A STRONG AND VERY COLD UPPER LOW OFF THE PACIFIC NORTHWEST COAST THIS AFTERNOON IS FORECAST TO DROP SOUTHWARD ALONG OR JUST OFF THE CALIFORNIA COAST TONIGHT AND TUESDAY…TRACKING RIGHT ACROSS SOUTHWESTERN CALIFORNIA TUESDAY NIGHT. THIS SYSTEM WILL THREATEN THE REGION WITH A VARIETY OF WEATHER HAZARDS… INCLUDING POSSIBLY HEAVY SHOWERS…THUNDERSTORMS…GUSTY WINDS AND MODERATE TO HEAVY SNOW ACCUMULATIONS WITH VERY LOW SNOW LEVELS. CLOUDS WILL INCREASE ACROSS THE REGION TONIGHT. SHOWERS WILL LIKELY DEVELOP NORTH OF POINT CONCEPTION EARLY TUESDAY MORNING..THEN BECOME LIKELY IN ALL AREAS TUESDAY AFTERNOON AND EVENING. SHOWERS WILL BEGIN TO DECREASE FROM NORTHWEST TO SOUTHEAST ACROSS THE REGION LATE TUESDAY NIGHT. SCATTERED SHOWERS WILL LINGER INTO WEDNESDAY… ESPECIALLY ACROSS NORTH FACING SLOPES OF THE LOS ANGELES AND VENTURA COUNTY MOUNTAINS AND THE ANTELOPE VALLEY. WHILE MOISTURE WILL INITIALLY BE FAIRLY LIMITED WITH THIS SYSTEM… IT MAY BEGIN TO TAP INTO SOME DEEPER PACIFIC MOISTURE AS IT MOVES INTO SOUTHWESTERN CALIFORNIA LATE TUESDAY AND TUESDAY NIGHT. VERY COLD AIR ALOFT ASSOCIATED WITH THE APPROACHING UPPER LOW WILL CAUSE INCREASING INSTABILITY THROUGH THE ATMOSPHERE TUESDAY AFTERNOON INTO TUESDAY NIGHT… LEADING TO A CHANCE OF THUNDERSTORMS… SOME OF WHICH COULD PRODUCE SMALL HAIL…VERY HEAVY DOWNPOURS AND GUSTY WINDS. IT IS NOT OUT OF THE QUESTION THAT SOME HAIL COULD APPROACH SEVERE LIMITS…AND SOME WATERSPOUTS IN THE COASTAL WATERS COULD COME ASHORE AS WEAK TORNADOS. DUE TO THE COLD NATURE OF THIS STORM… SNOW WILL LIKELY FALL AT VERY LOW ELEVATIONS ACROSS THE REGION… IMPACTING TRAVEL ON MANY MAJOR ROUTES INTO AND THROUGH THE MOUNTAINS. SNOW LEVELS ARE EXPECTED TO START OUT BETWEEN 3500 AND 4000 FEET ON TUESDAY… THEN WILL LOWER TO BETWEEN 2000 AND 2500 FEET TUESDAY NIGHT. THIS WOULD BRING ACCUMULATING SNOWS INTO PORTIONS OF THE ANTELOPE VALLEY AND CUYAMA VALLEYS… WHERE UP TO 4 INCHES ARE POSSIBLE… ESPECIALLY IN THE FOOTHILLS. AN INCH OR TWO OF SNOW MAY EVEN FALL OVER THE HIGHER ELEVATIONS OF THE SANTA MONICA MOUNTAINS AND THE INTERIOR VALLEYS OF SAN LUIS OBISPO COUNTY. SNOW MAY EVEN OCCASIONALLY FALL IN THE HIGHER FOOTHILLS ABOVE THE LOS ANGELES AND VENTURA COUNTY VALLEYS…BUT NO SNOW ACCUMULATIONS ARE EXPECTED THERE. Instruction: SINCE THE PRECIPITATION WILL BE SHOWERY IN NATURE… RAINFALL TOTALS TUESDAY THROUGH EARLY WEDNESDAY WILL BE HIGHLY VARIABLE… BUT WILL AVERAGE ONE HALF INCH TO ONE INCH IN COASTAL AND VALLEY AREAS… WITH UP TO 1.50 INCHES IN THE FOOTHILLS AND MOUNTAINS. ANY AREAS THAT RECEIVE THUNDERSTORMS MAY RECEIVE HIGHER RAINFALL TOTALS. IT APPEARS THAT THE HIGHEST RAINFALL TOTALS WILL OCCUR ACROSS LOS ANGELES COUNTY… ESPECIALLY ACROSS EASTERN SECTIONS… INCLUDING THE STATION AND MORRIS BURN AREAS. THESE AREAS WILL ALSO HAVE THE BEST CHANCE OF RECEIVING THUNDERSTORMS WITH HIGH INTENSITY RAINFALL. RESIDENTS IN AND BELOW THE RECENT BURN AREAS SHOULD BE PREPARED FOR THE POTENTIAL FOR VERY HEAVY DOWNPOURS. FLASH FLOOD WATCHES MAY NEED TO BE ISSUED FOR THE RECENT BURN AREAS OF LOS ANGELES COUNTY… ESPECIALLY IF THE SYSTEM TAKES A MORE OVER-WATER TRAJECTORY. IN THE MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES…SNOW ACCUMULATIONS OF 6 TO 12 INCHES ARE EXPECTED… WITH LOCAL TOTALS AS HIGH AS 16 INCHES IN THE SAN GABRIELS. IN THE MOUNTAINS OF SAN LUIS OBISPO AND SANTA BARBARA COUNTIES…3 TO 6 INCHES OF SNOW ARE EXPECTED. PLEASE REFER TO (LAXWSWLOX) FOR MORE DETAILS. RESIDENTS OF SOUTHWEST CALIFORNIA ARE URGED TO STAY TUNED TO THE LATEST NATIONAL WEATHER SERVICE STATEMENTS AND POSSIBLE WATCHES AND WARNINGS AS THIS WEATHER SITUATION CONTINUES TO DEVELOP.