storm coming this weekend

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d n News-NWS_LOX-A_COLD_SPRI 04/10 426
A COLD SPRING STORM SYSTEM WILL AFFECT SOUTHWESTERN CALIF...

NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
600 AM PDT THU APR 10 2003

...A COLD SPRING STORM SYSTEM WILL AFFECT SOUTHWESTERN CALIFORNIA LATE SATURDAY THROUGH MONDAY...

AN UPPER LEVEL LOW PRESSURE SYSTEM WAS CURRENTLY DEVELOPING OFF THE COAST OF WASHINGTON. THIS SYSTEM IS FORECAST TO EXPAND AND STRENGTHEN TODAY THROUGH FRIDAY...THEN BEGIN TO MOVE SLOWLY SOUTHWARD TOWARD THE CALIFORNIA COAST OVER THE WEEKEND. THIS WILL RESULT IN INCREASINGLY STRONG AND MOIST SOUTHWESTERLY FLOW ALOFT ACROSS CALIFORNIA...WHICH WILL LIKELY BRING PERIODS OF PRECIPITATION TO THE AREA FROM LATE SATURDAY THROUGH MONDAY.

IT APPEARS AS THOUGH A COUPLE OF DIFFERENT IMPULSES ROTATING AROUND THIS LARGE UPPER LOW WILL AFFECT SOUTHWESTERN CALIFORNIA SATURDAY THROUGH MONDAY...BEFORE THE TROUGH MOVES ACROSS THE AREA DURING MONDAY. THE STRENGTH AND TIMING OF EACH INDIVIDUAL IMPULSE WILL DETERMINE THE INTENSITY OF THE PRECIPITATION AND EXACTLY WHEN IT WILL OCCUR. AT THIS TIME...IT APPEARS THAT ONE BAND OF PRECIPITATION WILL MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY...WITH A SECOND BAND POSSIBLE SUNDAY EVENING INTO EARLY MONDAY. THEN...AS THE COLD AXIS OF THE UPPER TROUGH SWINGS ACROSS THE AREA ON MONDAY...ADDITIONAL SHOWER ACTIVITY IS LIKELY.

COOLING ALOFT WILL TAKE PLACE LATE IN THE WEEKEND AS THE COLD UPPER LEVEL CENTER SLOWLY APPROACHES CALIFORNIA. THIS WILL CAUSE THE ATMOSPHERE TO BECOME INCREASINGLY UNSTABLE...WHICH WILL INCREASE THE THREAT OF THUNDERSTORMS ACROSS THE AREA. IN ADDITION...SNOW LEVELS WILL LOWER THROUGH THE WEEKEND...LIKELY DOWN TO 5000 FEET BY LATE SUNDAY OR SUNDAY NIGHT. AS THE COLDEST AIR ASSOCIATED WITH THE UPPER SYSTEM MOVES ACROSS THE AREA LATE SUNDAY NIGHT AND MONDAY MORNING...SNOW COULD FALL AT LEVELS AS LOW AS 4000 FEET.

DUE TO THE COMPLEXITY OF THIS SYSTEM...IT IS NEARLY IMPOSSIBLE TO BE SPECIFIC WITH THE EXACT TIMING OF THE PRECIPITATION...OR WITH EXACT RAINFALL OR SNOWFALL TOTALS. HOWEVER...THIS STORM DOES HAVE THE POTENTIAL TO BRING MODERATE TO LOCALLY HEAVY AMOUNTS OF PRECIPITATION TO SOUTHWESTERN CALIFORNIA...AND HEAVY SNOWFALL TO THE MOUNTAINS. IN ADDITION...TRAVEL INTO OR THROUGH THE MOUNTAINS...ESPECIALLY ON INTERSTATE 5 OVER THE GRAPEVINE MAY BECOME DIFFICULT BY LATE SUNDAY OR MONDAY.

ALL RESIDENTS IN SOUTHWESTERN CALIFORNIA ARE URGED TO STAY TUNED TO NOAA WEATHER RADIO OR TO THEIR FAVORITE MEDIA OUTLETS FOR THE LATEST INFORMATION AND UPDATES ON THIS LATE SEASON STORM SYSTEM.

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BRUNO




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