062  
FXUS66 KSGX 171018  
AFDSGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN DIEGO CA  
218 AM PST WED JAN 17 2018  
   
SYNOPSIS
 
 
A HIGH PRESSURE RIDGE ALOFT WILL KEEP OUR WEATHER FAIR AND MILD  
THROUGH THURSDAY WITH ABOVE AVERAGE TEMPERATURES. HIGH SURF WILL  
CONTINUE INTO SATURDAY, AND PATCHY FOG MAY DEVELOP NEAR THE COAST  
EACH NIGHT AS WELL. A FAST-MOVING LOW PRESSURE TROUGH WILL DRAG A  
COLD FRONT ACROSS THE REGION ON FRIDAY, WITH GUSTY WESTERLY WINDS  
AND SCATTERED SHOWERS. PRECIPITATION WILL BE LIGHT. FAIR, DRY AND  
MILD AGAIN OVER THE WEEKEND AND INTO NEXT WEEK.  
 

 
   
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
 
 
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO  
COUNTIES...  
 
HIGH CLOUDS WERE DRIFTING FROM THE NORTH OVER SOCAL AND BEGINNING TO  
THIN EARLY THIS MORNING, REVEALING PATCHES OF FOG. SURFACE DEWPOINTS  
WERE WELL INTO THE 50S OVER COASTAL AREAS AT 2 AM PST, SO A FEW  
HOURS OF CLEAR SKIES TOWARD DAWN MAY BE SUFFICIENT FOR SOME POCKETS  
OF DENSE FOG TO FORM. WEAK EASTERLY DRAINAGE FLOW SHOULD KEEP ANY  
WIDESPREAD FOG CONFINED TO COASTAL AREAS, IF AT ALL. THE SURFACE  
PRESSURE GRADIENT WAS WEAK OFFSHORE FROM THE DESERTS.  
 
A HIGH PRESSURE RIDGE WILL BE BUILDING OVER THE SW THROUGH THURSDAY  
KEEPING SKIES FAIR AND TEMPERATURES ABOVE AVERAGE. THE RIDGE WILL  
FLATTEN ON FRIDAY AS A TROUGH SLIDES EAST ACROSS THE STATE AND  
DEEPENS. THE TROUGH HAS A MODEST AMOUNT OF PACIFIC MOISTURE TO WORK  
WITH, BUT WILL BE MOVING FAST, LIMITING ANY PRECIP POTENTIAL ACROSS  
THE SOUTHLAND. STILL, DYNAMICS AND MOISTURE LOOK SUFFICIENT FOR AT  
LEAST SOME LIGHT SHOWERS ANYTIME BETWEEN FRI AND SAT MORNING.  
 
AHEAD OF THE TROUGH, WEST WINDS WILL BE INCREASING ON THU, AND  
BECOME STRONG AND GUSTY ON FRI INTO SAT MORNING OVER THE COASTAL  
WATERS, MTS AND DESERTS. IT WILL BE MUCH COOLER ON FRI/SAT AS MAX  
TEMPS FALL BELOW AVERAGE, THEN GRADUAL WARMING AGAIN EARLY NEXT WEEK  
AS WEAK HIGH PRESSURE ALOFT IS REESTABLISHED OVER THE SW.  
 

 
   
AVIATION
 
 
171000Z...COAST...PATCHY LOW CLOUDS AND FOG THROUGH 16Z. WHEN/WHERE  
THESE PATCHES OCCUR, BASES WILL VARY BETWEEN 100-800 FEET MSL, WITH  
VIS 0-5SM. PREVAILING VIS AT THE COAST 4-7SM. A SIMILAR PATCHY LOW  
CLOUD/FOG SCENARIO WILL DEVELOP ALONG THE COAST AFTER 04Z THIS  
EVENING. ACROSS MOST OF THE REGION, VFR CONDITIONS AND SCATTERED  
HIGH CLOUDS WILL PREVAIL TODAY AND TONIGHT.  
 

 
   
MARINE
 
 
PATCHY FOG WITH VIS 1NM IS FORECAST THIS MORNING AND AGAIN TONIGHT.  
ONSHORE FLOW WILL INCREASE THURSDAY AND FRIDAY AS A STORM MOVES INTO  
THE COASTAL WATERS. IT WILL BRING GALES AND HAZARDOUS SEAS FRIDAY  
AND SATURDAY. STAY TUNED TO FORECASTS AND OTHER HAZARD BULLETINS  
WHEN THEY ARE ISSUED LATER THIS WEEK.  
 

 
   
BEACHES
 
 
HIGH SURF WILL GRADUALLY DECREASE TODAY INTO THURSDAY. A NEW SWELL  
ASSOCIATED WITH A PACIFIC STORM WILL ARRIVE FRIDAY, PEAK FRIDAY  
NIGHT, AND GRADUALLY DECREASE SATURDAY. CHECK THE HIGH SURF ADVISORY  
AND SURF FORECAST FOR DETAILS.    
SKYWARN
 
 
SKYWARN ACTIVATION WILL NOT BE NEEDED THROUGH THURSDAY.  
 

 
   
SGX WATCHES/WARNINGS/ADVISORIES
 
 
CA...HIGH SURF ADVISORY UNTIL 8 PM PST SATURDAY FOR ORANGE COUNTY  
COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS.  
 
PZ...NONE.  
 

 
 

 
 
PUBLIC...JAD  
AVIATION/MARINE/BEACHES...MM  
 
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