064  
FXUS66 KSGX 141101  
AFDSGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN DIEGO CA  
300 AM PST SAT DEC 14 2019  
   
SYNOPSIS
 
 
A TROUGH MOVING THROUGH THE WEST THIS WEEKEND WILL BRING COOLER  
WEATHER, ALONG WITH GUSTY WINDS IN THE MOUNTAINS, DESERTS, AND  
COASTAL WATERS. THERE WILL ALSO BE A CHANCE OF A FEW LIGHT SHOWERS  
SATURDAY AFTERNOON AND EVENING ALONG AND WEST OF THE MOUNTAINS.  
WINDS WILL TURN OFFSHORE EARLY NEXT WEEK, BRINGING DRY AND WARMER  
WEATHER. NORTHEAST WINDS COULD BE GUSTY IN THE OFFSHORE, WIND-PRONE  
AREAS. THERE WILL BE ANOTHER SMALL CHANCE OF LIGHT SHOWERS BY THE  
MIDDLE OF NEXT WEEK.  
 

 
   
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
 
 
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO  
COUNTIES...  
 
SATELLITE IMAGERY OVERNIGHT HAD A SOLID MARINE CLOUD DECK FROM THE  
INNER COASTAL WATERS, EXTENDING INLAND UP TO 40 MILES. THESE CLOUDS  
HAD FILLED IN MOST OF THE I.E. BY 3 AM PST. THE SFC PRESSURE  
GRADIENTS WERE MODERATELY ONSHORE AND TRENDING ONSHORE FROM KSAN TO  
THE DESERTS. PEAK WESTERLY WINDS WERE 20-30 MPH WITH GUSTS 35-45  
MPH.  
 
A SHORTWAVE POISED OFF THE PACNW COAST THIS MORNING WILL DIVE SE  
INTO THE GREAT BASIN THIS WEEKEND, DRIVING GUSTY ONSHORE FLOW OVER  
SOCAL. A DEEPENING MARINE LAYER MAY PRODUCE SOME SCATTERED, LIGHT  
SHOWERS AS WELL BY THIS AFTERNOON OR EVENING ALONG AND WEST OF THE  
MOUNTAINS. THE MAIN CONCERN WITH THIS SYSTEM WILL BE THE GUSTY  
WESTERLY WINDS OVER THE MTNS/DESERTS/COASTAL WATERS. A WIND ADVISORY  
HAS BEEN POSTED INLAND AND A SMALL CRAFT ADVISORY IS IS EFFECT FOR  
THE COASTAL WATERS TOMORROW INTO SUNDAY.  
 
BEHIND THE WAVE, A TRANSIENT RIDGE WILL BUILD A STRONG SFC HIGH INTO  
THE GREAT BASIN EARLY NEXT WEEK (1040+ MBS), FORCING THE WINDS TO  
TURN OFFSHORE ACROSS SOCAL. MODERATE TO LOCALLY STRONG E-NE WINDS  
ARE POSSIBLE THROUGH THE PASSES AND ON THE WIND-PRONE COASTAL  
SLOPES, BUT UPPER SUPPORT IS WEAK TO NIL. THIS WILL MEAN DRY AND  
WARMER WEATHER FOR MONDAY AND TUESDAY, WITH THE WARMEST WEATHER  
ALONG THE COAST, SETTING UP A COUPLE OF NICE BEACH DAYS.  
 
ANOTHER SHORTWAVE FOLLOWS THE RIDGE FOR THE MIDWEEK PERIOD AND MAY  
GENERATE SOME LIGHT RAIN OR SHOWERS LATE WEDNESDAY OR THURSDAY BUT  
CHANCES APPEAR TO BE DWINDLING HERE AS IT BECOMES OVERWHELMED BY THE  
ABUNDANCE OF DRY, CONTINENTAL AIR. A SHALLOW, TRANSIENT RIDGE FLOATS  
BY TOWARD THE END OF NEXT WEEK, AGAIN WITH SOME WARMING WEST OF THE  
MOUNTAINS. A LONGWAVE TROUGH APPEARS OVER THE EASTPAC NEXT WEEKEND  
AND POSES A POTENTIAL FOR MORE SUBSTANTIAL PRECIPITATION THEN, BUT  
THIS IS NEAR THE END OF THE FORECAST PERIOD WITH LOW CONFIDENCE.  
 

 
   
AVIATION
 
 
141045Z...COAST AND VALLEYS...BKN-OVC CIGS 700-900 FT MSL WITH TOPS  
TO 1400 FT MSL EXTEND UP TO 30 MILES INLAND THIS MORNING, IMPACTING  
ALL TAF SITES WEST OF THE MTNS. AREAS OF VIS 2-4 MILES, LOCALLY 1  
MILE IN FOG. HIGHER TERRAIN WILL BE OBSCURED. EXPECT CLEARING INLAND  
AROUND 17Z AND PARTIAL CLEARING AT THE COAST AFTER 20Z. LOW CIGS  
WILL BEGIN SPREADING INLAND AGAIN THIS AFTERNOON, WITH HIGHER BASES  
AND TOPS.  
 
MOUNTAINS/DESERTS...SCT CLOUDS ABOVE 20000 FT MSL WITH UNRESTRICTED  
VIS THROUGH TONIGHT. GUSTY ONSHORE WINDS WILL DEVELOP THROUGH THE  
MOUNTAIN PASSES AND ALONG THE DESERT-FACING SLOPES THIS AFTERNOON,  
WITH GUSTS TO 50 KT POSSIBLE. THIS WILL PRODUCE STRONG UP/DOWNDRAFTS  
AND LLWS OVER AND EAST OF THE MTNS AFTER 00Z SUNDAY.  
 

 
   
MARINE
 
 
A LARGE, WEST-NORTHWEST SWELL WITH A PERIOD OF 15-17 SECONDS WILL  
COMBINE WITH A FRESH SWELL WITH A PERIOD OF 7-9 SECONDS TO PRODUCE  
COMBINED SEAS OF 9 TO 12 FT THROUGH SUNDAY. WEST NORTHWEST WINDS  
WILL INCREASE OVER THE OUTER COASTAL WATERS, PEAKING TONIGHT INTO  
SUNDAY MORNING WITH GUSTS 25 TO 30 KNOTS, AND LOCALLY TO 35 KNOTS  
NEAR SAN CLEMENTE ISLAND. A SMALL CRAFT ADVISORY IS IN EFFECT FOR  
ALL OF THE COASTAL WATERS. THE COMBINATION OF THE WINDS AND SWELLS  
WILL CREATE HAZARDOUS BOATING CONDITIONS FOR MARINERS THROUGH  
SUNDAY.  
 

 
   
BEACHES
 
 
A WEST-NORTHWEST SWELL WITH A PERIOD OF 15-17 SECONDS WILL BRING  
HIGH SURF AND STRONG RIP CURRENTS TO THE BEACHES THROUGH SUNDAY,  
PEAKING THIS MORNING. EXPECT TO SEE SURF CONDITIONS OF 6 TO 9 FEET  
ALONG THE SAN DIEGO COUNTY BEACHES WITH SLIGHTLY LOWER VALUES FOR  
THE ORANGE COUNTY BEACHES. HIGH TIDES OVER 6 FEET ALONG WITH THE  
SURF MAY CONTRIBUTE TO LOCAL BEACH EROSION.  
 

 
   
SKYWARN
 
 
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE  
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.  
 

 
   
SGX WATCHES/WARNINGS/ADVISORIES
 
 
CA...WIND ADVISORY FROM 1 PM SATURDAY TO 10 AM PST SUNDAY FOR APPLE  
AND LUCERNE VALLEYS-COACHELLA VALLEY-RIVERSIDE COUNTY  
MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY  
DESERTS-SAN DIEGO COUNTY MOUNTAINS-SAN GORGONIO PASS NEAR  
BANNING.  
 
HIGH SURF ADVISORY UNTIL 4 PM PST SUNDAY FOR ORANGE COUNTY  
COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.  
 
PZ...SMALL CRAFT ADVISORY FROM 4 AM SATURDAY TO 4 PM PST SUNDAY FOR  
COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER  
AND OUT TO 30 NM-WATERS FROM SAN MATEO POINT TO THE MEXICAN  
BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE  
ISLAND.  
 

 
 

 
 
PUBLIC...10  
AVIATION/MARINE/BEACHES...PG  
 
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