017  
FXUS66 KSGX 050330  
AFDSGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SAN DIEGO CA  
830 PM PDT SAT OCT 4 2025  
   
SYNOPSIS  
 
MILD, NEAR TO BELOW NORMAL TEMPERATURES WITH LITTLE DAY TO DAY  
CHANGE THROUGH MONDAY, FOLLOWED BY A GRADUAL WARMING TREND INTO  
THE MIDDLE/LATTER PART OF NEXT WEEK. DAILY MARINE LAYER CLOUDS WILL  
LIKELY MAKE A COMEBACK EARLY SUNDAY MORNING, WITH MORE WIDESPREAD  
LOW CLOUDS NEXT WEEK. PERIODS OF WEAK OFFSHORE WINDS OVERNIGHT  
AND IN THE MORNINGS OVER MOUNTAIN RIDGES AND IN THE DESERTS WILL  
OCCUR THROUGH EARLY NEXT WEEK. THERE IS THE POTENTIAL FOR TROPICAL  
MOISTURE TO MOVE INTO THE AREA LATE IN THE WEEK, BRINGING A  
SLIGHT CHANCE OF SHOWERS, MOST LIKELY OVER THE MOUNTAINS BUT WITH  
THE POTENTIAL FOR MORE WIDESPREAD ACTIVITY.  
 
 
   
DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE  
 
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO  
COUNTIES...  
   
EVENING UPDATE  
 
PATCHY LOW CLOUDS CONTINUE TO DEVELOP OFFSHORE THIS EVENING. THESE  
WILL SLOWLY INCREASE IN COVERAGE OVERNIGHT WITH SOME CLOUD COVER  
LINGERING INTO THE MORNING NEAR THE COAST BEFORE CLEARING  
THEREAFTER. CALM CONDITIONS WILL CONTINUE THROUGH THE MIDDLE OF  
THE WEEK. WE CONTINUE TO WATCH TROPICAL STORM PRISCILLA TO THE  
SOUTH. THERE REMAINS GREAT UNCERTAINTY ON THE EXACT TRACK OF THIS  
SYSTEM. THE SYNOPTIC SET UP WILL BE KEY AS LOW PRESSURE TO THE  
NORTH AND HIGH PRESSURE TO THE SOUTH WILL DICTATE THE SYSTEM'S  
PATH EITHER TOWARD OUR REGION OUR OR OUT TO SEA. KEEP AN EYE ON  
THE FORECAST OVER THE COMING DAYS AND READ BELOW FOR MORE DETAILED  
INFORMATION.  
   
PREVIOUS DISCUSSION (149 PM SATURDAY)  
 
   
SHORT TERM  
 
A BROAD TROUGH WILL REMAIN OVER THE WESTERN U.S. INTO EARLY NEXT  
WEEK, AND A SHORTWAVE DIGGING DOWN THE WESTERN SIDE OF THE TROUGH  
WILL DEVELOP INTO A WEAK LOW OFF THE SOUTH-CENTRAL CALIFORNIA  
COAST. THIS WILL RESULT IN A VERY SUBTLE COOLING WEST OF THE  
MOUNTAINS AND SUBTLE WARMING FOR THE MOUNTAINS AND DESERTS SUNDAY  
THROUGH MONDAY, BUT IN PRACTICE TEMPERATURES WILL STILL FEEL VERY  
SIMILAR TO TODAY. HOWEVER, THE LOW WILL BRING NIGHTLY AND MORNING  
LOW CLOUDS BACK TO OUR COASTAL AREAS. LOW CLOUDS WILL STRUGGLE TO  
FORM FOR MOST OF TONIGHT, BUT AN EDDY CIRCULATION DEVELOPING  
EARLY SUNDAY MORNING WILL MOISTEN THINGS UP ENOUGH TO GET AT LEAST  
PATCHY LOW CLOUDS ALONG THE SAN DIEGO AND LIKELY NORTHERN ORANGE  
COUNTY COASTLINE. LOW CLOUDS SUNDAY AND MONDAY NIGHTS WILL BE  
EARLIER TO DEVELOP IN THE EVENING AND MORE WIDESPREAD OVERNIGHT.  
 
MEANWHILE, A SHORTWAVE TROUGH MOVING INTO THE INTERMOUNTAIN WEST  
WILL LEAD TO SOME WEAKLY BREEZY OFFSHORE FLOW FROM THE EAST TO  
NORTHEAST FOR THE MOUNTAINS AND DESERTS FROM THE EARLY MORNING  
THROUGH EARLY TO MID-AFTERNOON BOTH MONDAY AND TUESDAY. THESE  
WINDS AREN'T STRONG ENOUGH FOR ANY MAJOR IMPACTS, BUT WILL LEAD TO  
DRIER CONDITIONS IN THESE AREAS THAN PAST DAYS.  
 
 
   
LONG TERM  
 
THE WEAK CLOSED LOW OFF THE SOUTH-CENTRAL COAST WILL MERGE INTO  
THE BROADER TROUGH AND MOVE TO THE NORTHEAST LATE TUESDAY INTO  
WEDNESDAY AS THE WEST END OF A BROAD HIGH OVER THE SOUTHERN U.S.  
NUDGES INTO THE AREA. THIS WILL RESULT IN A WARMING TREND TUESDAY  
THROUGH THE MID TO LATTER HALF OF NEXT WEEK. MEANWHILE, A LARGE  
LOW PRESSURE SYSTEM WILL DROP SOUTH OUT OF THE GULF OF ALASKA AND  
MAKE ITS WAY DOWN THE WEST COAST. SIMULTANEOUSLY, THE DEVELOPING  
TROPICAL SYSTEM PRISCILLA SOUTH OF BAJA CALIFORNIA WILL GRADUALLY  
MAKE ITS WAY NORTHWEST THROUGH NEXT WEEK, LIKELY LEADING TO SOME  
AMOUNT OF REMNANT MOISTURE MOVING INTO SOUTHERN CALIFORNIA BY LATE  
THURSDAY/FRIDAY.  
 
THERE IS SIGNIFICANT DIFFERENCES IN MODEL OUTPUT FOR WHERE THE  
LOW FROM THE NORTHWEST WILL SET UP, AS WELL AS THE TRACK OF THE  
TROPICAL SYSTEM AND HOW MUCH MOISTURE IT WILL ADVECT INTO THE  
AREA. THERE IS THE POSSIBILITY FOR DRY WEATHER TO CONTINUE ALL  
WEEKEND (MOST LIKELY AT THIS MOMENT) AS WELL AS FOR A QUITE WET  
WEEKEND IN SOME AREAS (CURRENTLY AN OUTSIDE CHANCE). THIS IS  
LEADING TO A LOW CONFIDENCE FORECAST FOR TEMPERATURES, WINDS AND  
POSSIBLE CONVECTIVE RAINFALL FOR THE LATTER PART OF NEXT WEEK.  
 
FOR NOW, THE FORECAST IS FOR NEAR THE ZERO CHANCES FOR RAINFALL  
INCREASING TO A SMALL CHANCE (10-15%) BY LATE THURSDAY, FOLLOWED  
BY SLIGHT CHANCES (15-20%) OVER THE MOUNTAINS AND PARTS OF THE  
DESERTS AND LESS THAN 15% CHANCES ELSEWHERE FRIDAY AND SATURDAY.  
ANY MOISTURE WOULD BE FAIRLY ELEVATED AT FIRST, RESULTING IN  
THOSE HIGHER CHANCES OVER THE MOUNTAINS, BUT IF WE GET STRONG  
ENOUGH FORCING FROM TROUGHING NEARBY, SHOWERS WEST OF THE  
MOUNTAINS WOULD NOT BE OUT OF THE QUESTION, AS INDICATED BY A  
HANDFUL OF ENSEMBLE MEMBERS. CURRENTLY CHANCES FOR THUNDERSTORMS  
ARE TOO LOW TO INCLUDE IN THE FORECAST.  
 
 
   
AVIATION  
 
050300Z....COASTS/VALLEYS...AS OF 03Z SAT, CLEAR SKIES PREVAIL. LOW  
CLOUDS WITH BASES 1500-2500 FT MSL TO SLOWLY START TO DEVELOP IN  
VERY PATCHY FASHION THROUGHOUT THE COASTAL BASIN. EVENTUALLY, BY 10-  
12Z TONIGHT, CONFIDENCE INCREASES FOR GREATER BKN COVERAGE ACROSS SD  
COUNTY AND COASTAL ORANGE COUNTY. MOST CLOUDS SCATTER OUT TO THE  
COAST 17-19Z WITH A SLIGHT CHANCE FOR OFF-AND-ON SCT-BKN CIGS TO  
LINGER THROUGH THE AFTERNOON AT THE IMMEDIATE SD COUNTY COASTLINE,  
INCLUDING AT KSAN. CLOUDS WITH SIMILAR BASES WILL START TO DEVELOP  
AFTER 00Z MON AT THE COAST, BROADENING IN COVERAGE, AND EVENTUALLY  
FILLING INTO ALL OF SD/ORANGE COUNTY LOWLANDS OVERNIGHT.  
 
MOUNTAINS/DESERTS...VFR CONDITIONS WILL PREVAIL INTO SUN NIGHT.  
 
 
   
MARINE  
 
NO HAZARDOUS MARINE CONDITIONS ARE EXPECTED THROUGH WEDNESDAY.  
 
 
   
SKYWARN  
 
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE  
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.  
 
 
   
SGX WATCHES/WARNINGS/ADVISORIES  
 
CA...NONE.  
PZ...NONE.  
 
 
 
 
 
UPDATE...APR  
PUBLIC...CSP  
AVIATION/MARINE...WESTERINK  
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