Weekend weather

11:04 AM
Thu 11/18From: NWS 11:02 AM 11/18/2010
A LARGE UPPER LEVEL TROUGH OF LOW PRESSURE APPROACHING FROM THE NORTHWEST WILL MOVE OVER SOUTHWEST CALIFORNIA AND A COUPLE OF IMPULSES WILL MOVE THROUGH THIS WEEKEND. THE FIRST IMPULSE ROTATING AROUND THE MAIN TROUGH WILL MOVE THROUGH ON SATURDAY. THIS WILL LIKELY BRING PRECIPITATION... POSSIBLY HEAVY AT TIMES. SHOWERS WILL TAPER OFF LATE SATURDAY. A SECOND UPPER LEVEL DISTURBANCE COULD ENHANCE PRECIPITATION AGAIN SUNDAY WITH SHOWERS LINGERING INTO MONDAY. THIS STORM SYSTEM WILL BRING MUCH COLDER WEATHER WITH LOCAL STRONG GUSTY WESTERLY WINDS. THE STRONGEST WINDS WILL BE IN THE MOUNTAINS AND DESERTS...BUT THERE WILL ALSO BE GUSTY WINDS IN THE COASTAL AREAS AND INLAND VALLEYS SATURDAY. LOCAL WINDY CONDITIONS WILL CONTINUE IN THE MOUNTAINS AND DESERTS THROUGH SUNDAY. PRELIMINARY RAINFALL ESTIMATES THROUGH MONDAY RANGE FROM ABOUT AN INCH WEST OF THE MOUNTAINS... WITH ONE TO THREE INCHES ON THE COASTAL MOUNTAIN SLOPES. THERE COULD BE ABOUT A THIRD TO TWO THIRDS OF AN INCH OF RAIN IN THE HIGH DESERTS AND NEAR A QUARTER INCH IN THE LOWER DESERTS. THE SNOW LEVEL WILL START OUT HIGH...ABOVE 7000 FEET...AND THEN LOWER TO ABOUT 5000 FEET NORTH AND 5500 FEET SOUTH SUNDAY INTO MONDAY. SNOW ACCUMULATIONS MAY REACH ABOUT 3 TO 6 INCHES BETWEEN 5000 AND 7000 FEET WITH 6 TO 12 INCHES ABOVE 7000 FEET IN THE SAN BERNARDINO AND RIVERSIDE COUNTY MOUNTAINS. A FEW INCHES OF SNOW COULD EVENTUALLY ACCUMULATE ON THE HIGHEST PEAKS OF THE SAN DIEGO COUNTY MOUNTAINS SUNDAY INTO MONDAY. THE RAIN WILL MAKE ROADS SLICK AND MOTORISTS SHOULD USE EXTRA CAUTION. THERE COULD BE FLOODING OF POORLY DRAINED LOW LYING AREAS AND POSSIBLE MUD SLIDES IN AND BELOW STEEP TERRAIN AND RECENTLY BURNED AREAS. FOG... SNOW AND BLOWING SNOW... WILL REDUCE VISIBILITY IN THE MOUNTAINS AT TIMES. Area: ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS-SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-SAN DIEGO COUNTY VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS-RIVERSIDE COUNTY MOUNTAINS-SANTA ANA MOUNTAINS AND FOOTHILLS-SAN DIEGO COUNTY MOUNTAINS-APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS- Affected Counties or parts of: San Diego, Riverside, San Bernardino, Orange