL
MOISTURE ENOUGH TO CONTINUE IDEA OF SLIGHT CHANCE OF THUNDERSTORMS
ACROSS THE MOUNTAINS ON WEDNESDAY AND ADDED TO THE EASTERN SAN
GABRIEL MOUNTAINS FOR THURSDAY. TEMPERATURES REMAIN COOLER THAN
NORMAL THROUGH WEDNESDAY THEN START TO TURN AROUND ON THURSDAY.

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...19/0045Z.

LATEST ACARS SOUNDING NEAR KLAX WAS AROUND 1200 FT. THIS IS IN LINE
WITH THINKING THAT MARINE LAYER INVERSION WILL DEEPEN OVERNIGHT
ALLOWING FLOW STRATUS TO REACH VALLEY AREAS OVERNIGHT. MARINE LAYER
SHOULD REACH AT LEAST 1500 FT...POSSIBLY HIGHER BY EARLY TUE MORNING.

N OF POINT CONCEPTION...MODERATE CONFIDENCE WITH 00Z TAFS. EXPECT
HIGH IFR CIGS TONIGHT EXCEPT MVFR AT KSBP AFTER 11Z. 50 PERCENT
CHANCE FOR MVFR CIGS FOR KSMX AFTER 12Z. 30 PERCENT CHANCE THAT CIGS
WILL NOT SCOUR OUT ALL DAY. CONTINUE WITH MODERATE TO HIGH
CONFIDENCE FOR IFR/MVFR CIGS TO PUSH INLAND EARLY TUE EVENING ONCE
AGAIN. HIGH CONFIDENCE FOR KPRB TO HAVE HIGH IFR CIGS AFTER 10Z
TONIGHT. LOWER CONFIDENCE WITH SCOUR OUT TIME. +/- 2 HOURS FROM 00Z
TAF.

S OF POINT CONCEPTION...MODERATE CONFIDENCE WITH IFR/MVFR CIGS TO
INITIATE ACROSS LA/VTU/SBA COUNTIES BETWEEN 05-08Z. IFR CIGS WILL
BECOME MVFR FOR MOST ALL COASTAL AREAS BY 14Z FOR KOXR/KSBA AND
REMAIN ABOVE MVFR CONDS FOR KLAX AND KLGB. HIGHER CONFIDENCE THAT
KBUR AND KVNY WILL EXPERIENCE IFR/ TO LOW MVFR CIGS BY 10Z TONIGHT.
GIVE OR TAKE AN HOUR. LOW CLOUDS SHOULD SCOUR OUT WITHIN A COUPLE
HOURS OF 19Z. 20 PERCENT CHANCE THAT CIGS COULD LINGER THROUGH 22Z.
GOOD CHANCE THAT MVFR CIGS WILL SEE ONLY AN HOUR OR TWO OF AFTERNOON
CLEARING ALONG THE VENTURA/SBA COASTAL AREAS. 40 PERCENT CHANCE FOR
CIGS TO REMAIN THE ENTIRE AFTERNOON. EXCEPT EARLIER CLEARING FOR LA
COUNTY COASTAL AREAS.

KLAX...MODERATE CONFIDENCE FOR MVFR CIGS FROM LATE THIS EVENING
THROUGH MOST OF TUESDAY. 40 PERCENT CHANCE THAT MVFR CIGS COULD
LINGER A FEW HOURS PAST 21Z. LOW CLOUDS SHOULD BE QUICK TO RE
ESTABLISH TUE EVENING AND A SIMILAR LOW CLOUD REGIME SHOULD OCCUR
TUE EVE INTO WED. THERE IS A 40 PERCENT CHANCE OF -DZ BETWEEN
10Z-15Z.

KBUR...MODERATE CONFIDENCE FOR IFR CONDS AFTER 09Z WITH 50 PERCENT
CHANCE FOR -DZ BETWEEN 09Z AND 16Z. 30 PERCENT CHANCE FOR CIGS TO
SCOUR OUT 2 HOURS AFTER 19Z. LOW CLOUDS SHOULD REDEVELOP ONCE AGAIN
TUE LATE EVEN OR AFTER MIDNIGHT WITH SIMILAR BURNOFF TIMES AND
POSSIBLE DRIZZLE ONCE AGAIN.

&&

.MARINE...18/0200 PM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT
AVIATION...KAPLAN
MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES













000
FXUS66 KLOX 182116
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
215 PM PDT MON AUG 18 2014

...NEW MARINE DISCUSSION...

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY.  EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE OR ISOLATED SHOWERS.  IT IS
POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE IN LATER IN THE
WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS IN THE
MOUNTAINS.
&&

.SHORT TERM (TONIGHT-THU)...
MAIN FORECAST ISSUES WILL BE DEPTH OF THE MARINE LAYER THE NEXT FEW
DAYS AS WELL AS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS
WED-THU.

UPPER LOW PRESSURE SYSTEM NEAR CRESCENT CITY WILL DROP SOUTHWARD TO
OUR CENTRAL COAST BY TUESDAY AFTERNOON. CURRENTLY OBSERVING A WEAK
JET SPEED MAX ACROSS CENTRAL CALI WHICH IS ENHANCING CIRRUS CLOUDS
IN THAT REGION. CONVECTION WAS STARTING TO FORM NEAR MT SHASTA IN
FAR NORTHERN SECTIONS OF CA EAST OF THE LOW.

TODAY SOUTHWEST CA IS EXPERIENCING A MOSTLY SUNNY DAY WITH HIGH
TEMPERATURES NEAR OR SLIGHTLY BELOW YESTERDAY OVERALL. LOW CLOUDS
ARE HANGING ALONG THE COAST NORTH OF PT CONCEPTION. AS THE LOW DROPS
SOUTHWARD THE MARINE LAYER WILL THICKEN AND ONSHORE PRESSURE
GRADIENTS INCREASE. EXPECT MORE WIDESPREAD STRATUS UP AND DOWN THE
COAST LATE TONIGHT AND PUSHING INTO VALLEYS BY MORNING. WEAK LIFT
COULD RESULT IN PATCHY DRIZZLE AS WELL. MOISTURE LOOKS VERY LIMITED
FOR ANY CONVECTIVE THREAT ON TUESDAY...HOWEVER DID ADD SOME
AFTERNOON CLOUDS TO THE VENTURA COUNTY MOUNTAINS.

COMPUTER MODELS THEN TREAT THE LOW PRESSURE CENTER DIFFERENTLY GOING
INTO WEDNESDAY. THE WRF AND GEM HAVE THE MOST SOUTHERLY TRACK WHILE
THE ECMWF AND GFS KEEP IT MORE INLAND ON WEDNESDAY. THEN ALL MODELS
EXCEPT THE GFS SHIFT THE LOW SOUTHWARD OFF THE SOUTHWEST CA COAST BY
THURSDAY. MARINE LAYER WILL BE DEEPEST ON WEDNESDAY AND HAVE ADDED
PATCHY DRIZZLE IN THE MORNING. SLIGHT INSTABILITY AND MARGINAL
MOISTURE ENOUGH TO CONTINUE IDEA OF SLIGHT CHANCE OF THUNDERSTORMS
ACROSS THE MOUNTAINS ON WEDNESDAY AND ADDED TO THE EASTERN SAN
GABRIEL MOUNTAINS FOR THURSDAY. TEMPERATURES REMAIN COOLER THAN
NORMAL THROUGH WEDNESDAY THEN START TO TURN AROUND ON THURSDAY.

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...18/1800Z.
SYNOPTIC CHANGES OVER THE NEXT 24 HOURS POINT TOWARD GREATER MARINE
CLOUD COVERAGE AND A DEEPENING OF THE MARINE LAYER. THE MORNING
MARINE LAYER DEPTH OF 1000 FEET THIS MORNING SHOULD EXPAND TO 1500
OR POSSIBLY HIGHER BY TUESDAY MORNING. THERE IS A BETTER THAN EVEN
CHANCE THAT THE MARINE LAYER WILL GET PUSHED INTO THE LA VALLEYS BY
A STRONGER ONSHORE GRADIENT BY LATE TONIGHT OR TUESDAY MORNING.
EXPECT MVFR CONDITIONS IN THE COASTAL SECTIONS AND IFR CONDITIONS IN
THE VALLEYS. RELATIVELY GOOD CONFIDENCE IS EXPRESSED IN THIS
SCENARIO WITH ONLY MINOR RESERVATIONS.

KLAX...VFR CONDITIONS WILL YIELD TO MVFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AROUND MIDNIGHT OR SO. THERE IS
A 30 PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE
THAN 2 HOURS.

KBUR...VFR CONDITIONS WILL YIELD TO IFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AFTER MIDNIGHT. THERE IS A 30
PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE THAN
2 HOURS.


&&

.MARINE...18/0200 PM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES










000
FXUS66 KLOX 182116
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
215 PM PDT MON AUG 18 2014

...NEW MARINE DISCUSSION...

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY.  EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE OR ISOLATED SHOWERS.  IT IS
POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE IN LATER IN THE
WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS IN THE
MOUNTAINS.
&&

.SHORT TERM (TONIGHT-THU)...
MAIN FORECAST ISSUES WILL BE DEPTH OF THE MARINE LAYER THE NEXT FEW
DAYS AS WELL AS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS
WED-THU.

UPPER LOW PRESSURE SYSTEM NEAR CRESCENT CITY WILL DROP SOUTHWARD TO
OUR CENTRAL COAST BY TUESDAY AFTERNOON. CURRENTLY OBSERVING A WEAK
JET SPEED MAX ACROSS CENTRAL CALI WHICH IS ENHANCING CIRRUS CLOUDS
IN THAT REGION. CONVECTION WAS STARTING TO FORM NEAR MT SHASTA IN
FAR NORTHERN SECTIONS OF CA EAST OF THE LOW.

TODAY SOUTHWEST CA IS EXPERIENCING A MOSTLY SUNNY DAY WITH HIGH
TEMPERATURES NEAR OR SLIGHTLY BELOW YESTERDAY OVERALL. LOW CLOUDS
ARE HANGING ALONG THE COAST NORTH OF PT CONCEPTION. AS THE LOW DROPS
SOUTHWARD THE MARINE LAYER WILL THICKEN AND ONSHORE PRESSURE
GRADIENTS INCREASE. EXPECT MORE WIDESPREAD STRATUS UP AND DOWN THE
COAST LATE TONIGHT AND PUSHING INTO VALLEYS BY MORNING. WEAK LIFT
COULD RESULT IN PATCHY DRIZZLE AS WELL. MOISTURE LOOKS VERY LIMITED
FOR ANY CONVECTIVE THREAT ON TUESDAY...HOWEVER DID ADD SOME
AFTERNOON CLOUDS TO THE VENTURA COUNTY MOUNTAINS.

COMPUTER MODELS THEN TREAT THE LOW PRESSURE CENTER DIFFERENTLY GOING
INTO WEDNESDAY. THE WRF AND GEM HAVE THE MOST SOUTHERLY TRACK WHILE
THE ECMWF AND GFS KEEP IT MORE INLAND ON WEDNESDAY. THEN ALL MODELS
EXCEPT THE GFS SHIFT THE LOW SOUTHWARD OFF THE SOUTHWEST CA COAST BY
THURSDAY. MARINE LAYER WILL BE DEEPEST ON WEDNESDAY AND HAVE ADDED
PATCHY DRIZZLE IN THE MORNING. SLIGHT INSTABILITY AND MARGINAL
MOISTURE ENOUGH TO CONTINUE IDEA OF SLIGHT CHANCE OF THUNDERSTORMS
ACROSS THE MOUNTAINS ON WEDNESDAY AND ADDED TO THE EASTERN SAN
GABRIEL MOUNTAINS FOR THURSDAY. TEMPERATURES REMAIN COOLER THAN
NORMAL THROUGH WEDNESDAY THEN START TO TURN AROUND ON THURSDAY.

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...18/1800Z.
SYNOPTIC CHANGES OVER THE NEXT 24 HOURS POINT TOWARD GREATER MARINE
CLOUD COVERAGE AND A DEEPENING OF THE MARINE LAYER. THE MORNING
MARINE LAYER DEPTH OF 1000 FEET THIS MORNING SHOULD EXPAND TO 1500
OR POSSIBLY HIGHER BY TUESDAY MORNING. THERE IS A BETTER THAN EVEN
CHANCE THAT THE MARINE LAYER WILL GET PUSHED INTO THE LA VALLEYS BY
A STRONGER ONSHORE GRADIENT BY LATE TONIGHT OR TUESDAY MORNING.
EXPECT MVFR CONDITIONS IN THE COASTAL SECTIONS AND IFR CONDITIONS IN
THE VALLEYS. RELATIVELY GOOD CONFIDENCE IS EXPRESSED IN THIS
SCENARIO WITH ONLY MINOR RESERVATIONS.

KLAX...VFR CONDITIONS WILL YIELD TO MVFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AROUND MIDNIGHT OR SO. THERE IS
A 30 PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE
THAN 2 HOURS.

KBUR...VFR CONDITIONS WILL YIELD TO IFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AFTER MIDNIGHT. THERE IS A 30
PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE THAN
2 HOURS.


&&

.MARINE...18/0200 PM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING. A
SLIGHT SOUTHERLY SWELL WILL AFFECT SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES









000
FXUS66 KLOX 182014
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
115 PM PDT MON AUG 18 2014

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY.  EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE OR ISOLATED SHOWERS.  IT IS
POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE IN LATER IN THE
WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS IN THE
MOUNTAINS.
&&

.SHORT TERM (TONIGHT-THU)...
MAIN FORECAST ISSUES WILL BE DEPTH OF THE MARINE LAYER THE NEXT FEW
DAYS AS WELL AS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS
WED-THU.

UPPER LOW PRESSURE SYSTEM NEAR CRESCENT CITY WILL DROP SOUTHWARD TO
OUR CENTRAL COAST BY TUESDAY AFTERNOON. CURRENTLY OBSERVING A WEAK
JET SPEED MAX ACROSS CENTRAL CALI WHICH IS ENHANCING CIRRUS CLOUDS
IN THAT REGION. CONVECTION WAS STARTING TO FORM NEAR MT SHASTA IN
FAR NORTHERN SECTIONS OF CA EAST OF THE LOW.

TODAY SOUTHWEST CA IS EXPERIENCING A MOSTLY SUNNY DAY WITH HIGH
TEMPERATURES NEAR OR SLIGHTLY BELOW YESTERDAY OVERALL. LOW CLOUDS
ARE HANGING ALONG THE COAST NORTH OF PT CONCEPTION. AS THE LOW DROPS
SOUTHWARD THE MARINE LAYER WILL THICKEN AND ONSHORE PRESSURE
GRADIENTS INCREASE. EXPECT MORE WIDESPREAD STRATUS UP AND DOWN THE
COAST LATE TONIGHT AND PUSHING INTO VALLEYS BY MORNING. WEAK LIFT
COULD RESULT IN PATCHY DRIZZLE AS WELL. MOISTURE LOOKS VERY LIMITED
FOR ANY CONVECTIVE THREAT ON TUESDAY...HOWEVER DID ADD SOME
AFTERNOON CLOUDS TO THE VENTURA COUNTY MOUNTAINS.

COMPUTER MODELS THEN TREAT THE LOW PRESSURE CENTER DIFFERENTLY GOING
INTO WEDNESDAY. THE WRF AND GEM HAVE THE MOST SOUTHERLY TRACK WHILE
THE ECMWF AND GFS KEEP IT MORE INLAND ON WEDNESDAY. THEN ALL MODELS
EXCEPT THE GFS SHIFT THE LOW SOUTHWARD OFF THE SOUTHWEST CA COAST BY
THURSDAY. MARINE LAYER WILL BE DEEPEST ON WEDNESDAY AND HAVE ADDED
PATCHY DRIZZLE IN THE MORNING. SLIGHT INSTABILITY AND MARGINAL
MOISTURE ENOUGH TO CONTINUE IDEA OF SLIGHT CHANCE OF THUNDERSTORMS
ACROSS THE MOUNTAINS ON WEDNESDAY AND ADDED TO THE EASTERN SAN
GABRIEL MOUNTAINS FOR THURSDAY. TEMPERATURES REMAIN COOLER THAN
NORMAL THROUGH WEDNESDAY THEN START TO TURN AROUND ON THURSDAY.

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...18/1800Z.
SYNOPTIC CHANGES OVER THE NEXT 24 HOURS POINT TOWARD GREATER MARINE
CLOUD COVERAGE AND A DEEPENING OF THE MARINE LAYER. THE MORNING
MARINE LAYER DEPTH OF 1000 FEET THIS MORNING SHOULD EXPAND TO 1500
OR POSSIBLY HIGHER BY TUESDAY MORNING. THERE IS A BETTER THAN EVEN
CHANCE THAT THE MARINE LAYER WILL GET PUSHED INTO THE LA VALLEYS BY
A STRONGER ONSHORE GRADIENT BY LATE TONIGHT OR TUESDAY MORNING.
EXPECT MVFR CONDITIONS IN THE COASTAL SECTIONS AND IFR CONDITIONS IN
THE VALLEYS. RELATIVELY GOOD CONFIDENCE IS EXPRESSED IN THIS
SCENARIO WITH ONLY MINOR RESERVATIONS.

KLAX...VFR CONDITIONS WILL YIELD TO MVFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AROUND MIDNIGHT OR SO. THERE IS
A 30 PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE
THAN 2 HOURS.

KBUR...VFR CONDITIONS WILL YIELD TO IFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AFTER MIDNIGHT. THERE IS A 30
PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE THAN
2 HOURS.


&&

.MARINE...18/0900 AM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING IN
SPITE OF A BRIEF MIDDAY LULL. A SLIGHT SOUTHERLY SWELL WILL AFFECT
SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES






000
FXUS66 KLOX 182014
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
115 PM PDT MON AUG 18 2014

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL MOVE SOUTH AND STRONGLY
INFLUENCE THE WEATHER THROUGH THURSDAY.  EXPECT INCREASED ONSHORE
FLOW...MORE CLOUDS...AND A DEEPER MARINE LAYER.  THE RESULT IS A
COOLING TREND AND POSSIBLE DRIZZLE OR ISOLATED SHOWERS.  IT IS
POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE IN LATER IN THE
WEEK...BRINGING A SLIGHT CHANCE OF AFTERNOON THUNDERSTORMS IN THE
MOUNTAINS.
&&

.SHORT TERM (TONIGHT-THU)...
MAIN FORECAST ISSUES WILL BE DEPTH OF THE MARINE LAYER THE NEXT FEW
DAYS AS WELL AS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS
WED-THU.

UPPER LOW PRESSURE SYSTEM NEAR CRESCENT CITY WILL DROP SOUTHWARD TO
OUR CENTRAL COAST BY TUESDAY AFTERNOON. CURRENTLY OBSERVING A WEAK
JET SPEED MAX ACROSS CENTRAL CALI WHICH IS ENHANCING CIRRUS CLOUDS
IN THAT REGION. CONVECTION WAS STARTING TO FORM NEAR MT SHASTA IN
FAR NORTHERN SECTIONS OF CA EAST OF THE LOW.

TODAY SOUTHWEST CA IS EXPERIENCING A MOSTLY SUNNY DAY WITH HIGH
TEMPERATURES NEAR OR SLIGHTLY BELOW YESTERDAY OVERALL. LOW CLOUDS
ARE HANGING ALONG THE COAST NORTH OF PT CONCEPTION. AS THE LOW DROPS
SOUTHWARD THE MARINE LAYER WILL THICKEN AND ONSHORE PRESSURE
GRADIENTS INCREASE. EXPECT MORE WIDESPREAD STRATUS UP AND DOWN THE
COAST LATE TONIGHT AND PUSHING INTO VALLEYS BY MORNING. WEAK LIFT
COULD RESULT IN PATCHY DRIZZLE AS WELL. MOISTURE LOOKS VERY LIMITED
FOR ANY CONVECTIVE THREAT ON TUESDAY...HOWEVER DID ADD SOME
AFTERNOON CLOUDS TO THE VENTURA COUNTY MOUNTAINS.

COMPUTER MODELS THEN TREAT THE LOW PRESSURE CENTER DIFFERENTLY GOING
INTO WEDNESDAY. THE WRF AND GEM HAVE THE MOST SOUTHERLY TRACK WHILE
THE ECMWF AND GFS KEEP IT MORE INLAND ON WEDNESDAY. THEN ALL MODELS
EXCEPT THE GFS SHIFT THE LOW SOUTHWARD OFF THE SOUTHWEST CA COAST BY
THURSDAY. MARINE LAYER WILL BE DEEPEST ON WEDNESDAY AND HAVE ADDED
PATCHY DRIZZLE IN THE MORNING. SLIGHT INSTABILITY AND MARGINAL
MOISTURE ENOUGH TO CONTINUE IDEA OF SLIGHT CHANCE OF THUNDERSTORMS
ACROSS THE MOUNTAINS ON WEDNESDAY AND ADDED TO THE EASTERN SAN
GABRIEL MOUNTAINS FOR THURSDAY. TEMPERATURES REMAIN COOLER THAN
NORMAL THROUGH WEDNESDAY THEN START TO TURN AROUND ON THURSDAY.

.LONG TERM (FRI-MON)...
GENERALLY EXPECT A SLOW WARMING TREND DURING THE EXTENDED FORECAST.
THE LOW PRESSURE SYSTEM EITHER FILLS OR SHIFTS EASTWARD BY FRIDAY.
CONFIDENCE IN THIS TIME FRAME IS LOW AS THE ECMWF AND GFS HAVE
DIFFERENT IDEAS BETWEEN EITHER A BUILDING RIDGE OR A TROUGH
EXTENDING FROM THE NORTHERN ROCKIES TO THE GREAT BASIN,
RESPECTIVELY. FAVOR THE WARMER ECMWF MODEL. OTHER ITEM OF NOTE IS
THE EXTRA-TROPICAL LOW PRESSURE SYSTEM...CURRENTLY TROPICAL
DEPRESSION TWELVE-E...THAT MOVES NORTHWEST AND COULD ENTRAIN SOME
HIGHER LEVEL MOISTURE ACROSS SOUTHERN CALI SOMETIME EARLY NEXT WEEK.

&&

.AVIATION...18/1800Z.
SYNOPTIC CHANGES OVER THE NEXT 24 HOURS POINT TOWARD GREATER MARINE
CLOUD COVERAGE AND A DEEPENING OF THE MARINE LAYER. THE MORNING
MARINE LAYER DEPTH OF 1000 FEET THIS MORNING SHOULD EXPAND TO 1500
OR POSSIBLY HIGHER BY TUESDAY MORNING. THERE IS A BETTER THAN EVEN
CHANCE THAT THE MARINE LAYER WILL GET PUSHED INTO THE LA VALLEYS BY
A STRONGER ONSHORE GRADIENT BY LATE TONIGHT OR TUESDAY MORNING.
EXPECT MVFR CONDITIONS IN THE COASTAL SECTIONS AND IFR CONDITIONS IN
THE VALLEYS. RELATIVELY GOOD CONFIDENCE IS EXPRESSED IN THIS
SCENARIO WITH ONLY MINOR RESERVATIONS.

KLAX...VFR CONDITIONS WILL YIELD TO MVFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AROUND MIDNIGHT OR SO. THERE IS
A 30 PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE
THAN 2 HOURS.

KBUR...VFR CONDITIONS WILL YIELD TO IFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AFTER MIDNIGHT. THERE IS A 30
PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE THAN
2 HOURS.


&&

.MARINE...18/0900 AM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING IN
SPITE OF A BRIEF MIDDAY LULL. A SLIGHT SOUTHERLY SWELL WILL AFFECT
SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT
AVIATION/MARINE...SWEET
SYNOPSIS...JLD

WWW.WEATHER.GOV/LOSANGELES







000
FXUS66 KLOX 181928
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1225 PM PDT MON AUG 18 2014

...NEW AVIATION DISCUSSION...

.SYNOPSIS...
AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&
.UPDATE...
MINOR ADJUSTMENTS TO MAXIMUM TEMPERATURES TODAY AS MAJORITY OF THE
SOUTH COAST REMAINED CLOUD-FREE AND WILL NOT BE QUITE AS COOL AS
EXPECTED. LAX AND SIMI PROFILERS SHOW LITTLE SIGNIFICANT COOLING
COMPARED TO YESTERDAY. SOUNDINGS SHOW MARINE LAYER DEEPENED TO ABOUT
1500 FEET AND TEMPERATURES AT THAT ELEVATION ARE ABOUT 10 DEGREES
COOLER...IMPACTING THE FOOTHILLS AND LOWER MOUNTAIN AREAS.

AN UPPER TROUGH WAS OFF THE NORTHWEST BAJA COAST WITH SOUTHWEST FLOW
ALOFT OVER SOUTHERN CALI. SOME CONVECTIVE LEFTOVERS WERE OVER THE
HIGH DESERTS THIS MORNING BUT NO MODELS INDICATE THIS ACTIVITY WILL
HAVE ANY INFLUENCE ON OUR WEATHER TODAY. ISOLATED CELLS WILL LIKELY
FORM NEAR BIG BEAR AND LOCATIONS EASTWARD THIS AFTERNOON WHILE WE
STAY DRY.

A LOW PRESSURE SYSTEM DROPS FROM NORTHWEST CALI TO THE CENTRAL COAST
ON TUESDAY. THIS INCREASES THE SOUTHWEST TO WEST FLOW OVER THE
REGION AND ONSHORE PRESSURE GRADIENTS ARE EXPECTED TO BE STRONGER
TUESDAY. THE MARINE LAYER WILL DEEPEN WITH MORE ORGANIZED CLOUD
COVERAGE FOR THE SOUTH COAST TOMORROW AND A GENERAL DECLINE IN
TEMPERATURES. HIGH-BASED MOISTURE NEAR 20K FEET WILL GENERATE
SOME CLOUD BUILD-UPS OVER THE VENTURA MOUNTAINS TUESDAY AFTERNOON IN
FAVORABLE DIFFLUENT AREA OF THE LOW PRESSURE SYSTEM...BUT LOOKS TOO
DRY FOR CONVECTION AT THIS TIME.

***FROM PREVIOUS DISCUSSION***

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...18/1800Z.
SYNOPTIC CHANGES OVER THE NEXT 24 HOURS POINT TOWARD GREATER MARINE
CLOUD COVERAGE AND A DEEPENING OF THE MARINE LAYER. THE MORNING
MARINE LAYER DEPTH OF 1000 FEET THIS MORNING SHOULD EXPAND TO 1500
OR POSSIBLY HIGHER BY TUESDAY MORNING. THERE IS A BETTER THAN EVEN
CHANCE THAT THE MARINE LAYER WILL GET PUSHED INTO THE LA VALLEYS BY
A STRONGER ONSHORE GRADIENT BY LATE TONIGHT OR TUESDAY MORNING.
EXPECT MVFR CONDITIONS IN THE COASTAL SECTIONS AND IFR CONDITIONS IN
THE VALLEYS. RELATIVELY GOOD CONFIDENCE IS EXPRESSED IN THIS
SCENARIO WITH ONLY MINOR RESERVATIONS.

KLAX...VFR CONDITIONS WILL YIELD TO MVFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AROUND MIDNIGHT OR SO. THERE IS
A 30 PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE
THAN 2 HOURS.

KBUR...VFR CONDITIONS WILL YIELD TO IFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AFTER MIDNIGHT. THERE IS A 30
PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE THAN
2 HOURS.

&&

.MARINE...18/0900 AM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING IN
SPITE OF A BRIEF MIDDAY LULL. A SLIGHT SOUTHERLY SWELL WILL AFFECT
SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...SWEET
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES


















000
FXUS66 KLOX 181928
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1225 PM PDT MON AUG 18 2014

...NEW AVIATION DISCUSSION...

.SYNOPSIS...
AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&
.UPDATE...
MINOR ADJUSTMENTS TO MAXIMUM TEMPERATURES TODAY AS MAJORITY OF THE
SOUTH COAST REMAINED CLOUD-FREE AND WILL NOT BE QUITE AS COOL AS
EXPECTED. LAX AND SIMI PROFILERS SHOW LITTLE SIGNIFICANT COOLING
COMPARED TO YESTERDAY. SOUNDINGS SHOW MARINE LAYER DEEPENED TO ABOUT
1500 FEET AND TEMPERATURES AT THAT ELEVATION ARE ABOUT 10 DEGREES
COOLER...IMPACTING THE FOOTHILLS AND LOWER MOUNTAIN AREAS.

AN UPPER TROUGH WAS OFF THE NORTHWEST BAJA COAST WITH SOUTHWEST FLOW
ALOFT OVER SOUTHERN CALI. SOME CONVECTIVE LEFTOVERS WERE OVER THE
HIGH DESERTS THIS MORNING BUT NO MODELS INDICATE THIS ACTIVITY WILL
HAVE ANY INFLUENCE ON OUR WEATHER TODAY. ISOLATED CELLS WILL LIKELY
FORM NEAR BIG BEAR AND LOCATIONS EASTWARD THIS AFTERNOON WHILE WE
STAY DRY.

A LOW PRESSURE SYSTEM DROPS FROM NORTHWEST CALI TO THE CENTRAL COAST
ON TUESDAY. THIS INCREASES THE SOUTHWEST TO WEST FLOW OVER THE
REGION AND ONSHORE PRESSURE GRADIENTS ARE EXPECTED TO BE STRONGER
TUESDAY. THE MARINE LAYER WILL DEEPEN WITH MORE ORGANIZED CLOUD
COVERAGE FOR THE SOUTH COAST TOMORROW AND A GENERAL DECLINE IN
TEMPERATURES. HIGH-BASED MOISTURE NEAR 20K FEET WILL GENERATE
SOME CLOUD BUILD-UPS OVER THE VENTURA MOUNTAINS TUESDAY AFTERNOON IN
FAVORABLE DIFFLUENT AREA OF THE LOW PRESSURE SYSTEM...BUT LOOKS TOO
DRY FOR CONVECTION AT THIS TIME.

***FROM PREVIOUS DISCUSSION***

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...18/1800Z.
SYNOPTIC CHANGES OVER THE NEXT 24 HOURS POINT TOWARD GREATER MARINE
CLOUD COVERAGE AND A DEEPENING OF THE MARINE LAYER. THE MORNING
MARINE LAYER DEPTH OF 1000 FEET THIS MORNING SHOULD EXPAND TO 1500
OR POSSIBLY HIGHER BY TUESDAY MORNING. THERE IS A BETTER THAN EVEN
CHANCE THAT THE MARINE LAYER WILL GET PUSHED INTO THE LA VALLEYS BY
A STRONGER ONSHORE GRADIENT BY LATE TONIGHT OR TUESDAY MORNING.
EXPECT MVFR CONDITIONS IN THE COASTAL SECTIONS AND IFR CONDITIONS IN
THE VALLEYS. RELATIVELY GOOD CONFIDENCE IS EXPRESSED IN THIS
SCENARIO WITH ONLY MINOR RESERVATIONS.

KLAX...VFR CONDITIONS WILL YIELD TO MVFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AROUND MIDNIGHT OR SO. THERE IS
A 30 PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE
THAN 2 HOURS.

KBUR...VFR CONDITIONS WILL YIELD TO IFR CONDITIONS TONIGHT AS THE
MARINE CLOUDS OVERTAKE THE AIRFIELD AFTER MIDNIGHT. THERE IS A 30
PERCENT CHANCE OF THE TAF TIMING DIFFERING FROM REALITY BY MORE THAN
2 HOURS.

&&

.MARINE...18/0900 AM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING IN
SPITE OF A BRIEF MIDDAY LULL. A SLIGHT SOUTHERLY SWELL WILL AFFECT
SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...SWEET
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES



















000
FXUS66 KLOX 181641
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
940 AM PDT MON AUG 18 2014

.SYNOPSIS...
AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&
.UPDATE...
MINOR ADJUSTMENTS TO MAXIMUM TEMPERATURES TODAY AS MAJORITY OF THE
SOUTH COAST REMAINED CLOUD-FREE AND WILL NOT BE QUITE AS COOL AS
EXPECTED. LAX AND SIMI PROFILERS SHOW LITTLE SIGNIFICANT COOLING
COMPARED TO YESTERDAY. SOUNDINGS SHOW MARINE LAYER DEEPENED TO ABOUT
1500 FEET AND TEMPERATURES AT THAT ELEVATION ARE ABOUT 10 DEGREES
COOLER...IMPACTING THE FOOTHILLS AND LOWER MOUNTAIN AREAS.

AN UPPER TROUGH WAS OFF THE NORTHWEST BAJA COAST WITH SOUTHWEST FLOW
ALOFT OVER SOUTHERN CALI. SOME CONVECTIVE LEFTOVERS WERE OVER THE
HIGH DESERTS THIS MORNING BUT NO MODELS INDICATE THIS ACTIVITY WILL
HAVE ANY INFLUENCE ON OUR WEATHER TODAY. ISOLATED CELLS WILL LIKELY
FORM NEAR BIG BEAR AND LOCATIONS EASTWARD THIS AFTERNOON WHILE WE
STAY DRY.

A LOW PRESSURE SYSTEM DROPS FROM NORTHWEST CALI TO THE CENTRAL COAST
ON TUESDAY. THIS INCREASES THE SOUTHWEST TO WEST FLOW OVER THE
REGION AND ONSHORE PRESSURE GRADIENTS ARE EXPECTED TO BE STRONGER
TUESDAY. THE MARINE LAYER WILL DEEPEN WITH MORE ORGANIZED CLOUD
COVERAGE FOR THE SOUTH COAST TOMORROW AND A GENERAL DECLINE IN
TEMPERATURES. HIGH-BASED MOISTURE NEAR 20K FEET WILL GENERATE
SOME CLOUD BUILD-UPS OVER THE VENTURA MOUNTAINS TUESDAY AFTERNOON IN
FAVORABLE DIFFLUENT AREA OF THE LOW PRESSURE SYSTEM...BUT LOOKS TOO
DRY FOR CONVECTION AT THIS TIME.

***FROM PREVIOUS DISCUSSION***

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/1135Z
WIDESPREAD STRATUS ON THE CENTRAL COAST AND IN THE SANTA YNEZ VALLEY
THIS MORNING. EXPECT STRATUS TO FILL IN ACROSS COASTAL SECTIONS OF
L.A. AND VTU COUNTIES BY DAYBREAK. CONDS WILL BE MOSTLY IFR TO
LIFR...EXCEPT MOST LIKELY MVFR ACROSS THE L.A. COUNTY COAST. EXPECT
SKIES TO CLEAR BY MID OR LATE MORNING IN MOST AREAS. STRATUS SHOULD
BE MORE WIDESPREAD TONIGHT...AND WITH A DEEPENING MARINE
LAYER...EXPECT CLOUDS TO PUSH INTO THE L.A. COUNTY VLYS. CONDS
SHOULD BE MOSTLY IFR...EXCEPT MVFR ON THE L.A. COUNTY COASTAL
PLAIN...AND RIGHT NEAR THE THRESHOLD OF IFR/MVFR ACROSS CSTL
SECTIONS OF VTU AND SRN SBA COUNTIES.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CONDS WILL REMAIN VFR THIS MORNING. THERE IS A
20 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 06Z ON THE 19TH
(TONIGHT).

KBUR...HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20 PERCENT CHANCE
THAT CIGS TONIGHT WILL ARRIVE AS EARLY AS 09Z ON THE 19TH (TONIGHT).

&&

.MARINE...18/0900 AM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING IN
SPITE OF A BRIEF MIDDAY LULL. A SLIGHT SOUTHERLY SWELL WILL AFFECT
SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...DB/SWEET
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES















000
FXUS66 KLOX 181641
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
940 AM PDT MON AUG 18 2014

.SYNOPSIS...
AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&
.UPDATE...
MINOR ADJUSTMENTS TO MAXIMUM TEMPERATURES TODAY AS MAJORITY OF THE
SOUTH COAST REMAINED CLOUD-FREE AND WILL NOT BE QUITE AS COOL AS
EXPECTED. LAX AND SIMI PROFILERS SHOW LITTLE SIGNIFICANT COOLING
COMPARED TO YESTERDAY. SOUNDINGS SHOW MARINE LAYER DEEPENED TO ABOUT
1500 FEET AND TEMPERATURES AT THAT ELEVATION ARE ABOUT 10 DEGREES
COOLER...IMPACTING THE FOOTHILLS AND LOWER MOUNTAIN AREAS.

AN UPPER TROUGH WAS OFF THE NORTHWEST BAJA COAST WITH SOUTHWEST FLOW
ALOFT OVER SOUTHERN CALI. SOME CONVECTIVE LEFTOVERS WERE OVER THE
HIGH DESERTS THIS MORNING BUT NO MODELS INDICATE THIS ACTIVITY WILL
HAVE ANY INFLUENCE ON OUR WEATHER TODAY. ISOLATED CELLS WILL LIKELY
FORM NEAR BIG BEAR AND LOCATIONS EASTWARD THIS AFTERNOON WHILE WE
STAY DRY.

A LOW PRESSURE SYSTEM DROPS FROM NORTHWEST CALI TO THE CENTRAL COAST
ON TUESDAY. THIS INCREASES THE SOUTHWEST TO WEST FLOW OVER THE
REGION AND ONSHORE PRESSURE GRADIENTS ARE EXPECTED TO BE STRONGER
TUESDAY. THE MARINE LAYER WILL DEEPEN WITH MORE ORGANIZED CLOUD
COVERAGE FOR THE SOUTH COAST TOMORROW AND A GENERAL DECLINE IN
TEMPERATURES. HIGH-BASED MOISTURE NEAR 20K FEET WILL GENERATE
SOME CLOUD BUILD-UPS OVER THE VENTURA MOUNTAINS TUESDAY AFTERNOON IN
FAVORABLE DIFFLUENT AREA OF THE LOW PRESSURE SYSTEM...BUT LOOKS TOO
DRY FOR CONVECTION AT THIS TIME.

***FROM PREVIOUS DISCUSSION***

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/1135Z
WIDESPREAD STRATUS ON THE CENTRAL COAST AND IN THE SANTA YNEZ VALLEY
THIS MORNING. EXPECT STRATUS TO FILL IN ACROSS COASTAL SECTIONS OF
L.A. AND VTU COUNTIES BY DAYBREAK. CONDS WILL BE MOSTLY IFR TO
LIFR...EXCEPT MOST LIKELY MVFR ACROSS THE L.A. COUNTY COAST. EXPECT
SKIES TO CLEAR BY MID OR LATE MORNING IN MOST AREAS. STRATUS SHOULD
BE MORE WIDESPREAD TONIGHT...AND WITH A DEEPENING MARINE
LAYER...EXPECT CLOUDS TO PUSH INTO THE L.A. COUNTY VLYS. CONDS
SHOULD BE MOSTLY IFR...EXCEPT MVFR ON THE L.A. COUNTY COASTAL
PLAIN...AND RIGHT NEAR THE THRESHOLD OF IFR/MVFR ACROSS CSTL
SECTIONS OF VTU AND SRN SBA COUNTIES.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CONDS WILL REMAIN VFR THIS MORNING. THERE IS A
20 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 06Z ON THE 19TH
(TONIGHT).

KBUR...HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20 PERCENT CHANCE
THAT CIGS TONIGHT WILL ARRIVE AS EARLY AS 09Z ON THE 19TH (TONIGHT).

&&

.MARINE...18/0900 AM

WINDS WILL CONTINUE AT SMALL CRAFT ADVISORY LEVELS ACROSS THE
SOUTHERN TWO THIRDS OF THE OUTER WATERS THROUGH THIS EVENING IN
SPITE OF A BRIEF MIDDAY LULL. A SLIGHT SOUTHERLY SWELL WILL AFFECT
SOUTH FACING BEACHES THIS WEEK.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...DB/SWEET
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES
















000
FXUS66 KLOX 181627
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
925 AM PDT MON AUG 18 2014

.SYNOPSIS...
AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&
.UPDATE...
MINOR ADJUSTMENTS TO MAXIMUM TEMPERATURES TODAY AS MAJORITY OF THE
SOUTH COAST REMAINED CLOUD-FREE AND WILL NOT BE QUITE AS COOL AS
EXPECTED. LAX AND SIMI PROFILERS SHOW LITTLE SIGNIFICANT COOLING
COMPARED TO YESTERDAY. SOUNDINGS SHOW MARINE LAYER DEEPENED TO ABOUT
1500 FEET AND TEMPERATURES AT THAT ELEVATION ARE ABOUT 10 DEGREES
COOLER...IMPACTING THE FOOTHILLS AND LOWER MOUNTAIN AREAS.

AN UPPER TROUGH WAS OFF THE NORTHWEST BAJA COAST WITH SOUTHWEST FLOW
ALOFT OVER SOUTHERN CALI. SOME CONVECTIVE LEFTOVERS WERE OVER THE
HIGH DESERTS THIS MORNING BUT NO MODELS INDICATE THIS ACTIVITY WILL
HAVE ANY INFLUENCE ON OUR WEATHER TODAY. ISOLATED CELLS WILL LIKELY
FORM NEAR BIG BEAR AND LOCATIONS EASTWARD THIS AFTERNOON WHILE WE
STAY DRY.

A LOW PRESSURE SYSTEM DROPS FROM NORTHWEST CALI TO THE CENTRAL COAST
ON TUESDAY. THIS INCREASES THE SOUTHWEST TO WEST FLOW OVER THE
REGION AND ONSHORE PRESSURE GRADIENTS ARE EXPECTED TO BE STRONGER
TUESDAY. THE MARINE LAYER WILL DEEPEN WITH MORE ORGANIZED CLOUD
COVERAGE FOR THE SOUTH COAST TOMORROW AND A GENERAL DECLINE IN
TEMPERATURES. HIGH-BASED MOISTURE NEAR 20K FEET WILL GENERATE
SOME CLOUD BUILD-UPS OVER THE VENTURA MOUNTAINS TUESDAY AFTERNOON IN
FAVORABLE DIFFLUENT AREA OF THE LOW PRESSURE SYSTEM...BUT LOOKS TOO
DRY FOR CONVECTION AT THIS TIME.

***FROM PREVIOUS DISCUSSION***

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/1135Z
WIDESPREAD STRATUS ON THE CENTRAL COAST AND IN THE SANTA YNEZ VALLEY
THIS MORNING. EXPECT STRATUS TO FILL IN ACROSS COASTAL SECTIONS OF
L.A. AND VTU COUNTIES BY DAYBREAK. CONDS WILL BE MOSTLY IFR TO
LIFR...EXCEPT MOST LIKELY MVFR ACROSS THE L.A. COUNTY COAST. EXPECT
SKIES TO CLEAR BY MID OR LATE MORNING IN MOST AREAS. STRATUS SHOULD
BE MORE WIDESPREAD TONIGHT...AND WITH A DEEPENING MARINE
LAYER...EXPECT CLOUDS TO PUSH INTO THE L.A. COUNTY VLYS. CONDS
SHOULD BE MOSTLY IFR...EXCEPT MVFR ON THE L.A. COUNTY COASTAL
PLAIN...AND RIGHT NEAR THE THRESHOLD OF IFR/MVFR ACROSS CSTL
SECTIONS OF VTU AND SRN SBA COUNTIES.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CONDS WILL REMAIN VFR THIS MORNING. THERE IS A
20 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 06Z ON THE 19TH
(TONIGHT).

KBUR...HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20 PERCENT CHANCE
THAT CIGS TONIGHT WILL ARRIVE AS EARLY AS 09Z ON THE 19TH (TONIGHT).

&&

.MARINE...
18/300 AM PDT.

WINDS WILL LIKELY DIMINISH BELOW SMALL CRAFT ADVISORY LEVELS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS BY MID MORNING.
THERE IS A 20 TO 30 PERCENT CHANCE OF SMALL CRAFT ADVISORY CONDS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS AND THE WESTERN
PORTION OF THE SBA CHANNEL LATE THIS AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...DB
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES












000
FXUS66 KLOX 181627
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
925 AM PDT MON AUG 18 2014

.SYNOPSIS...
AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&
.UPDATE...
MINOR ADJUSTMENTS TO MAXIMUM TEMPERATURES TODAY AS MAJORITY OF THE
SOUTH COAST REMAINED CLOUD-FREE AND WILL NOT BE QUITE AS COOL AS
EXPECTED. LAX AND SIMI PROFILERS SHOW LITTLE SIGNIFICANT COOLING
COMPARED TO YESTERDAY. SOUNDINGS SHOW MARINE LAYER DEEPENED TO ABOUT
1500 FEET AND TEMPERATURES AT THAT ELEVATION ARE ABOUT 10 DEGREES
COOLER...IMPACTING THE FOOTHILLS AND LOWER MOUNTAIN AREAS.

AN UPPER TROUGH WAS OFF THE NORTHWEST BAJA COAST WITH SOUTHWEST FLOW
ALOFT OVER SOUTHERN CALI. SOME CONVECTIVE LEFTOVERS WERE OVER THE
HIGH DESERTS THIS MORNING BUT NO MODELS INDICATE THIS ACTIVITY WILL
HAVE ANY INFLUENCE ON OUR WEATHER TODAY. ISOLATED CELLS WILL LIKELY
FORM NEAR BIG BEAR AND LOCATIONS EASTWARD THIS AFTERNOON WHILE WE
STAY DRY.

A LOW PRESSURE SYSTEM DROPS FROM NORTHWEST CALI TO THE CENTRAL COAST
ON TUESDAY. THIS INCREASES THE SOUTHWEST TO WEST FLOW OVER THE
REGION AND ONSHORE PRESSURE GRADIENTS ARE EXPECTED TO BE STRONGER
TUESDAY. THE MARINE LAYER WILL DEEPEN WITH MORE ORGANIZED CLOUD
COVERAGE FOR THE SOUTH COAST TOMORROW AND A GENERAL DECLINE IN
TEMPERATURES. HIGH-BASED MOISTURE NEAR 20K FEET WILL GENERATE
SOME CLOUD BUILD-UPS OVER THE VENTURA MOUNTAINS TUESDAY AFTERNOON IN
FAVORABLE DIFFLUENT AREA OF THE LOW PRESSURE SYSTEM...BUT LOOKS TOO
DRY FOR CONVECTION AT THIS TIME.

***FROM PREVIOUS DISCUSSION***

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/1135Z
WIDESPREAD STRATUS ON THE CENTRAL COAST AND IN THE SANTA YNEZ VALLEY
THIS MORNING. EXPECT STRATUS TO FILL IN ACROSS COASTAL SECTIONS OF
L.A. AND VTU COUNTIES BY DAYBREAK. CONDS WILL BE MOSTLY IFR TO
LIFR...EXCEPT MOST LIKELY MVFR ACROSS THE L.A. COUNTY COAST. EXPECT
SKIES TO CLEAR BY MID OR LATE MORNING IN MOST AREAS. STRATUS SHOULD
BE MORE WIDESPREAD TONIGHT...AND WITH A DEEPENING MARINE
LAYER...EXPECT CLOUDS TO PUSH INTO THE L.A. COUNTY VLYS. CONDS
SHOULD BE MOSTLY IFR...EXCEPT MVFR ON THE L.A. COUNTY COASTAL
PLAIN...AND RIGHT NEAR THE THRESHOLD OF IFR/MVFR ACROSS CSTL
SECTIONS OF VTU AND SRN SBA COUNTIES.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CONDS WILL REMAIN VFR THIS MORNING. THERE IS A
20 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 06Z ON THE 19TH
(TONIGHT).

KBUR...HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20 PERCENT CHANCE
THAT CIGS TONIGHT WILL ARRIVE AS EARLY AS 09Z ON THE 19TH (TONIGHT).

&&

.MARINE...
18/300 AM PDT.

WINDS WILL LIKELY DIMINISH BELOW SMALL CRAFT ADVISORY LEVELS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS BY MID MORNING.
THERE IS A 20 TO 30 PERCENT CHANCE OF SMALL CRAFT ADVISORY CONDS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS AND THE WESTERN
PORTION OF THE SBA CHANNEL LATE THIS AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...BOLDT/RORKE
AVIATION/MARINE...DB
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES













000
FXUS66 KLOX 181133
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
435 AM PDT MON AUG 18 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&

.SHORT TERM (TODAY-WED)...
MARINE LAYER IS 1300 FEET AND PROBABLY A LITTLE LOWER NORTH OF POINT
CONCEPTION. THERE IS A 3 MB ONSHORE PUSH TO KDAG BUT ONLY A 1 MB
PUSH TO KBFL. THERE IS AN UPPER LOW OVER CRESCENT CITY BUT THE LIFT
ASSOC WITH THIS LOW IS NOT NEAR ENOUGH TO SOCAL TO HELP FORM MARINE
LAYER STRATUS. AS A RESULT CLOUDS HAVE BEEN SLOW TO FORM SOUTH OF
POINT CONCEPTION. THERE SHOULD BE SOME LOW CLOUDS ACROSS THE LA
COAST BUT THATS ABOUT IT. THE CENTRAL COAST AND SANTA YNEZ VLY A
CHOCK FULL OF LOW CLOUDS AND THERE IS EVEN SOME DENSE FOG. THE LOW
WILL MOVE CLOSE TO THE AREA TODAY AND THE FALLING HGTS AS WELL AS
INCREASING ONSHORE FLOW WILL KICK OFF A COOLING TREND OVER THE AREA.

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/1135Z
WIDESPREAD STRATUS ON THE CENTRAL COAST AND IN THE SANTA YNEZ VALLEY
THIS MORNING. EXPECT STRATUS TO FILL IN ACROSS COASTAL SECTIONS OF
L.A. AND VTU COUNTIES BY DAYBREAK. CONDS WILL BE MOSTLY IFR TO
LIFR...EXCEPT MOST LIKELY MVFR ACROSS THE L.A. COUNTY COAST. EXPECT
SKIES TO CLEAR BY MID OR LATE MORNING IN MOST AREAS. STRATUS SHOULD
BE MORE WIDESPREAD TONIGHT...AND WITH A DEEPENING MARINE
LAYER...EXPECT CLOUDS TO PUSH INTO THE L.A. COUNTY VLYS. CONDS
SHOULD BE MOSTLY IFR...EXCEPT MVFR ON THE L.A. COUNTY COASTAL
PLAIN...AND RIGHT NEAR THE THRESHOLD OF IFR/MVFR ACROSS CSTL
SECTIONS OF VTU AND SRN SBA COUNTIES.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CONDS WILL REMAIN VFR THIS MORNING. THERE IS A
20 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 06Z ON THE 19TH
(TONIGHT).

KBUR...HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20 PERCENT CHANCE
THAT CIGS TONIGHT WILL ARRIVE AS EARLY AS 09Z ON THE 19TH (TONIGHT).

&&

.MARINE...
18/300 AM PDT.

WINDS WILL LIKELY DIMINISH BELOW SMALL CRAFT ADVISORY LEVELS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS BY MID MORNING.
THERE IS A 20 TO 30 PERCENT CHANCE OF SMALL CRAFT ADVISORY CONDS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS AND THE WESTERN
PORTION OF THE SBA CHANNEL LATE THIS AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...DB
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES









000
FXUS66 KLOX 181133
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
435 AM PDT MON AUG 18 2014

UPDATED AVIATION SECTION

.SYNOPSIS...

AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&

.SHORT TERM (TODAY-WED)...
MARINE LAYER IS 1300 FEET AND PROBABLY A LITTLE LOWER NORTH OF POINT
CONCEPTION. THERE IS A 3 MB ONSHORE PUSH TO KDAG BUT ONLY A 1 MB
PUSH TO KBFL. THERE IS AN UPPER LOW OVER CRESCENT CITY BUT THE LIFT
ASSOC WITH THIS LOW IS NOT NEAR ENOUGH TO SOCAL TO HELP FORM MARINE
LAYER STRATUS. AS A RESULT CLOUDS HAVE BEEN SLOW TO FORM SOUTH OF
POINT CONCEPTION. THERE SHOULD BE SOME LOW CLOUDS ACROSS THE LA
COAST BUT THATS ABOUT IT. THE CENTRAL COAST AND SANTA YNEZ VLY A
CHOCK FULL OF LOW CLOUDS AND THERE IS EVEN SOME DENSE FOG. THE LOW
WILL MOVE CLOSE TO THE AREA TODAY AND THE FALLING HGTS AS WELL AS
INCREASING ONSHORE FLOW WILL KICK OFF A COOLING TREND OVER THE AREA.

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/1135Z
WIDESPREAD STRATUS ON THE CENTRAL COAST AND IN THE SANTA YNEZ VALLEY
THIS MORNING. EXPECT STRATUS TO FILL IN ACROSS COASTAL SECTIONS OF
L.A. AND VTU COUNTIES BY DAYBREAK. CONDS WILL BE MOSTLY IFR TO
LIFR...EXCEPT MOST LIKELY MVFR ACROSS THE L.A. COUNTY COAST. EXPECT
SKIES TO CLEAR BY MID OR LATE MORNING IN MOST AREAS. STRATUS SHOULD
BE MORE WIDESPREAD TONIGHT...AND WITH A DEEPENING MARINE
LAYER...EXPECT CLOUDS TO PUSH INTO THE L.A. COUNTY VLYS. CONDS
SHOULD BE MOSTLY IFR...EXCEPT MVFR ON THE L.A. COUNTY COASTAL
PLAIN...AND RIGHT NEAR THE THRESHOLD OF IFR/MVFR ACROSS CSTL
SECTIONS OF VTU AND SRN SBA COUNTIES.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20
PERCENT CHANCE THAT CONDS WILL REMAIN VFR THIS MORNING. THERE IS A
20 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 06Z ON THE 19TH
(TONIGHT).

KBUR...HIGH CONFIDENCE IN THE 12Z TAF. THERE IS A 20 PERCENT CHANCE
THAT CIGS TONIGHT WILL ARRIVE AS EARLY AS 09Z ON THE 19TH (TONIGHT).

&&

.MARINE...
18/300 AM PDT.

WINDS WILL LIKELY DIMINISH BELOW SMALL CRAFT ADVISORY LEVELS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS BY MID MORNING.
THERE IS A 20 TO 30 PERCENT CHANCE OF SMALL CRAFT ADVISORY CONDS
ACROSS THE SOUTHERN TWO THIRDS OF THE OUTER WATERS AND THE WESTERN
PORTION OF THE SBA CHANNEL LATE THIS AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...DB
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES










000
FXUS66 KLOX 181032
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
330 AM PDT MON AUG 18 2014

.SYNOPSIS...

AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&

.SHORT TERM (TODAY-WED)...
MARINE LAYER IS 1300 FEET AND PROBABLY A LITTLE LOWER NORTH OF POINT
CONCEPTION. THERE IS A 3 MB ONSHORE PUSH TO KDAG BUT ONLY A 1 MB
PUSH TO KBFL. THERE IS AN UPPER LOW OVER CRESCENT CITY BUT THE LIFT
ASSOC WITH THIS LOW IS NOT NEAR ENOUGH TO SOCAL TO HELP FORM MARINE
LAYER STRATUS. AS A RESULT CLOUDS HAVE BEEN SLOW TO FORM SOUTH OF
POINT CONCEPTION. THERE SHOULD BE SOME LOW CLOUDS ACROSS THE LA
COAST BUT THATS ABOUT IT. THE CENTRAL COAST AND SANTA YNEZ VLY A
CHOCK FULL OF LOW CLOUDS AND THERE IS EVEN SOME DENSE FOG. THE LOW
WILL MOVE CLOSE TO THE AREA TODAY AND THE FALLING HGTS AS WELL AS
INCREASING ONSHORE FLOW WILL KICK OFF A COOLING TREND OVER THE AREA.

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/0530Z

EXPECT WIDESPREAD STRATUS IN ALL COASTAL SECTIONS TONIGHT...WITH THE
POSSIBLE EXCEPTION OF THE S COAST OF SBA COUNTY. EXPECT MAINLY IFR
CONDS...WITH LIFR CONDS ON THE CENTRAL COAST. AT THIS POINT...EXPECT
THE VALLEYS TO STAY CLEAR...ALTHOUGH THERE IS A SLIGHT CHANCE OF IFR
CONDS FOR A COUPLE OF HOURS AROUND DAYBREAK. SKIES SHOULD CLEAR IN
MOST AREA BY MID TO LATE MORNING ON MON.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20 TO
30 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 09Z.

KBUR...HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 10 TO 20 PERCENT
CHANCE OF IFR TO LIFR CIGS BETWEEN 12Z AND 15Z.

&&

.MARINE...

18/900 PM PDT.

WINDS WILL LIKELY DIMINISH BELOW SMALL CRAFT ADVISORY LEVELS IN ALL
WATERS LATE TONIGHT...THEN THERE IS A 20 TO 30 PERCENT CHANCE OF
SMALL CRAFT ADVISORY CONDS ACROSS THE SOUTHERN TWO THIRDS OF THE
OUTER WATERS AND THE WESTERN PORTION OF THE SBA CHANNEL MON
AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...BRUNO
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES






000
FXUS66 KLOX 181032
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
330 AM PDT MON AUG 18 2014

.SYNOPSIS...

AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND THROUGH
THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD MOVE NORTH
FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF SHOWERS.

&&

.SHORT TERM (TODAY-WED)...
MARINE LAYER IS 1300 FEET AND PROBABLY A LITTLE LOWER NORTH OF POINT
CONCEPTION. THERE IS A 3 MB ONSHORE PUSH TO KDAG BUT ONLY A 1 MB
PUSH TO KBFL. THERE IS AN UPPER LOW OVER CRESCENT CITY BUT THE LIFT
ASSOC WITH THIS LOW IS NOT NEAR ENOUGH TO SOCAL TO HELP FORM MARINE
LAYER STRATUS. AS A RESULT CLOUDS HAVE BEEN SLOW TO FORM SOUTH OF
POINT CONCEPTION. THERE SHOULD BE SOME LOW CLOUDS ACROSS THE LA
COAST BUT THATS ABOUT IT. THE CENTRAL COAST AND SANTA YNEZ VLY A
CHOCK FULL OF LOW CLOUDS AND THERE IS EVEN SOME DENSE FOG. THE LOW
WILL MOVE CLOSE TO THE AREA TODAY AND THE FALLING HGTS AS WELL AS
INCREASING ONSHORE FLOW WILL KICK OFF A COOLING TREND OVER THE AREA.

BY TUESDAY MORNING THE UPPER LOW IS JUST TO THE WEST OF MONTERREY
BAY. THIS POSITION WILL BRING AMPLE LIFT TO SOCAL AND THE MARINE
LAYER SHOULD DEEPEN QUICKLY. MARINE LAYER STRATUS WILL DEVELOP AND
SHOULD SPREAD INTO ALL COASTS AND VLYS. THERE WILL BE ENOUGH LIFT TO
CREATE LOCAL DRIZZLE ESP NEAR THE FOOTHILLS. LOW CLOUDS WILL CLEAR
(PROBABLY SLOWLY) FROM MOST AREAS BUT MANY BEACHES WILL REMAIN
CLOUDY. MAX TEMPS WILL PLUNGE AND ALL AREAS WILL BE BELOW NORMAL.

THE UPPER LOW WILL BE RIGHT OVER THE SBA MTNS WEDNESDAY. THE DEEP
MARINE LAYER AND ATTENDANT STRATUS CLOUDS WILL CONTINUE ACROSS ALL
CSTS AND VLYS BUT THERE WILL NOT BE ENOUGH LIFT TO PRODUCE DRIZZLE.
THE COLD POOL WILL BE RIGHT OVERHEAD AND EVEN THOUGH THE ATMOSPHERE
WILL BE QUITE DRY THERE WILL STILL BE A SLIGHT CHC OF AN AFTERNOON
TSTMS OVER THE HIGHEST PEAKS. MAX TEMPS WILL CONTINUE TO BE MANY
DEGREES BLO NORMAL WITH HGTS FALLING TO AN UNCHARACTERISTIC 576 DM
OR 13 DM LESS THAN NORMAL.

.LONG TERM (THU-SUN)...
ALL MDLS ARE NOW IN BASIC AGREEMENT THAT THE UPPER LOW WILL SORT OF
WASH OUT AND SO CAL WILL BE UNDER A CULL AREA WITH HIGH PRESSURE TO
THE EAST AND WEST AND LOW PRESSURE TO THE NORTH AND SOUTH. THIS NEW
SOLN DOES NOT ALLOW FOR ANY MOISTURE TRANSPORT TO OUR AREA SO DRY
CONDITIONS ARE FORECAST AS IS A WARMING TREND THAT SHOULD BRING MAX
TEMPS TO ABOVE NORMAL BY SATURDAY.

STILL THIS IS A PATTERN THAT THE MDLS DO NOT HANDLE WELL AND WOULD
NOT BE SURPRISED IF THE MDL SOLN CHANGES OVER THE NEXT FEW DAYS.

&&

.AVIATION...

18/0530Z

EXPECT WIDESPREAD STRATUS IN ALL COASTAL SECTIONS TONIGHT...WITH THE
POSSIBLE EXCEPTION OF THE S COAST OF SBA COUNTY. EXPECT MAINLY IFR
CONDS...WITH LIFR CONDS ON THE CENTRAL COAST. AT THIS POINT...EXPECT
THE VALLEYS TO STAY CLEAR...ALTHOUGH THERE IS A SLIGHT CHANCE OF IFR
CONDS FOR A COUPLE OF HOURS AROUND DAYBREAK. SKIES SHOULD CLEAR IN
MOST AREA BY MID TO LATE MORNING ON MON.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20 TO
30 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 09Z.

KBUR...HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 10 TO 20 PERCENT
CHANCE OF IFR TO LIFR CIGS BETWEEN 12Z AND 15Z.

&&

.MARINE...

18/900 PM PDT.

WINDS WILL LIKELY DIMINISH BELOW SMALL CRAFT ADVISORY LEVELS IN ALL
WATERS LATE TONIGHT...THEN THERE IS A 20 TO 30 PERCENT CHANCE OF
SMALL CRAFT ADVISORY CONDS ACROSS THE SOUTHERN TWO THIRDS OF THE
OUTER WATERS AND THE WESTERN PORTION OF THE SBA CHANNEL MON
AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...RORKE
AVIATION/MARINE...BRUNO
SYNOPSIS...KAPLAN

WWW.WEATHER.GOV/LOSANGELES







000
FXUS66 KLOX 180522 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1025 PM PDT SUN AUG 17 2014

UPDATED AVIATION AND MARINE SECTIONS

.SYNOPSIS...

AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND
THROUGH THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD
MOVE NORTH FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF
SHOWERS.

&&

.SHORT TERM (TONIGHT-WEDNESDAY)...

IT WAS ANOTHER SCORCHER ACROSS THE INTERIOR PORTIONS OF THE FORECAST
AREA. IN FACT IT WAS A 2 TO 3 DEGREES WARMER THEN YESTERDAY FOR
VALLEY...LOWER LEVEL MOUNTAIN ELEVATIONS AND THE ANTELOPE VALLEY.
THERE WAS A FEW DEGREES OF COOLING ALONG THE CENTRAL COAST AND A FEW
DEGREES OF COOLING ACROSS PORTIONS OF THE LA COUNTY COAST. BOTH
WOODLAND HILLS AND SAUGUS REACHED 101 DEGREES...WHILE PASO ROBLES
AND MUCH OF THE ANTELOPE VALLEY REPORTED HIGHS OF 102 DEGREES TODAY.
THERE WAS ENOUGH INSTABILITY IN THE ATMOSPHERE OVER THE SAN GABRIEL
MOUNTAINS TODAY THAT A FEW PYROCUMULUS CLOUDS FORMED THIS AFTERNOON
FROM THE TECOLOTE FIRE THAT STARTED AROUND 230 PM. WINDS SHOULD BE
RELATIVELY WEAK OVERNIGHT AND SMOKE SHOULD SPREAD OVER THE SAN
GABRIEL MOUNTAINS AND INTO THE ANTELOPE VALLEY...AND POSSIBLY THE
SAN GABRIEL VALLEY.

LATEST FOG PRODUCT IMAGERY INDICATED LOW CLOUDS ALREADY PUSHING INTO
PORTIONS OF THE CENTRAL COAST...MAINLY SANTA BARBARA COUNTY...BUT
LOW CLOUDS AND FOG WILL SPREAD INLAND OVER THE NEXT FEW HOURS. FOR
AREAS S OF POINT CONCEPTION...A SIMILAR PATTERN TO THE PAST FEW
NIGHTS. THERE WERE SOME CLOUDS PUSHING ACROSS THE OUTER CHANNEL
ISLANDS...OTHERWISE SKIES WERE CLEAR. THE LATEST ACARS SOUNDING NEAR
LAX INDICATED A RELATIVELY STRONG INVERSION AROUND 800 FT DEEP THIS
EVE. HAVE BACKED OFF OF LOW CLOUDS MOVING WELL INTO THE SAN GABRIEL
VALLEY AND SAN FERNANDO VALLEY AS INVERSION REMAINS STRONG. LATEST
NAM-WRF DOES HINT AT A WEAK EDDY CIRCULATION ACROSS THE SO CAL BIGHT
AFTER MIDNIGHT WITH NORTH WINDS ACROSS SOUTHERN SBA COUNTY...FEELING
PRETTY CONFIDENT THAT LOW CLOUDS WILL BE LIMITED TO LOS
ANGELES/VENTURA COUNTY COASTAL AREAS AFTER MIDNIGHT...AND COULD
SPILL OVER INTO THE SAN GABRIEL VALLEY AROUND DAWN TOMORROW AS WELL
AS THE TOP OF THE CONEJO PASS IN NEWBURY PARK. BUT MOST VALLEYS
SHOULD REMAIN MOSTLY CLEAR ONE MORE NIGHT.

SYNOPTICALLY...AN UPPER LEVEL LOW AND ASSOCIATED TROUGH WAS LOCATED
JUST OFF THE COAST OF OREGON/WASHINGTON THIS EVE. AN UPPER LVL RIDGE
CONTINUED TO DOMINATE THE UPPER PATTERN OVER SO CAL. THE CUTOFF LOW
WILL CONTINUE TO JOG SOUTH JUST OFF THE COAST OF EUREKA CAL BY
MONDAY AFTERNOON PUSHING THE UPPER RIDGE FURTHER EAST. THIS WILL
TRANSLATE INTO STRONGER ONSHORE FLOW AND A DEEPER MARINE LAYER
ALLOWING FOR PLENTY OF LOW CLOUDS TO PUSH INTO VALLEY LOCATIONS.
EXPECT MOST INLAND AREAS TO LOWER 3 TO 6 DEGREES TOMORROW...WHILE A
COOLING TREND WILL CONTINUE ACROSS COASTAL AREAS AS WELL.

BY MONDAY NIGHT INTO TUESDAY MORNING...MODELS ARE CONSISTENT WITH
DROPPING THE UPPER LOW OVER THE CENTRAL COAST AND DOWN INTO SOUTHERN
CAL TUE EVE. AT THIS POINT IT LOOKS LIKE THE MAIN ISSUE WITH THIS
UPPER LOW WILL BE A DEEPER MARINE LAYER WHICH SHOULD BRING SOME
PATCHY DRIZZLE TO AREAS WEST OF THE MOUNTAINS BOTH TUE AND WED
MORNINGS. MID LEVEL MOISTURE WITH THIS UPPER LOW WILL BE LIMITED.
THERE WILL BE SOME MARGINAL INSTABILITY OVER THE VENTURA AND SBA
COUNTY MOUNTAINS...SO A FEW CU BUILDUPS WILL BE POSSIBLE...AND EVEN
AN ELEVATED SHOWER OR THUNDERSTORM. IF THIS DOES OCCUR...THE MAIN
ISSUE WILL BE DRY LIGHTNING AND GUSTY DOWNDRAFT WINDS. FOR NOW WILL
LEAVE THAT OUT OF THE FORECAST AND WAIT FOR FUTURE MODEL DATA FOR
BETTER CONFIDENCE.  THE MARINE LAYER STRATUS SHOULD REACH THE
COASTAL SLOPES OF THE MOUNTAINS AND THERE COULD BE A SLOW BURNOFF
ALONG THE COAST BOTH TUE AND WED. HIGH TEMPS WILL BE MUCH COOLER AS
WELL. MOST INLAND LOCATIONS WILL BE 6 TO 12 DEGREES COOLER WHILE
COASTAL AREAS WILL BE IN THE 70S.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (WEDNESDAY-SUNDAY)...

THE WEATHER PICTURE FROM THE MODELS PERSPECTIVE GETS A LITTLE
MORE MURKY FROM WEDNESDAY ON. MODEL SOLUTIONS STRUGGLE WITH THE
MOVEMENT OF A DEVELOPING TROPICAL FEATURE CURRENTLY ABOUT 600
MILES SOUTHWEST OF THE TIP OF BAJA CALIFORNIA. THE MODELS HAVE
GANGED UP INTO TWO DISTINCT CAMPS WITH THE NAM-WRF...ECMWF...AND
GEM SOLUTIONS FALLING CLOSELY INLINE IN ONE GROUP AND GFS
SOLUTIONS IN THE OTHER. IF 12Z AND 18Z NAM-WRF AND 12Z GEM/ECMWF
SOLUTIONS PLAY OUT...CONVECTIVE STORMS WILL LIKELY DEVELOP OVER
LOS ANGELES COUNTY ON WEDNESDAY AFTERNOON AND NIGHT...WHILE GFS
SOLUTIONS ARE MUCH SLOWER WITH THE TRANSPORT OF THE MOISTURE
NORTH. GEFS ENSEMBLE MEMBERS OFFER A WIDE SPREAD OF SOLUTIONS FOR
THE LATE WEEK WITH A COUPLE OF MEMBERS CLOSELY RESEMBLING THE
SOLUTIONS OF THE NAM-WRF...GEM...AND ECMWF SOLUTIONS. DUE TO
DISAGREEMENTS...THE FORECAST REMAINS DRY AT THIS TIME BUT TIME
SHOULD SOLVE THIS PROBLEM. WITH 18Z NAM-WRF SOLUTIONS REMAINING
CONSISTENT WITH 12Z RUNS AND FALLING INLINE WITH THE GEM AND ECMWF
SOLUTIONS...FUTURE SHIFTS MAY WISH TO FOLLOW THIS IDEA.

&&

.AVIATION...18/0530Z.
EXPECT WIDESPREAD STRATUS IN ALL COASTAL SECTIONS TONIGHT...WITH THE
POSSIBLE EXCEPTION OF THE S COAST OF SBA COUNTY. EXPECT MAINLY IFR
CONDS...WITH LIFR CONDS ON THE CENTRAL COAST. AT THIS POINT...EXPECT
THE VALLEYS TO STAY CLEAR...ALTHOUGH THERE IS A SLIGHT CHANCE OF IFR
CONDS FOR A COUPLE OF HOURS AROUND DAYBREAK. SKIES SHOULD CLEAR IN
MOST AREA BY MID TO LATE MORNING ON MON.

KLAX...MODERATE TO HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 20 TO
30 PERCENT CHANCE THAT CIGS WILL ARRIVE AS EARLY AS 09Z.

KBUR...HIGH CONFIDENCE IN THE 06Z TAF. THERE IS A 10 TO 20 PERCENT
CHANCE OF IFR TO LIFR CIGS BETWEEN 12Z AND 15Z.

&&

.MARINE...18/900 PM PDT.

WINDS WILL LIKELY DIMINISH BELOW SMALL CRAFT ADVISORY LEVELS IN ALL
WATERS LATE TONIGHT...THEN THERE IS A 20 TO 30 PERCENT CHANCE OF
SMALL CRAFT ADVISORY CONDS ACROSS THE SOUTHERN TWO THIRDS OF THE
OUTER WATERS AND THE WESTERN PORTION OF THE SBA CHANNEL MON
AFTERNOON AND EVENING.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/HALL
AVIATION..DB
MARINE...DB

WWW.WEATHER.GOV/LOSANGELES


















000
FXUS66 KLOX 180329 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
830 PM PDT SUN AUG 17 2014

.SYNOPSIS...

AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND
THROUGH THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD
MOVE NORTH FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF
SHOWERS.

&&

.SHORT TERM (TONIGHT-WEDNESDAY)...

IT WAS ANOTHER SCORCHER ACROSS THE INTERIOR PORTIONS OF THE FORECAST
AREA. IN FACT IT WAS A 2 TO 3 DEGREES WARMER THEN YESTERDAY FOR
VALLEY...LOWER LEVEL MOUNTAIN ELEVATIONS AND THE ANTELOPE VALLEY.
THERE WAS A FEW DEGREES OF COOLING ALONG THE CENTRAL COAST AND A FEW
DEGREES OF COOLING ACROSS PORTIONS OF THE LA COUNTY COAST. BOTH
WOODLAND HILLS AND SAUGUS REACHED 101 DEGREES...WHILE PASO ROBLES
AND MUCH OF THE ANTELOPE VALLEY REPORTED HIGHS OF 102 DEGREES TODAY.
THERE WAS ENOUGH INSTABILITY IN THE ATMOSPHERE OVER THE SAN GABRIEL
MOUNTAINS TODAY THAT A FEW PYROCUMULUS CLOUDS FORMED THIS AFTERNOON
FROM THE TECOLOTE FIRE THAT STARTED AROUND 230 PM. WINDS SHOULD BE
RELATIVELY WEAK OVERNIGHT AND SMOKE SHOULD SPREAD OVER THE SAN
GABRIEL MOUNTAINS AND INTO THE ANTELOPE VALLEY...AND POSSIBLY THE
SAN GABRIEL VALLEY.

LATEST FOG PRODUCT IMAGERY INDICATED LOW CLOUDS ALREADY PUSHING INTO
PORTIONS OF THE CENTRAL COAST...MAINLY SANTA BARBARA COUNTY...BUT
LOW CLOUDS AND FOG WILL SPREAD INLAND OVER THE NEXT FEW HOURS. FOR
AREAS S OF POINT CONCEPTION...A SIMILAR PATTERN TO THE PAST FEW
NIGHTS. THERE WERE SOME CLOUDS PUSHING ACROSS THE OUTER CHANNEL
ISLANDS...OTHERWISE SKIES WERE CLEAR. THE LATEST ACARS SOUNDING NEAR
LAX INDICATED A RELATIVELY STRONG INVERSION AROUND 800 FT DEEP THIS
EVE. HAVE BACKED OFF OF LOW CLOUDS MOVING WELL INTO THE SAN GABRIEL
VALLEY AND SAN FERNANDO VALLEY AS INVERSION REMAINS STRONG. LATEST
NAM-WRF DOES HINT AT A WEAK EDDY CIRCULATION ACROSS THE SO CAL BIGHT
AFTER MIDNIGHT WITH NORTH WINDS ACROSS SOUTHERN SBA COUNTY...FEELING
PRETTY CONFIDENT THAT LOW CLOUDS WILL BE LIMITED TO LOS
ANGELES/VENTURA COUNTY COASTAL AREAS AFTER MIDNIGHT...AND COULD
SPILL OVER INTO THE SAN GABRIEL VALLEY AROUND DAWN TOMORROW AS WELL
AS THE TOP OF THE CONEJO PASS IN NEWBURY PARK. BUT MOST VALLEYS
SHOULD REMAIN MOSTLY CLEAR ONE MORE NIGHT.

SYNOPTICALLY...AN UPPER LEVEL LOW AND ASSOCIATED TROUGH WAS LOCATED
JUST OFF THE COAST OF OREGON/WASHINGTON THIS EVE. AN UPPER LVL RIDGE
CONTINUED TO DOMINATE THE UPPER PATTERN OVER SO CAL. THE CUTOFF LOW
WILL CONTINUE TO JOG SOUTH JUST OFF THE COAST OF EUREKA CAL BY
MONDAY AFTERNOON PUSHING THE UPPER RIDGE FURTHER EAST. THIS WILL
TRANSLATE INTO STRONGER ONSHORE FLOW AND A DEEPER MARINE LAYER
ALLOWING FOR PLENTY OF LOW CLOUDS TO PUSH INTO VALLEY LOCATIONS.
EXPECT MOST INLAND AREAS TO LOWER 3 TO 6 DEGREES TOMORROW...WHILE A
COOLING TREND WILL CONTINUE ACROSS COASTAL AREAS AS WELL.

BY MONDAY NIGHT INTO TUESDAY MORNING...MODELS ARE CONSISTENT WITH
DROPPING THE UPPER LOW OVER THE CENTRAL COAST AND DOWN INTO SOUTHERN
CAL TUE EVE. AT THIS POINT IT LOOKS LIKE THE MAIN ISSUE WITH THIS
UPPER LOW WILL BE A DEEPER MARINE LAYER WHICH SHOULD BRING SOME
PATCHY DRIZZLE TO AREAS WEST OF THE MOUNTAINS BOTH TUE AND WED
MORNINGS. MID LEVEL MOISTURE WITH THIS UPPER LOW WILL BE LIMITED.
THERE WILL BE SOME MARGINAL INSTABILITY OVER THE VENTURA AND SBA
COUNTY MOUNTAINS...SO A FEW CU BUILDUPS WILL BE POSSIBLE...AND EVEN
AN ELEVATED SHOWER OR THUNDERSTORM. IF THIS DOES OCCUR...THE MAIN
ISSUE WILL BE DRY LIGHTNING AND GUSTY DOWNDRAFT WINDS. FOR NOW WILL
LEAVE THAT OUT OF THE FORECAST AND WAIT FOR FUTURE MODEL DATA FOR
BETTER CONFIDENCE.  THE MARINE LAYER STRATUS SHOULD REACH THE
COASTAL SLOPES OF THE MOUNTAINS AND THERE COULD BE A SLOW BURNOFF
ALONG THE COAST BOTH TUE AND WED. HIGH TEMPS WILL BE MUCH COOLER AS
WELL. MOST INLAND LOCATIONS WILL BE 6 TO 12 DEGREES COOLER WHILE
COASTAL AREAS WILL BE IN THE 70S.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (WEDNESDAY-SUNDAY)...

THE WEATHER PICTURE FROM THE MODELS PERSPECTIVE GETS A LITTLE
MORE MURKY FROM WEDNESDAY ON. MODEL SOLUTIONS STRUGGLE WITH THE
MOVEMENT OF A DEVELOPING TROPICAL FEATURE CURRENTLY ABOUT 600
MILES SOUTHWEST OF THE TIP OF BAJA CALIFORNIA. THE MODELS HAVE
GANGED UP INTO TWO DISTINCT CAMPS WITH THE NAM-WRF...ECMWF...AND
GEM SOLUTIONS FALLING CLOSELY INLINE IN ONE GROUP AND GFS
SOLUTIONS IN THE OTHER. IF 12Z AND 18Z NAM-WRF AND 12Z GEM/ECMWF
SOLUTIONS PLAY OUT...CONVECTIVE STORMS WILL LIKELY DEVELOP OVER
LOS ANGELES COUNTY ON WEDNESDAY AFTERNOON AND NIGHT...WHILE GFS
SOLUTIONS ARE MUCH SLOWER WITH THE TRANSPORT OF THE MOISTURE
NORTH. GEFS ENSEMBLE MEMBERS OFFER A WIDE SPREAD OF SOLUTIONS FOR
THE LATE WEEK WITH A COUPLE OF MEMBERS CLOSELY RESEMBLING THE
SOLUTIONS OF THE NAM-WRF...GEM...AND ECMWF SOLUTIONS. DUE TO
DISAGREEMENTS...THE FORECAST REMAINS DRY AT THIS TIME BUT TIME
SHOULD SOLVE THIS PROBLEM. WITH 18Z NAM-WRF SOLUTIONS REMAINING
CONSISTENT WITH 12Z RUNS AND FALLING INLINE WITH THE GEM AND ECMWF
SOLUTIONS...FUTURE SHIFTS MAY WISH TO FOLLOW THIS IDEA.

&&

.AVIATION...18/0015Z.
EXPECT WIDESPREAD STRATUS TO DEVELOP IN ALL COASTAL SECTIONS
TONIGHT...WITH THE POSSIBLE EXCEPTION OF THE S COAST OF SBA COUNTY.
EXPECT MAINLY IFR CONDS...WITH LIFR CONDS ON THE CENTRAL COAST. FOR
NOW...HAVE KEPT THE FORECAST OF LOW CLOUDS WITH IFR/LIFR CONDS
PUSHING INTO THE L.A. COUNTY VLYS FOR A FEW HOURS LATE TONIGHT/MON
MORNING...BUT CONFIDENCE IS LOW. SKIES SHOULD CLEAR IN MOST AREA BY
MID TO LATE MORNING ON MON.

KLAX...MODERATE CONFIDENCE IN 00Z TAF. THERE IS A 20 TO 30 PERCENT
CHANCE OF IFR CIGS BETWEEN 02Z AND 05Z....BEFORE THE MAIN STRATUS
ARRIVES SOMETIME BETWEEN 08Z AND 10Z.

KBUR...LOW CONFIDENCE IN 00Z TAF. THERE IS A 40 PERCENT CHANCE
THAT CONDS WILL REMAIN VFR THROUGH THE PD.

&&

.MARINE...17/200 PM.

SMALL CRAFT ADVISORY CONDITIONS WILL LIKELY REDEVELOP THIS AFTERNOON
IN THE VICINITY OF THE NORTHERN CHANNEL ISLANDS AND POINT CONCEPTION
AND PERSIST THROUGH MONDAY MORNING. THERE IS A CHANCE THE CONDITIONS
WILL SPREAD OVER THE WEST PORTION OF THE SANTA BARBARA CHANNEL THIS
EVENING. SMALL CRAFT ADVISORY CONDITIONS MAY REDEVELOP MONDAY
EVENING IN THE WEST PORTION OF SANTA BARBARA CHANNEL AND WESTWARD
FROM SANTA CRUZ ISLAND OUT TO 60 NM. OTHERWISE SMALL CRAFT ADVISORY
CONDITIONS ARE NOT EXPECTED THEREAFTER OVER THE AREA. A SOUTH SWELL
ORIGINATING FROM THE TROPICS WILL SUBSIDE THIS AFTERNOON AND BUILD
AGAIN THURSDAY. A LONGER PERIOD SOUTH SWELL ORIGINATING IN THE
SOUTHERN HEMISPHERE IS EXPECTED TO ARRIVE THIS AFTERNOON AND THEN
PERSIST THROUGH WEDNESDAY. SHORT PERIOD LOCALLY GENERATED WEST AND
NORTHWEST SWELL WILL BUILD TONIGHT AND THEN PERSIST THROUGH THE
PERIOD.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/HALL
AVIATION..DB
MARINE...30

WWW.WEATHER.GOV/LOSANGELES















000
FXUS66 KLOX 180329 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
830 PM PDT SUN AUG 17 2014

.SYNOPSIS...

AN APPROACHING TROUGH OF LOW PRESSURE WILL INCREASE ONSHORE
FLOW...DEEPEN THE MARINE LAYER...AND BRING A COOLING TREND
THROUGH THURSDAY. IT IS POSSIBLE THAT SUBTROPICAL MOISTURE COULD
MOVE NORTH FOR LATE WEEK AND BRING HUMID CONDITIONS AND CHANCE OF
SHOWERS.

&&

.SHORT TERM (TONIGHT-WEDNESDAY)...

IT WAS ANOTHER SCORCHER ACROSS THE INTERIOR PORTIONS OF THE FORECAST
AREA. IN FACT IT WAS A 2 TO 3 DEGREES WARMER THEN YESTERDAY FOR
VALLEY...LOWER LEVEL MOUNTAIN ELEVATIONS AND THE ANTELOPE VALLEY.
THERE WAS A FEW DEGREES OF COOLING ALONG THE CENTRAL COAST AND A FEW
DEGREES OF COOLING ACROSS PORTIONS OF THE LA COUNTY COAST. BOTH
WOODLAND HILLS AND SAUGUS REACHED 101 DEGREES...WHILE PASO ROBLES
AND MUCH OF THE ANTELOPE VALLEY REPORTED HIGHS OF 102 DEGREES TODAY.
THERE WAS ENOUGH INSTABILITY IN THE ATMOSPHERE OVER THE SAN GABRIEL
MOUNTAINS TODAY THAT A FEW PYROCUMULUS CLOUDS FORMED THIS AFTERNOON
FROM THE TECOLOTE FIRE THAT STARTED AROUND 230 PM. WINDS SHOULD BE
RELATIVELY WEAK OVERNIGHT AND SMOKE SHOULD SPREAD OVER THE SAN
GABRIEL MOUNTAINS AND INTO THE ANTELOPE VALLEY...AND POSSIBLY THE
SAN GABRIEL VALLEY.

LATEST FOG PRODUCT IMAGERY INDICATED LOW CLOUDS ALREADY PUSHING INTO
PORTIONS OF THE CENTRAL COAST...MAINLY SANTA BARBARA COUNTY...BUT
LOW CLOUDS AND FOG WILL SPREAD INLAND OVER THE NEXT FEW HOURS. FOR
AREAS S OF POINT CONCEPTION...A SIMILAR PATTERN TO THE PAST FEW
NIGHTS. THERE WERE SOME CLOUDS PUSHING ACROSS THE OUTER CHANNEL
ISLANDS...OTHERWISE SKIES WERE CLEAR. THE LATEST ACARS SOUNDING NEAR
LAX INDICATED A RELATIVELY STRONG INVERSION AROUND 800 FT DEEP THIS
EVE. HAVE BACKED OFF OF LOW CLOUDS MOVING WELL INTO THE SAN GABRIEL
VALLEY AND SAN FERNANDO VALLEY AS INVERSION REMAINS STRONG. LATEST
NAM-WRF DOES HINT AT A WEAK EDDY CIRCULATION ACROSS THE SO CAL BIGHT
AFTER MIDNIGHT WITH NORTH WINDS ACROSS SOUTHERN SBA COUNTY...FEELING
PRETTY CONFIDENT THAT LOW CLOUDS WILL BE LIMITED TO LOS
ANGELES/VENTURA COUNTY COASTAL AREAS AFTER MIDNIGHT...AND COULD
SPILL OVER INTO THE SAN GABRIEL VALLEY AROUND DAWN TOMORROW AS WELL
AS THE TOP OF THE CONEJO PASS IN NEWBURY PARK. BUT MOST VALLEYS
SHOULD REMAIN MOSTLY CLEAR ONE MORE NIGHT.

SYNOPTICALLY...AN UPPER LEVEL LOW AND ASSOCIATED TROUGH WAS LOCATED
JUST OFF THE COAST OF OREGON/WASHINGTON THIS EVE. AN UPPER LVL RIDGE
CONTINUED TO DOMINATE THE UPPER PATTERN OVER SO CAL. THE CUTOFF LOW
WILL CONTINUE TO JOG SOUTH JUST OFF THE COAST OF EUREKA CAL BY
MONDAY AFTERNOON PUSHING THE UPPER RIDGE FURTHER EAST. THIS WILL
TRANSLATE INTO STRONGER ONSHORE FLOW AND A DEEPER MARINE LAYER
ALLOWING FOR PLENTY OF LOW CLOUDS TO PUSH INTO VALLEY LOCATIONS.
EXPECT MOST INLAND AREAS TO LOWER 3 TO 6 DEGREES TOMORROW...WHILE A
COOLING TREND WILL CONTINUE ACROSS COASTAL AREAS AS WELL.

BY MONDAY NIGHT INTO TUESDAY MORNING...MODELS ARE CONSISTENT WITH
DROPPING THE UPPER LOW OVER THE CENTRAL COAST AND DOWN INTO SOUTHERN
CAL TUE EVE. AT THIS POINT IT LOOKS LIKE THE MAIN ISSUE WITH THIS
UPPER LOW WILL BE A DEEPER MARINE LAYER WHICH SHOULD BRING SOME
PATCHY DRIZZLE TO AREAS WEST OF THE MOUNTAINS BOTH TUE AND WED
MORNINGS. MID LEVEL MOISTURE WITH THIS UPPER LOW WILL BE LIMITED.
THERE WILL BE SOME MARGINAL INSTABILITY OVER THE VENTURA AND SBA
COUNTY MOUNTAINS...SO A FEW CU BUILDUPS WILL BE POSSIBLE...AND EVEN
AN ELEVATED SHOWER OR THUNDERSTORM. IF THIS DOES OCCUR...THE MAIN
ISSUE WILL BE DRY LIGHTNING AND GUSTY DOWNDRAFT WINDS. FOR NOW WILL
LEAVE THAT OUT OF THE FORECAST AND WAIT FOR FUTURE MODEL DATA FOR
BETTER CONFIDENCE.  THE MARINE LAYER STRATUS SHOULD REACH THE
COASTAL SLOPES OF THE MOUNTAINS AND THERE COULD BE A SLOW BURNOFF
ALONG THE COAST BOTH TUE AND WED. HIGH TEMPS WILL BE MUCH COOLER AS
WELL. MOST INLAND LOCATIONS WILL BE 6 TO 12 DEGREES COOLER WHILE
COASTAL AREAS WILL BE IN THE 70S.

***FROM PREVIOUS DISCUSSION***

.LONG TERM (WEDNESDAY-SUNDAY)...

THE WEATHER PICTURE FROM THE MODELS PERSPECTIVE GETS A LITTLE
MORE MURKY FROM WEDNESDAY ON. MODEL SOLUTIONS STRUGGLE WITH THE
MOVEMENT OF A DEVELOPING TROPICAL FEATURE CURRENTLY ABOUT 600
MILES SOUTHWEST OF THE TIP OF BAJA CALIFORNIA. THE MODELS HAVE
GANGED UP INTO TWO DISTINCT CAMPS WITH THE NAM-WRF...ECMWF...AND
GEM SOLUTIONS FALLING CLOSELY INLINE IN ONE GROUP AND GFS
SOLUTIONS IN THE OTHER. IF 12Z AND 18Z NAM-WRF AND 12Z GEM/ECMWF
SOLUTIONS PLAY OUT...CONVECTIVE STORMS WILL LIKELY DEVELOP OVER
LOS ANGELES COUNTY ON WEDNESDAY AFTERNOON AND NIGHT...WHILE GFS
SOLUTIONS ARE MUCH SLOWER WITH THE TRANSPORT OF THE MOISTURE
NORTH. GEFS ENSEMBLE MEMBERS OFFER A WIDE SPREAD OF SOLUTIONS FOR
THE LATE WEEK WITH A COUPLE OF MEMBERS CLOSELY RESEMBLING THE
SOLUTIONS OF THE NAM-WRF...GEM...AND ECMWF SOLUTIONS. DUE TO
DISAGREEMENTS...THE FORECAST REMAINS DRY AT THIS TIME BUT TIME
SHOULD SOLVE THIS PROBLEM. WITH 18Z NAM-WRF SOLUTIONS REMAINING
CONSISTENT WITH 12Z RUNS AND FALLING INLINE WITH THE GEM AND ECMWF
SOLUTIONS...FUTURE SHIFTS MAY WISH TO FOLLOW THIS IDEA.

&&

.AVIATION...18/0015Z.
EXPECT WIDESPREAD STRATUS TO DEVELOP IN ALL COASTAL SECTIONS
TONIGHT...WITH THE POSSIBLE EXCEPTION OF THE S COAST OF SBA COUNTY.
EXPECT MAINLY IFR CONDS...WITH LIFR CONDS ON THE CENTRAL COAST. FOR
NOW...HAVE KEPT THE FORECAST OF LOW CLOUDS WITH IFR/LIFR CONDS
PUSHING INTO THE L.A. COUNTY VLYS FOR A FEW HOURS LATE TONIGHT/MON
MORNING...BUT CONFIDENCE IS LOW. SKIES SHOULD CLEAR IN MOST AREA BY
MID TO LATE MORNING ON MON.

KLAX...MODERATE CONFIDENCE IN 00Z TAF. THERE IS A 20 TO 30 PERCENT
CHANCE OF IFR CIGS BETWEEN 02Z AND 05Z....BEFORE THE MAIN STRATUS
ARRIVES SOMETIME BETWEEN 08Z AND 10Z.

KBUR...LOW CONFIDENCE IN 00Z TAF. THERE IS A 40 PERCENT CHANCE
THAT CONDS WILL REMAIN VFR THROUGH THE PD.

&&

.MARINE...17/200 PM.

SMALL CRAFT ADVISORY CONDITIONS WILL LIKELY REDEVELOP THIS AFTERNOON
IN THE VICINITY OF THE NORTHERN CHANNEL ISLANDS AND POINT CONCEPTION
AND PERSIST THROUGH MONDAY MORNING. THERE IS A CHANCE THE CONDITIONS
WILL SPREAD OVER THE WEST PORTION OF THE SANTA BARBARA CHANNEL THIS
EVENING. SMALL CRAFT ADVISORY CONDITIONS MAY REDEVELOP MONDAY
EVENING IN THE WEST PORTION OF SANTA BARBARA CHANNEL AND WESTWARD
FROM SANTA CRUZ ISLAND OUT TO 60 NM. OTHERWISE SMALL CRAFT ADVISORY
CONDITIONS ARE NOT EXPECTED THEREAFTER OVER THE AREA. A SOUTH SWELL
ORIGINATING FROM THE TROPICS WILL SUBSIDE THIS AFTERNOON AND BUILD
AGAIN THURSDAY. A LONGER PERIOD SOUTH SWELL ORIGINATING IN THE
SOUTHERN HEMISPHERE IS EXPECTED TO ARRIVE THIS AFTERNOON AND THEN
PERSIST THROUGH WEDNESDAY. SHORT PERIOD LOCALLY GENERATED WEST AND
NORTHWEST SWELL WILL BUILD TONIGHT AND THEN PERSIST THROUGH THE
PERIOD.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/HALL
AVIATION..DB
MARINE...30

WWW.WEATHER.GOV/LOSANGELES














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