Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 310412
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
915 PM PDT SUN AUG 30 2015

.SYNOPSIS... A TROUGH OF LOW PRESSURE WILL DEVELOP NEAR THE WEST
COAST WITH INCREASING ONSHORE FLOW AND A DEEPENING MARINE LAYER
THROUGH MIDWEEK. COOLER MONDAY AND TUESDAY...THEN THERE WILL BE ONLY
MINOR TEMPERATURES VARIATIONS WEDNESDAY THROUGH FRIDAY. GUSTY
AFTERNOON WINDS ARE FORECAST IN THE MOUNTAINS AND DESERTS EACH DAY.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

THE COOLING TREND CONTINUED TODAY WITH HIGH TEMPERATURES 4 TO 8
DEGREES LOWER THAN YESTERDAY. THIS DOWNHILL SLIDE WILL CONTINUE
MONDAY AS A COOLER AIRMASS MOVES INTO SO-CAL ASSOCIATED WITH A
TROUGH OF LOW PRESSURE MOVING IN FROM THE NORTHWEST.

THE MARINE STRATUS THAT HAS BEEN ABSENT THE PAST FEW DAYS WAS
GETTING A FOOTHOLD AT THE COAST THIS EVENING WITH CEILINGS OVER THE
COASTAL WATERS JUST WEST OF CAMP PENDLETON AND OCEANSIDE. THE HIGH
RESOLUTION WRF MODEL SPINS UP A COASTAL EDDY TONIGHT AND THE MARINE
LAYER CLOUD COVER IS FORECAST TO EXPAND AND MOVE ACROSS COASTAL
ORANGE AND SAN DIEGO COUNTIES. BY SUNRISE MONDAY IT LOOKS LIKE IT
WILL BE DEEP ENOUGH TO REACH THE WESTERN VALLEYS.

THIS WEEK WE WILL BE SANDWICHED BETWEEN THE LARGE TROUGH ALONG THE
WEST COAST AND AN UPPER RIDGE CENTERED OVER WEST TEXAS. HEIGHT FALLS
WILL RESULT IN CONTINUED COOLING AND A DEEPER MARINE LAYER THROUGH
WEDNESDAY. ON THURSDAY AND FRIDAY THE UPPER AIR PATTERN BECOMES
QUASI-STATIONARY WITH ONLY MINOR DAY TO DAY VARIATIONS IN
TEMPERATURES. IT WILL BE WINDY IN THE AFTERNOONS AND EVENINGS IN THE
MOUNTAIN PASSES AND DESERTS THIS WEEK.

LONG RANGE OUTLOOK FOR NEXT WEEKEND....IN THE TROPICS...A
DISTURBANCE 650 MILES SOUTH-SOUTHWEST OF MANZANILLO MEXICO HAS A 70%
CHANCE OF DEVELOPING INTO A TROPICAL DEPRESSION IN THE NEXT 24-48
HOURS. THE LONG RANGE ECMWF AND GFS BRING MOISTURE FROM THIS SYSTEM
NORTHWARD ACROSS CENTRAL BAJA AND INTO THE SOUTHWESTERN U.S. NEXT
WEEKEND. AT THIS TIME THE POSITION OF THE LONG WAVE TROUGH ALONG THE
WEST COAST LOOKS LIKE IT WILL FORCE MOST OF THE MOISTURE EAST OF SO-
CAL AND INTO SONORA MEXICO AND ARIZONA. BUT IF THE WEST COAST TROUGH
WEAKENS OR WINDS UP A LITTLE FARTHER WEST OF ITS CURRENT
POSITION...THEN SOME MID AND HIGH-LEVEL MOISTURE COULD MAKE ITS WAY
INTO SOUTHERN CALIFORNIA NEXT WEEKEND. IT WILL INTERESTING TO SEE
HOW IT UNFOLDS.

&&

.AVIATION...

310400Z...COAST/VALLEYS...AREAS OF BKN/OVC STRATUS WILL SPREAD ALONG
THE COAST THROUGH 07Z...INCLUDING TO KSAN...THEN UP TO 30 MI INLAND
BY 13Z. BASES WILL BE 1200-1500 FT MSL WITH TOPS TO 1800 FT MSL.
THERE IS A SMALL CHANCE STRATUS OR FOG COULD REACH KONT 12-15Z. MOST
VIS WILL REMAIN ABOVE 5 MI...EXCEPT LOCAL VIS 1-3 MI WILL OCCUR IN
THE VALLEYS...INCLUDING VCNTY KRNM AND KCNO. MOST AREAS WILL CLEAR
BY 17Z MONDAY. OTHERWISE...SCT-BKN CLOUDS ABOVE 20000 FT MSL WILL
CONTINUE THROUGH MIDDAY MONDAY. STRATUS WILL SPREAD INLAND MONDAY
EVENING.

MOUNTAINS/DESERTS...SCT-BKN CLOUDS ABOVE 20000 FT MSL WILL CONTINUE
THROUGH MIDDAY MONDAY. VIS WILL BE UNRESTRICTED THROUGH MONDAY
EVENING AND BEYOND. AREAS OF WEST WINDS 15-25 KT WITH GUSTS 30-40 KT
WILL OCCUR THROUGH SAN GORGONIO PASS AND THE DESERT MTN
SLOPES/FOOTHILLS THROUGH 11Z WITH ASSOC UP/DOWNDRAFTS AND LLWS.
WINDS WILL BE SLIGHTLY LESS STRONG MON AFTERNOON/EVENING.

&&

.MARINE...

900 PM...WIND GUSTS AROUND 25 KNOTS WERE OCCURRING AT SAN CLEMENTE
BASIN BUOY...BUT WINDS WILL GRADUALLY DECREASE LATE THIS EVENING AND
OVERNIGHT. A SMALL CRAFT ADVISORY FOR THE OUTER WATERS WILL EXPIRE
AT 2 AM MONDAY.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 2 AM PDT MONDAY FOR WATERS FROM SAN
     MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT
     INCLUDING SAN CLEMENTE ISLAND.

&&

$$

PUBLIC...MOEDE
AVIATION/MARINE...MAXWELL



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