366  
FXUS66 KSGX 270413  
AFDSGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN DIEGO CA  
913 PM PDT SUN MAR 26 2017  
   
SYNOPSIS
 
 
PARTLY CLOUDY AND MILD OVERNIGHT WITH INCREASING WIND OVER THE  
MOUNTAINS AND DESERTS. A LOW PRESSURE TROUGH PASSING TO THE  
NORTHEAST WILL BRING COOLING MONDAY, AND A CHANCE OF A FEW LIGHT  
SHOWERS ALONG AND WEST OF THE MOUNTAINS. WESTERLY WINDS WILL BECOME  
QUITE GUSTY OVER THE MOUNTAINS AND DESERTS, TURNING NORTH AND THEN  
NORTHEASTERLY EARLY TUESDAY. WARMER ON TUESDAY AND WEDNESDAY, THEN  
COOLER THURSDAY AND FRIDAY AS STRONG ONSHORE FLOW DEVELOPS.  
 

 
   
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE
 
 
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO  
COUNTIES...  
 
IR SATELLITE IMAGERY THIS EVENING SHOWED AREAS OF LOW CLOUDS ALONG  
AND WEST OF THE MTS, AND PATCHY HIGHER CLOUDS DRIFTING SOUTHEAST  
OVER SOCAL. THE 00Z MIRAMAR SOUNDING HAD A MODEST INCREASE IN  
MOISTURE AND WAS QUITE STABLE ABOVE 3000 FT. SURFACE PRESSURE  
GRADIENTS WERE HOLDING STEADY AROUND 6 MBS ONSHORE KSAN TO THE  
DESERTS. THROUGH 8 PM PDT, PEAK WIND GUST REPORTS HAVE LARGELY BEEN  
WELL BELOW 40 MPH.  
 
WIND ADVISORIES HAVE BEEN POSTED FROM EARLY MONDAY MORNING THROUGH  
TUESDAY AFTERNOON. SEE LAXNPWSGX FOR DETAILS. NO FORECAST CHANGES.  
 
FROM PREVIOUS DISCUSSION...  
 
A BROAD AREA OF LOW PRESSURE IS CURRENTLY OFF THE PAC NW COAST, AND  
THE TROUGH WILL MOVE E/SE AND DIG INTO SO-CAL BY MONDAY MORNING.  
MOISTURE WILL BE RATHER LIMITED HERE AND BE MOSTLY UNDER 850 MB, SO  
ANY PRECIP THAT OCCURS WILL BE LIGHT, WITH BEST CHANCES IN SAN DIEGO  
COUNTY DUE TO BETTER WESTERLY FLOW FROM OVER THE WATER. WE WILL  
MAINTAIN THE SLIGHT CHANCES OF PRECIP FOR NOW FOR LATE TONIGHT AND  
MONDAY MORNING. LOCAL WIND GUSTS OVER 50 MPH WILL OCCUR IN THE  
MOUNTAINS AND DESERTS MONDAY DUE TO THE GRADIENTS ALOFT, AND A WIND  
ADVISORY HAS BEEN ISSUED FOR MOST OF THESE AREAS STARTING AT 4 PM  
MONDAY. AFTER THE TROUGH MOVES EAST LATE MONDAY NIGHT/TUESDAY  
MORNING, A SURFACE HIGH FROM THE PACIFIC WILL SPREAD INTO NEVADA AND  
RESULT IN SOME MODERATE OFFSHORE FLOW. A WIND ADVISORY COVERS THE  
AREA FROM THE SANTA ANA MOUNTAINS EAST AND NORTHEAST THROUGH THE  
INLAND EMPIRE AND SAN BERNARDINO/RIVERSIDE COUNTY MOUNTAINS MONDAY  
NIGHT THROUGH 2 PM TUESDAY. RIDGING FROM THE WEST COMBINED WITH THE  
MARINE LAYER BECOMING EITHER VERY SHALLOW OR NON-EXISTENT WILL  
RESULT IN WARMER DAYS TUESDAY/WEDNESDAY.  
 
BY THURSDAY, THE NEXT TROUGH WILL DIG SOUTH OVER THE INTERIOR  
WESTERN US, BUT THE INLAND TRACK WILL MEAN THAT PRECIP CHANCES WILL  
BE QUITE LOW HERE, UNLESS THE TROUGH ENDS UP FURTHER WEST THAN WHAT  
THE MODELS SHOW. THE MAIN EFFECTS HERE WILL BE THE COOLER WEATHER  
AND WINDY AREAS IN THE MOUNTAINS AND DESERTS. IF THE TROUGH SHIFTS  
EAST WITHOUT CLOSING OFF OVER THE WEEKEND, WE SHOULD HAVE FAIR  
WARMER WEATHER BUT WITH A POSSIBILITY OF OFFSHORE FLOW NEXT WEEKEND.  
 

 
   
AVIATION
 
 
270400Z...BKN-OVC STRATUS THROUGH AT LEAST 17Z MONDAY, ALONG THE  
COAST, VALLEYS AND LOWER COASTAL MOUNTAIN SLOPES, WITH BASES 1500-  
3000 FT MSL, TOPS 4000-4500 FT MSL AND VIS RESTRICTIONS TO 3 SM.  
 
W TO NW WINDS STRENGTHENING OVERNIGHT THROUGH MONDAY MORNING,  
BECOMING 15-25 KT WITH GUSTS TO 40 KT OVER THE MOUNTAIN RIDGES,  
DESERT SLOPES, PASSES/CANYONS AND INTO WIND-FAVORED DESERT AREAS,  
RESULTING IN STRONG UP/DOWNDRAFTS AND LLWS OVER AND EAST OF THE  
MOUNTAINS. WINDS SHIFTING AND BECOMING QUITE STRONG NW MONDAY  
EVENING, RESULTING IN STRONG UP/DOWNDRAFTS AND LLWS OVER AND WEST OF  
THE MOUNTAINS AND IMMEDIATELY BELOW THE CANYONS AND PASSES.  
 

 
   
MARINE
 
 
STRONG NORTHWEST WINDS WITH GUSTS OF 25 TO 30 KT GENERALLY TO  
CONTINUE THROUGH TUESDAY WITH COMBINED SEAS AROUND 10 FT. A SMALL  
CRAFT ADVISORY REMAINS IN EFFECT.  
 

 
   
BEACHES
 
 
WEST-NORTHWEST SWELLS AROUND 290 DEGREES WILL CREATE ELEVATED SURF  
OF 3-6 FEET THROUGH MOST OF THE WEEK. SETS OF 7 FEET WILL BE  
POSSIBLE AT TIMES. THESE SURF CONDITIONS WILL BE ACCOMPANIED BY AN  
INCREASED RISK OF STRONG RIP CURRENTS.  
 

 
   
SGX WATCHES/WARNINGS/ADVISORIES
 
 
CA...WIND ADVISORY FROM 4 AM TO 10 PM PDT MONDAY FOR APPLE AND  
LUCERNE VALLEYS-SAN DIEGO COUNTY DESERTS-SAN DIEGO COUNTY  
MOUNTAINS.  
 
WIND ADVISORY FROM 10 PM MONDAY TO 2 PM PDT TUESDAY FOR SAN  
BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-  
SANTA ANA MOUNTAINS AND FOOTHILLS.  
 
WIND ADVISORY FROM 4 AM MONDAY TO 2 PM PDT TUESDAY FOR RIVERSIDE  
COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN  
GORGONIO PASS NEAR BANNING.  
 
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 8 PM PDT  
TUESDAY FOR WATERS FROM SAN MATEO POINT TO THE MEXICAN  
BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE  
ISLAND.  
 
SMALL CRAFT ADVISORY FROM 1 PM MONDAY TO 8 PM PDT TUESDAY FOR  
COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER  
AND OUT TO 30 NM.  
 

 
 

 
 
PUBLIC...JAD/MAXWELL  
AVIATION/MARINE/BEACHES...JMB  
 
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