AREA FORECAST DISCUSSION
FXUS66 KLOX 210438
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
840 PM PST SUN FEB 20 2005
...VERY HEAVY RAIN TONIGHT AND MONDAY...BLIZZARD-LIKE CONDITIONS ABOVE 6000 FEET...
.SHORT TERM...VERY IMPRESSIVE COMMA-HEAD PATTERN ON SATELLITE IMAGERY THIS EVENING OFF THE COAST OF SOUTH-CENTRAL CALIFORNIA. PLUME OF COOLING CLOUD TOPS NOW OVER THE AREA...AND STRETCHING SOUTHWEST. MODERATE TO LOCALLY HEAVY RAIN HAS FILLED IN QUICKLY IN THE LAST HOUR SOUTH OF POINT CONCEPTION. BACK EDGE OF THE MAIN FRONTAL BAND HAS ACTUALLY PASSED EAST OF POINT CONCEPTION AND MODELS HANDLE THIS FEATURE DIFFERENTLY. THE GFS BLOWS THE FEATURE THROUGH THE AREA BY 12Z...WHILE THE NAM SLOWS THE EASTWARD MOVEMENT DOWN IN RESPONSE TO SHORTWAVE ENERGY DIVING SOUTH ON THE BACKSIDE OF THE UPPER LOW. PREFER TO GO WITH NAM. EVEN IF THE FRONTAL BAND RAIN SLIDES EAST AHEAD OF THE FRONT...STRONG SOUTHERLY FLOW WILL NO DOUBT FEED REGENERATION OF ADDITIONAL BANDS OF RAIN AND OGRAPHIC RAIN THROUGH MONDAY. NOT TO MENTION HELP FROM ADDITIONAL UPPER LEVEL DYNAMICS AND DIFFLUENT FLOW.
WE ARE VERY CONCERNED ABOUT THE AMOUNT OF RAIN THE AREA COULD SEE OVERNIGHT SOUTH OF POINT CONCEPTION. THE 1 TO 3 INCHES OVER THE COAST AND VALLEY...AND 3 TO 6 INCHES IN THE MOUNTAINS THROUGH MONDAY MAY BE ON THE CONSERVATIVE SIDE...IF THE NAM IS RIGHT. WE ARE ALREADY SEEING RATES NEAR ONE HALF INCH PER HOUR OVER THE SANTA YNEZ RANGE AND THE FOOTHILLS OF LA COUNTY AS I TYPE. FLOOD ADVISORIES HAVE ALREADY BEEN ISSUED AND FLASH FLOOD WARNINGS WILL NO DOUBT BE ISSUED IN THE NEXT COUPLE OF HOURS.
IN THE UPDATE FOR THE WINTER STORM WARNING...WE HIGHLIGHTED BLIZZARD-LIKE CONDITIONS ABOVE 6000 FEET. HEAVY SNOW FALLING AT THE RATE OF 1 TO 3 INCHES PER HOUR COMBINED WITH SOUTHERLY WINDS 30 TO 40 MPH AND GUSTY WILL RESULT IN BLIZZARD CONDITIONS AT THE HIGHEST ELEVATIONS...INCLUDING THE SKI RESORTS. PEOPLE SHOULD NOT TRY TO VENTURE INTO OR OUT OF THE HIGH MOUNTAINS THROUGH MONDAY AS CONDITIONS WILL BE VERY TREACHEROUS. ADDITIONAL SNOWFALL THROUGH TUESDAY WILL BE 2 TO 4 FEET...FOR STORM TOTALS OF 4 TO 8 FEET ABOVE 7000 FEET...AND 2 TO 4 FEET BETWEEN 5000 AND 7000 FEET ELEVATION.
HAVE UPDATED ZONES THIS EVENING FOR THE ISSUANCE OF A WIND ADVISORY NORTH OF POINT CONCEPTION AND FOR THE SANTA BARBARA SOUTH COAST AND SANTA MONICA MOUNTAINS. I ALSO ADDED SMALL HAIL AND GUSTY WINDS TO ACCOMPANY THE FORECAST OF THUNDERSTORMS MONDAY AND MONDAY NIGHT.
VERY COLD CORE UNDER THE UPPER LOW WILL SURELY ALLOW FOR ANY THUNDERSTORMS THAT DO DEVELOP TO CONTAIN HAIL.
...FROM PREVIOUS DISCUSSION...
RAINFALL AMOUNTS WITH THE FRONTAL PASSAGE TONIGHT/MONDAY WILL BE QUITE IMPRESSIVE (RANGING FROM 1"-3" FOR THE COASTAL PLAIN UP TO 3"-6" INCHES IN THE HIGHER TERRAIN). OVERALL...RAINFALL TOTALS FOR THIS EVENT (THURSDAY FEB 17 TO TUESDAY FEB 22) ARE EXPECTED TO RANGE FROM 4"-10" FOR THE COASTAL PLAIN WITH 10"-20" INCHES IN THE MOUNTAINS. GIVEN THE GROUND IS ALREADY SATURATED...THE ADDITIONAL HEAVY RAINFALL EXPECTED THE NEXT COUPLE OF DAYS WILL HEIGHTEN FLASH FLOODING CONCERNS ACROSS MOST OF THE FORECAST AREA. SEE THE LATEST FLASH FLOOD WATCH...LAXFFALOX...FOR THE LATEST INFORMATION.
WINTER STORM WARNINGS REMAIN IN EFFECT THROUGH TUESDAY. SNOW LEVELS WILL GENERALLY RANGE BETWEEN 5000 AND 6000 FEET ON TONIGHT AND MONDAY...BUT COULD LOWER TO AS LOW AS 4000 FEET ON TUESDAY. LOOK FOR SIGNIFICANT SNOWFALL ACCUMULATIONS AND STRONG SOUTHERLY WINDS ACROSS THE HIGHER ELEVATIONS OF THE VENTURA AND LOS ANGELES COUNTY MOUNTAINS. FOR MORE INFORMATION ON THE WINTER STORM CONDITIONS IN THE MOUNTAINS...PLEASE REFER TO THE LATEST WINTER STORM WARNING PRODUCT...LAXWSWLOX.
EXTENDED...MEDIUM RANGE MODEL AGREEMENT LOOKS PRETTY GOOD THROUGH THE REST OF THE WEEK. UPPER LOW MOVES EAST OF THE AREA ON WEDNESDAY WITH ONLY A SLIGHT SHOWER THREAT FOR THE AREA WEDNESDAY. FOR THE REST OF THE WEEK...A WEAK UPPER RIDGE BUILDS OVER THE EASTERN PACIFIC. THIS SHOULD KEEP THE AREA DRY THROUGH ATURDAY...ALTHOUGH SOME MID/HIGH CLOUDS MAY DRIFT OVER THE AREA. AS FOR TEMPS...EXPECT BELOW NORMAL READINGS TO CONTINUE THROUGH SATURDAY.
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.LOX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH (SEE LAXFFALOX).
WINTER STORM WARNING (SEE LAXWSWLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
GALE WARNING (SEE LAXCWFLOX).
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MOYER/THOMPSON