Clouds ahead of the frontal zone that will be entering the forecast area in a couple days. No heavy rain is expected, however very light rain is possible, but not warrant a light rain icon overnight.

A hefty severe scenario unfolding today with enough low level shear and instability for showers and thunderstorms today. A chance of supercells as well with tornadoes. This area will be on the Northern side of the better tornado dynamics which exist further South in the state. Aviation : Tops of the thunderstorms 40k.

Rain West of Los Angeles will be light, however in this area, the sky should just be cloudy with no rain chances.

BY TUESDAY EVENING, THE FRONTAL ZONE WILL BE LOCATED RIGHT ON THE VANDENBERG FORECAST AREA. BETWEEN NOON AND ABOUT 6PM TUESDAY EVENING, THE AREA WOULD HAVE AN ADDITIONAL 1/4 - 1/2 OF RAIN ON TOP OF THE MORNING AMOUNTS. 30 MPH 5,000 FOOT WINDS FROM THE SOUTHWEST WOULD GENERATE OROGRAPHICAL LIFTING ON THE SOUTHERN SLOPES OF THE LOCAL MOUNTAINS. HARDEST HIT AT THIS TIME WOULD BE THE SANTA BARBARA, AND VENTURA COUNTY MOUNTAINS WITH 1/2 - 1 OF RAIN POSSIBLE. SOME COLD AIR ALOFT COMING IN AND SOME PVA DYNAMICS WOULD GENERATE THE CHANCE OF THUNDERSTORMS AS WELL WITH THE FRONTAL ZONE AND SHOULD BE MONITORED CAREFULLY IN CASE ANY WATCHES NEED TO GO UP. WILL LEAVE THIS ONE ALONE AND MENTION THUNDERSTORMS ONLY AT THIS POINT. THE THUNDERSTORMS WOULD MAINLY BE FOR VANDENBERG FORECAST AREA TO KERN COUNTY TO SANTA BARBARA, SPREADING EASTWARD AS THE EVENING WEARS ON.

BY TUESDAY NIGHT, THE FRONTAL ZONE WOULD FINALLY MAKE IT INTO THE LOS ANGELES AREAS. THIS MAY HAVE A LOT OF POWER IF ALL GOES RIGHT FOR SOME HEAVY RAINS IN THE AREA WITH THE STRONG 30 KNT SOUTHWEST WINDS IN THE LOWER LEVELS. THE FRONTAL ZONE WOULD SHOW IT'S TRUE SHAPE FINALLY AS IT MOVES JUST PAST THE LOS ANGELES AREA TO THE EAST AS IT INTERACTS WITH THE HIGHER PEAKS OF THE SAN GABRIEL MOUNTAINS. THUNDERSTORMS ARE ALSO POSSIBLE AS THE SAME DYNAMICS FROM TUESDAY EVENING IN VANDENBERG AND SANTA BARBARA MOVE IN. THE WAY TO TELL IF THUNDERSTORMS ARE POSSIBLE WITH THIS FRONTAL PASSAGE ON TUESDAY NIGHT WILL BE TO MONITOR THE VANDENBERG AREAS AS IT PASSES THEM TUESDAY EVENING. THIS WILL TELL THE TALE DOWNRANGE FOR THE LOS ANGELES AREAS, EASTWARD. A 1/4 - 1/2 OF RAIN IS POSSIBLE WITH THE MAIN FRONTAL BURST FOR THE INLAND EMPIRE, AND ORANGE COUNTY / LOS ANGELES BASIN, ON DOWN TO SAN DIEGO COUNTY. THE MOUNTAINS WOULD SEE MORE IN THE RANGE OF 1/2 - 1 OF RAIN.

SPECIAL WEATHER STATEMENT ONTARIO WEATHER SERVICE ONTARIO CALIFORNIA DECEMBER 17 2007 - 2PM-PST FINAL FORECAST FOR TUESDAY - WEDNESDAY MORNING.BY TUESDAY EVENING, THE SNOW LEVEL WOULD RAISE AHEAD OF THE FRONTAL ZONE AS WARM, MOIST AIR MOVES IN, OTHERWISE KNOWN AS WARM AIR ADVECTION. THIS SHOULD UP THE SNOW LEVELS TO 8,500 FEET FOR THE TEHACHAPI, AND VENTURA COUNTY MOUNTAINS. THE SAN GABRIEL MOUNTAINS WOULD NOT BE IN MUCH OF THIS WARM AIR ADVECTION LIKE THE OTHER MOUNTAINS MENTIONED BEFORE-HAND, HOWEVER THE SNOW LEVEL WOULD SUSTAIN AT 7,500 FEET WITH 0-3 OF SNOW POSSIBLE. UP AT THE HIGHER PEAKS OF THE SAN GABRIELS, 4-6 OF SNOW IS POSSIBLE.8,000 FEET OVER THE SAN BERNARDINO COUNTY MOUNTAINS WOULD GIVE 0-3 OF SNOW POSSIBLE THERE, MOST LIKELY ON THE LOWER SIDE OF THAT SCALE FOR 8,000 FEET, AND THE PEAKS TOWARD THE UPPER SIDE.MOUNT SAN JACINTO WOULD BE GETTING THE 0-3 SCALE AS WELL AROUND THIS TIME.

THURSDAY NIGHT - THE THIN MOISTURE COLUMM WILL KEEP ANY RAIN OUT OF THE COACHELLA VALLEY AND HIGHER DESERTS, INCLUDING THE BORREGO SPRINGS DESERT.

BY THURSDAY NIGHT, THE WEST FLOW BEHIND THE FRONT WILL BE MOIST IN THE SAN DIEGO COUNTY MOUNTAIN AREA, SO PRECIPITATION IS EXPECTED THERE. THIS FLOW WILL ALSO BRING THE ONLY CHANCE FOR SAN DIEGO TO SEE RAIN OUT OF THIS STORM. ANY RAIN THAT FALLS WITH THIS SYSTEM WILL FALL DURING THIS TIME THERE.

A weak front will make it's way into the area today with light showers around. No more than 0.10 inch is expected with this. This should not make it East of Los Angeles as the Mountains do get in the way of the flow this time, unlike last time.

LATE THURSDAY MORNING, THIS FRONTAL ZONE WILL ALREADY BE IN THE VANDENBERG AREAS DROPPING LIGHT RAIN. THE WEST FLOW IN THE LOWER LEVELS WILL FAVOR THE AREAS WEST OF THE MOUNTAINS AND FOOTHILLS FOR THE BEST RAINS. THIS DOES NOT LOOK LIKE IT WILL PRODUCE A LOT OF RAIN FOR SANTA BARBARA EITHER DUE TO THE WESTERN FLOW IN THOSE LOWER LEVELS. WEAK CONVERGENCE ZONE WILL BE THE STORY WITH THIS FRONTAL ZONE UNLIKE THE LAST ONE SO DON'T EXPECT MUCH. MODERATE CONVERGENCE ALONG THE FRONT OVER NORTHERN SAN LUIS OBISPO COUNTY WILL GIVE OVER 0.10 OF RAIN THERE WITH IT, WHICH WILL BE MORE THAN VANDENBERG. OROGRAPHICS WILL START WORKING INTO THE KERN COUNTY MOUNTAINS FOR LIGHT SHOWERS IN THE AREA AHEAD OF THE FRONT.