679 
FXUS66 KLOX 172159
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
200 PM PST SUN JAN 17 2010

.SYNOPSIS...A SERIES OF POWERFUL PACIFIC STORMS WILL BRING 
SIGNIFICANT RAIN...SNOW...PERIODS OF THUNDERSTORMS AND SOME VERY 
GUSTY WINDS AT TIMES TO THE AREA THROUGHOUT THE WEEK.    

&&

.SHORT TERM (TODAY-WED)...LATEST RADAR SHOWS SCATTERED LIGHT
SHOWERS CURRENTLY MOVING THROUGH THE AREA...WHICH IS A PRECURSOR
TO THE VERY WET WEEK AHEAD. THIS SHOWER ACTIVITY WILL CONTINUE
THROUGH THE NIGHT...BEFORE THE FIRST STORMS STARTS MOVING IN MONDAY 
MORNING. THROUGH TONIGHT...SNOW LEVELS WILL REMAIN ABOVE 7000 FEET
SO ONLY THE HIGHEST PEAKS WILL SEE ANY APPRECIABLE ACCUMULATION.

ON MONDAY...THE FIRST SYSTEM WILL BEGIN TO MOVE ON THROUGH THE AREA.
AT THIS TIME...ALL THE NECESSARY INGREDIENTS ARE THERE FOR SOME 
SIGNIFICANT RAINFALL THROUGH TUESDAY SUCH AS GOOD SOUTHERLY FLOW
AND DECENT SUBTROPICAL MOISTURE TAP (PWATS AROUND 1.2"). ALSO...
THERE WILL BE SOME GOOD INSTABILITY THAT MOVES INTO THE AREA
MONDAY AFTERNOON AND EVENING...WHICH SHOULD PRODUCE SOME EMBEDDED
THUNDERSTORMS THROUGH MONDAY EVENING. TOTAL RAINFALL AMOUNTS WITH
THIS FIRST SYSTEM SHOULD GENERALLY RANGE 1-3" FOR COAST AND 3-6" IN 
THE MOUNTAINS. GIVEN THE RAINFALL AMOUNTS AND POTENTIAL INTENSE 
RAINFALL RATES WITH CONVECTION...MUD/DEBRIS FLOWS WILL BE A GREAT
CONCERN. WILL ISSUE FLASH FLOOD WATCH FOR THE BURN AREAS WITH THE 
AFTERNOON PACKAGE. AS FOR SNOW LEVELS...EXPECT THEM TO REMAIN ABOVE
7000 FEET THROUGH MONDAY EVENING...BEFORE DROPPING TO AROUND 5000 
FEET BY TUESDAY MORNING. WILL ISSUE WINTER STORM WARNING WITH 
AFTERNOON PACKAGE...INDICATING MOST SIGNIFICANT SNOWFALL ABOVE
7000 FEET. ALONG WITH THE PRECIP...STRONG SOUTHERLY WINDS WILL
ACCOMPANY THE STORM...PRODUCING WARNING LEVEL WIND GUSTS ACROSS 
SLO/SBA COUNTIES. WILL ISSUE A HIGH WIND WARNING FOR THESE AREAS 
WITH AFTERNOON PACKAGE.

THE NEXT SYSTEM WILL APPROACH THE AREA ON TUESDAY AFTERNOON...
BRINGING MORE RAINFALL TO THE AREA THROUGH WEDNESDAY MORNING. 
RAINFALL AMOUNTS WITH THIS SYSTEM WILL BE LESS THAN MONDAY'S STORM. 
HOWEVER...SNOW LEVELS WILL BE LOWER...SO SOME SIGNIFICANT SNOWFALL
CAN BE EXPECTED AT LOWER ELEVATIONS. 

BY WEDNESDAY AFTERNOON...THE THIRD AND MOST SIGNIFICANT STORM OF 
THE WEEK WILL BEGIN TO MOVE INTO THE AREA. HEAVY RAINFALL WILL 
DEVELOP WEDNESDAY AFTERNOON AND CONTINUE THROUGH THE EVENING. 
WITH THIS THIRD SYSTEM...STRONG SOUTHERLY FLOW WILL BUMP UP THE
SNOW LEVELS SOMEWHAT THROUGH WEDNESDAY NIGHT (AROUND 5500 FEET).
SO...HEAVY SNOWFALL WILL CONTINUE IN THE MOUNTAINS. IN ADDITION
FLASH FLOOD AND HIGH WIND PRODUCTS WILL LIKELY BE COMMON.

.LONG TERM (THU-SUN)...ON THURSDAY...THE HEAVY RAIN WILL CONTINUE
AS STRONG SOUTH/SOUTHWEST FLOW AND PWATS AROUND 1.40" CONTINUE 
ACROSS THE AREA. THE ONE INTERESTING NOTE WITH THURSDAY WILL BE
THE FACT THAT A 170+ KNOT JET MOVES OVER THE AREA. THIS SHOULD 
PROVIDE SOME EXTRA DYNAMICS TO PRODUCE VERY INTENSE RAINFALL AND 
THUNDERSTORMS ACROSS THE AREA. SNOW LEVELS WITH THIS SYSTEM WILL
REMAIN AROUND 5500 FEET. 

FOR FRIDAY THROUGH SUNDAY...MODELS ARE ALL OVER THE PLACE WITH 
THEIR SOLUTIONS. AT THIS TIME...IT STILL LOOKS RATHER UNSETTLED.
SO...WILL CONTINUE WITH MENTION OF PRECIPITATION THROUGH THE 
PERIOD...ALTHOUGH THE PRECIP WILL BE SHOWERY IN NATURE AND MUCH
LESS THAN OBSERVED DURING THE MIDDLE OF THE WEEK.

&&

.AVIATION...17/1800.

A MID/UPPER LEVEL TROUGH OF LOW PRESSURE UPSTREAM AND EXTENDING OVER 
THE AREA WILL PERSIST. STRONG AND MOIST UPPER LEVEL WEST AND 
SOUTHWEST WINDS WILL PREVAIL WHILE MID LEVEL MOIST AND LIGHT WEST 
WINDS BECOME STRONG SOUTHWEST AFTER 18/18Z. FREEZING LEVEL WAS 
AROUND 11KFT AND WILL DESCEND TO AROUND 7.5KFT BY 18/12Z. WEAK 
ONSHORE PRESSURE GRADIENT WILL BECOME STRONG SOUTH BY 18/18Z. THERE 
IS A CHANCE OF THUNDERSTORMS...WITH TOPS AROUND 35KFT...WITHIN A 
FAST APPROACHING AND STRENGTHENING FRONTAL SYSTEM AFTER 18/18Z. 

KLAX...IT IS LIKELY CIGS WILL DESCEND TO 027 WITH LIGHT SHOWERS BY 
17/20Z THE DESCEND TO AROUND 015 BY 18/08Z...THERE IS A CHANCE CIGS 
WILL DESCEND TO 010 WITH 3SM VSBY 18/14Z...OTHERWISE IT IS LIKELY 
CIGS WILL PERSIST BETWEEN 010-020. IT IS VERY LIKELY MODERATE AND 
GUSTY SOUTHEAST LOW LEVEL WINDS WILL DEVELOP BY 18/17Z.    

KBUR...IT IS VERY LIKELY CIGS 019 WILL BECOME SCT EARLY...THEN LIGHT 
SHOWERS WILL MOVE SOUTHEAST OVER THE AREA BY 17/20Z. RAIN WILL 
LIKELY BECOME STEADY WITH GRADUALLY DESCENDING CIGS TO 020 BY 
18/09Z.

VIRTUALLY CERTAIN - 95-100%
VERY LIKELY       - 80-95%
LIKELY            - 60-80%
CHANCE            - 30-60%
VERY UNLIKELY     - 20% OR LESS

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING (SEE LAXWSWLOX).
HIGH WIND WARNING (SEE LAXNPWLOX).
FLOOD WATCH (SEE LAXFFALOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
GALE WARNING (SEE LAXMWWLOX).
HIGH RIP CURRENT (SEE LAXSRFLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

$$

PUBLIC...THOMPSON
AVIATION...30
SYNOPSIS...BARTLING

WWW.WEATHER.GOV/LOSANGELES

822 
FXUS66 KLOX 172218
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
200 PM PST SUN JAN 17 2010

.SYNOPSIS...A SERIES OF POWERFUL PACIFIC STORMS WILL BRING 
SIGNIFICANT RAIN...SNOW...PERIODS OF THUNDERSTORMS AND SOME VERY 
GUSTY WINDS AT TIMES TO THE AREA THROUGHOUT THE WEEK.    

&&

.SHORT TERM (TODAY-WED)...LATEST RADAR SHOWS SCATTERED LIGHT
SHOWERS CURRENTLY MOVING THROUGH THE AREA...WHICH IS A PRECURSOR
TO THE VERY WET WEEK AHEAD. THIS SHOWER ACTIVITY WILL CONTINUE
THROUGH THE NIGHT...BEFORE THE FIRST STORMS STARTS MOVING IN MONDAY 
MORNING. THROUGH TONIGHT...SNOW LEVELS WILL REMAIN ABOVE 7000 FEET
SO ONLY THE HIGHEST PEAKS WILL SEE ANY APPRECIABLE ACCUMULATION.

ON MONDAY...THE FIRST SYSTEM WILL BEGIN TO MOVE ON THROUGH THE AREA.
AT THIS TIME...ALL THE NECESSARY INGREDIENTS ARE THERE FOR SOME 
SIGNIFICANT RAINFALL THROUGH TUESDAY SUCH AS GOOD SOUTHERLY FLOW
AND DECENT SUBTROPICAL MOISTURE TAP (PWATS AROUND 1.2"). ALSO...
THERE WILL BE SOME GOOD INSTABILITY THAT MOVES INTO THE AREA
MONDAY AFTERNOON AND EVENING...WHICH SHOULD PRODUCE SOME EMBEDDED
THUNDERSTORMS THROUGH MONDAY EVENING. TOTAL RAINFALL AMOUNTS WITH
THIS FIRST SYSTEM SHOULD GENERALLY RANGE 1-3" FOR COAST AND 3-6" IN 
THE MOUNTAINS. GIVEN THE RAINFALL AMOUNTS AND POTENTIAL INTENSE 
RAINFALL RATES WITH CONVECTION...MUD/DEBRIS FLOWS WILL BE A GREAT
CONCERN. WILL ISSUE FLASH FLOOD WATCH FOR THE BURN AREAS WITH THE 
AFTERNOON PACKAGE. AS FOR SNOW LEVELS...EXPECT THEM TO REMAIN ABOVE
7000 FEET THROUGH MONDAY EVENING...BEFORE DROPPING TO AROUND 5000 
FEET BY TUESDAY MORNING. WILL ISSUE WINTER STORM WARNING WITH 
AFTERNOON PACKAGE...INDICATING MOST SIGNIFICANT SNOWFALL ABOVE
7000 FEET. ALONG WITH THE PRECIP...STRONG SOUTHERLY WINDS WILL
ACCOMPANY THE STORM...PRODUCING WARNING LEVEL WIND GUSTS ACROSS 
SLO/SBA COUNTIES. WILL ISSUE A HIGH WIND WARNING FOR THESE AREAS 
WITH AFTERNOON PACKAGE.

THE NEXT SYSTEM WILL APPROACH THE AREA ON TUESDAY AFTERNOON...
BRINGING MORE RAINFALL TO THE AREA THROUGH WEDNESDAY MORNING. 
RAINFALL AMOUNTS WITH THIS SYSTEM WILL BE LESS THAN MONDAY'S STORM. 
HOWEVER...SNOW LEVELS WILL BE LOWER...SO SOME SIGNIFICANT SNOWFALL
CAN BE EXPECTED AT LOWER ELEVATIONS. 

BY WEDNESDAY AFTERNOON...THE THIRD AND MOST SIGNIFICANT STORM OF 
THE WEEK WILL BEGIN TO MOVE INTO THE AREA. HEAVY RAINFALL WILL 
DEVELOP WEDNESDAY AFTERNOON AND CONTINUE THROUGH THE EVENING. 
WITH THIS THIRD SYSTEM...STRONG SOUTHERLY FLOW WILL BUMP UP THE
SNOW LEVELS SOMEWHAT THROUGH WEDNESDAY NIGHT (AROUND 5500 FEET).
SO...HEAVY SNOWFALL WILL CONTINUE IN THE MOUNTAINS. IN ADDITION
FLASH FLOOD AND HIGH WIND PRODUCTS WILL LIKELY BE COMMON.

.LONG TERM (THU-SUN)...ON THURSDAY...THE HEAVY RAIN WILL CONTINUE
AS STRONG SOUTH/SOUTHWEST FLOW AND PWATS AROUND 1.40" CONTINUE 
ACROSS THE AREA. THE ONE INTERESTING NOTE WITH THURSDAY WILL BE
THE FACT THAT A 170+ KNOT JET MOVES OVER THE AREA. THIS SHOULD 
PROVIDE SOME EXTRA DYNAMICS TO PRODUCE VERY INTENSE RAINFALL AND 
THUNDERSTORMS ACROSS THE AREA. SNOW LEVELS WITH THIS SYSTEM WILL
REMAIN AROUND 5500 FEET. 

FOR FRIDAY THROUGH SUNDAY...MODELS ARE ALL OVER THE PLACE WITH 
THEIR SOLUTIONS. AT THIS TIME...IT STILL LOOKS RATHER UNSETTLED.
SO...WILL CONTINUE WITH MENTION OF PRECIPITATION THROUGH THE 
PERIOD...ALTHOUGH THE PRECIP WILL BE SHOWERY IN NATURE AND MUCH
LESS THAN OBSERVED DURING THE MIDDLE OF THE WEEK.

&&

.AVIATION...17/1800.

A MID/UPPER LEVEL TROUGH OF LOW PRESSURE UPSTREAM AND EXTENDING OVER 
THE AREA WILL PERSIST. STRONG AND MOIST UPPER LEVEL WEST AND 
SOUTHWEST WINDS WILL PREVAIL WHILE MID LEVEL MOIST AND LIGHT WEST 
WINDS BECOME STRONG SOUTHWEST AFTER 18/18Z. FREEZING LEVEL WAS 
AROUND 11KFT AND WILL DESCEND TO AROUND 7.5KFT BY 18/12Z. WEAK 
ONSHORE PRESSURE GRADIENT WILL BECOME STRONG SOUTH BY 18/18Z. THERE 
IS A CHANCE OF THUNDERSTORMS...WITH TOPS AROUND 35KFT...WITHIN A 
FAST APPROACHING AND STRENGTHENING FRONTAL SYSTEM AFTER 18/18Z. 

KLAX...IT IS LIKELY CIGS WILL DESCEND TO 027 WITH LIGHT SHOWERS BY 
17/20Z THE DESCEND TO AROUND 015 BY 18/08Z...THERE IS A CHANCE CIGS 
WILL DESCEND TO 010 WITH 3SM VSBY 18/14Z...OTHERWISE IT IS LIKELY 
CIGS WILL PERSIST BETWEEN 010-020. IT IS VERY LIKELY MODERATE AND 
GUSTY SOUTHEAST LOW LEVEL WINDS WILL DEVELOP BY 18/17Z.    

KBUR...IT IS VERY LIKELY CIGS 019 WILL BECOME SCT EARLY...THEN LIGHT 
SHOWERS WILL MOVE SOUTHEAST OVER THE AREA BY 17/20Z. RAIN WILL 
LIKELY BECOME STEADY WITH GRADUALLY DESCENDING CIGS TO 020 BY 
18/09Z.

VIRTUALLY CERTAIN - 95-100%
VERY LIKELY       - 80-95%
LIKELY            - 60-80%
CHANCE            - 30-60%
VERY UNLIKELY     - 20% OR LESS

&&

.MARINE...A SERIES OF STORMS WILL DEVELOP AND STRENGTHEN OVER THE 
CENTRAL AND EASTERN PACIFIC AND MOVE EAST OVER THE COASTAL WATERS 
THROUGH THU. GALE FORCE WINDS ARE EXPECTED MONDAY AND POSSIBLY 
PERSISTING THROUGH TUESDAY AND THEN THERE IS A CHANCE GALE FORCE 
WIND CONDITIONS WILL REDEVELOP WEDNESDAY. A PERSISTENT WEST TO EAST 
ORIENTED FETCH OVER THE CENTRAL AND EASTERN PACIFIC ALONG 35 N WILL 
LIKELY GENERATE SEAS AROUND 40 FEET MONDAY THROUGH TUESDAY. SEAS WILL BUILD 
SHARPLY MONDAY AFTERNOON NEAR SHORE AS GALE FORCE WINDS DEVELOP AND 
WILL RANGE 5 TO 10 FEET IN THE SANTA MONICA AND SANTA BARBARA BASINS 
TO 14 TO 18 FEET ELSEWHERE AND CONTINUE BUILDING THROUGH WEDNESDAY 
AS SWELLS FROM THE DISTANCE FETCH ARRIVE. SEAS WILL LIKELY BUILD TO 
9 TO 13 FEET IN THE SANTA MONICA AND SANTA BARBARA BASINS TO 18 TO 
26 FEET ELSEWHERE WEDNESDAY NIGHT.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING (SEE LAXWSWLOX).
HIGH WIND WARNING (SEE LAXNPWLOX).
FLOOD WATCH (SEE LAXFFALOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
GALE WARNING (SEE LAXMWWLOX).
HIGH RIP CURRENT (SEE LAXSRFLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

$$

PUBLIC...THOMPSON
AVIATION...30
SYNOPSIS...BARTLING

WWW.WEATHER.GOV/LOSANGELES