More Weather on the Way

FXUS66 KLOX 042022

AFDLOX



SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
120 PM PDT WED MAY 4 2005

.SHORT TERM...

WELL DEFINED BAROCLINIC LEAF CLOUD PATTERN EVIDENT WITH SHORTWAVE TROUGH MOVING EAST FROM NEAR 31N/129W IS ALREADY SPREADING LIGHT RAIN NORTHEAST INTO THE COASTAL WATERS OFF OF THE CENTRAL COAST. MODELS AGREE ON MOISTURE DEEPENING...UPPER LEVEL DIVERGENCE INCREASING AND MID-LEVEL OMEGA FIELDS INCREASING OVER SOCAL IN ADVANCE OF UPPER LEVEL TROUGH AXIS MOVING TOWARD THE AREA TONIGHT. SOUTHWESTERLY FLOW ALSO INCREASES...BUT NOT TO AN ALARMING LEVEL. SO THERE WILL SOME OROGRAPHIC ENHANCEMENT OF RAINFALL...BUT EXCESSIVE AMOUNTS ARE NOT ANTICIPATED. CURRENT TIMING LOOKS TO BRING RAIN LIKELY TO THE CENTRAL COAST THIS EVENING WITH SLIGHT CHANCES DOWN TO LA COUNTY. RAIN PROBABILITY INCREASES OVERNIGHT TO CATEGORICAL NORTH OF POINT CONCEPTION AND LIKELY TO LA COUNTY.

SURFACE COLD FRONT WILL APPROACH THE CENTRAL COAST LATE TONIGHT...THEN MOSEY SOUTHEAST AND THROUGH LA COUNTY BY LATE AFTERNOON. A BAND OF HEAVIER RAIN IS LIKELY ALONG THE FRONT...AND AS LAPSE RATES STEEPEN WITH COOLER AIR ALOFT MOVING OVERHEAD THURSDAY...THERE WILL BE A SLIGHT CHC OF THUNDERSTORMS. LOOKS LIKE THE PERIOD OF HEAVIEST AND STEADIEST RAIN WILL BE 06Z TO 15Z NORTH OF POINT CONCEPTION...09Z TO 18Z IN SANTA BARBARA COUNTY...AND 12Z TO 21Z VENTURA AND LOS ANGELES COUNTIES. AFTER THESE TIME FRAMES AND BEHIND THE FRONT...THERE WILL LIKELY BE A BREAK IN THE CLOUDS/RAIN...BEFORING SCATTERED SHOWERS RETURN. AN ADDITIONAL VORT MAX WILL PASS OVER SOCAL THURSDAY NIGHT ALONG WITH -18 TO -20C 500 MB TEMPS AND MOIST CYCLONIC FLOW ALOFT...SO WILL KEEP MENTION OF SCATTERED SHOWERS AND SCHC OF TSTMS THROUGH FRIDAY MORNING.

GOES PRECIPITABLE WATER IMAGERY ESTIMATES A PLUME OF 1.3 INCHES BEING TUGGED NORTHEAST WITH THE APPROACHING SHORTWAVE TROUGH. MODELS ARE CONSISTENT WITH BRINING 1+ INCH PW AIR TO THE COASTAL SECTIONS AND 30+ K INDEX VALUES TO MUCH OF OUR AREA TONIGHT AND THURSDAY. THIS WILL LIKELY HELP RAIN RATES BE A BIT MORE INTENSE THAN USUAL FOR THIS TIME OF YEAR. THE CURRENT FORECAST OF ONE HALF TO ONE INCH OF RAIN THROUGH THURSDAY STILL LOOKS GOOD...WITH LOCALLY HIGHER AMOUNTS AND RAINFALL RATES ON SOUTH TO SOUTWHEST FACING TERRAIN AND UNDER ANY CONVECTIVE ACTIVITY.

THINGS SHOULD DRY OUT FRIDAY NIGHT AND STAY DRY SATURDAY AS BRIEF UPPER LEVEL RIDGING MOVES IN.

.LONG TERM...

ANOTHER LONGWAVE TROUGH SWINGS INTO CALIFORNIA SUNDAY NIGHT...BRINGING A CHANCE OF RAIN TO AREAS NORTH OF POINT CONCEPTION SUNDAY...AND ALL AREAS SUNDAY NIGHT AND MONDAY. AS FLOW BECOMES MORE NORTHERLY IN ITS WAKE MONDAY NIGHT...SMALL CHC OF RAIN WILL BE LEFT OVER EASTERN PORTIONS. THERE IS STILL A CHANCE THIS NEXT SYSTEM WILL END UP BEING TOO FAR NORTH TO REALLY GIVE US MUCH CHANCE OF RAIN IN THE SOUTHLAND. NW TO W FLOW ALOFT CONTINUES OVER THE AREA TUESDAY AND WEDNESDAY...WITH A SLOW WARMING TREND. POSSIBLY SOME WEAK OFFSHORE FLOW WEDNESDAY FOR A BOOST IN TEMPS...BUT ITS TOO EARLY TO TELL FOR SURE.

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.LOX WATCHES/WARNINGS/ADVISORIES...

MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).



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