000
FXUS66 KSGX 081605
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
905 AM PDT WED AUG 8 2018

.SYNOPSIS...
NOT QUITE AS HOT TODAY AS MONSOONAL MOISTURE SLOWLY INCREASES AND
HIGH PRESSURE ALOFT BEGINS TO SHIFT NORTHWARD. THAT MONSOONAL
MOISTURE IS EXPECTED TO BRING ISOLATED THUNDERSTORMS NEAR THE
MOUNTAINS THIS AFTERNOON AND SCATTERED THUNDERSTORMS ON THURSDAY
WITH A SLOW DECREASE ON FRIDAY AND GREATER DECREASE ON SATURDAY.
A RETURN OF ONSHORE FLOW AND DRYING OF THE MONSOONAL MOISTURE IS
EXPECTED FOR THE WEEKEND THROUGH EARLY NEXT WEEK WITH HIGH
TEMPERATURES RETURNING TO NEAR TO SLIGHTLY ABOVE AVERAGE AND LOW 
TEMPERATURES REMAINING ABOVE AVERAGE.

&&

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

A GULF SURGE ENVELOPED THE LOWER DESERTS THIS MORNING, PRODUCING
IMPRESSIVE DEW POINTS THAT TOUCHED 80 DEGREES, LOW CLOUDS AND EVEN
PATCHY DRIZZLE. IN FACT, THERE WERE MORE LOW CLOUDS IN THE DESERT
THAN THERE WERE ALONG THE COAST! INSTABILITY AND MONSOON MOISTURE
ARE UP TODAY AS SEEN BY THE GULF SURGE AND A FEW ALTOCUMULUS 
CLOUDS THAT ACCENTED OUR SUNRISE THIS MORNING. TEMPERATURES WILL 
BE DOWN TODAY A FEW DEGREES AS THIS MOISTURE COMES UP. SMOKE FROM 
THE HOLY FIRE ON SANTIAGO PEAK WILL CONTINUE TO FILL SKIES IN THE 
NORTHWEST INLAND EMPIRE. WE ARE LOOKING AT ISOLATED THUNDERSTORMS
IN THE MOUNTAINS THIS AFTERNOON. HURRICANE JOHN IS FORECAST TO
WEAKEN FROM HURRICANE TODAY TO TROPICAL STORM ON THURSDAY. THE
MAIN IMPACT ON US FROM JOHN WILL BE THAT HE WILL HELP THE 
SOUTHEAST MONSOON FLOW TO CONTINUE THROUGH ABOUT FRIDAY. THE
MONSOON MOISTURE DEEPENS THURSDAY INTO FRIDAY FOR A BETTER CHANCE
OF THUNDERSTORMS MAINLY IN THE MOUNTAINS AND MAINLY IN THE
AFTERNOONS. THE DEEPER MOISTURE WILL INCREASE THE POTENTIAL FOR 
ISOLATED FLASH FLOODS. SOME MODEL GUIDANCE IS HINTING 
INTERMITTENTLY THAT SOME NOCTURNAL WAVE OR OUTFLOW FROM ARIZONA 
THUNDERSTORMS COULD MOVE INTO OUR REGION DURING THE NIGHTS TONIGHT
AND THURSDAY NIGHT. THIS KEEPS OUR ATTENTION FOR THE POSSIBILITY 
OF NOCTURNAL SHOWERS OR THUNDERSTORMS AND EVEN WEST OF THE 
MOUNTAINS. HOWEVER, LATEST GUIDANCE SEEMS TO DOWNPLAY THAT 
SCENARIO, BUT ITS STILL ON OUR (AHEM) RADAR. THE EASTERLY FLOW 
DOES LOOK TO BOOST TEMPS A BIT WEST OF THE MOUNTAINS ON THURSDAY,
AS WELL AS THE POSSIBILITY OF A FEW THUNDERSTORMS DRIFTING INTO
INLAND VALLEYS. LATER FRIDAY AND SATURDAY THE FLOW TURNS MORE 
WESTERLY, WHICH WILL DECREASE THE MONSOON MOISTURE AND 
THUNDERSTORM CHANCES OVER THE WEEKEND. TEMPERATURES WILL DECREASE 
OVER THE SAME TIME PERIOD, BUT MAX TEMPS IN MOST AREAS WILL REMAIN
A COUPLE DEGREES ABOVE AVERAGE. STILL, NEAR NORMAL WILL FEEL LIKE
RELIEF. IN ADDITION, COASTAL LOW CLOUDS SHOULD BE ABLE TO DEVELOP
AND SURVIVE THE NIGHTS. THIS WILL BE THE CASE THROUGH SATURDAY 
THROUGH MONDAY AS WE GET A BREAK FROM EXTREME HEAT AND 
THUNDERSTORMS. FOR TUESDAY AND BEYOND, MODEL GUIDANCE FEATURES 
STRENGTHENING HIGH PRESSURE ALOFT FOR WARMER WEATHER AND AN 
INCREASE IN MONSOON MOISTURE FOR A BETTER CHANCE OF THUNDERSTORMS.
BACK TO THE NEW NORMAL.

&&

.AVIATION... 
081600Z...COASTS/VALLEYS...MOSTLY CLEAR SKIES WILL PREVAIL THROUGH 
THIS EVENING. VIS WILL BE UNRESTRICTED EXCEPT WHERE SMOKE CAUSES 2-5 
MILE VIS AT TIMES OVER PORTIONS OF THE INLAND EMPIRE IN RIVERSIDE 
AND SAN BERNARDINO COUNTIES. PATCHY STRATUS WILL DEVELOP LATE ALONG 
THE COAST WITH LOCAL CIGS 600-900 FT MSL AND LOCAL VIS 2-4 MILES 
OVER HIGHER COASTAL TERRAIN. SAN/CRQ COULD HAVE TEMPO CIGS BETWEEN 
10Z AND 15Z THU. MOST AREAS WILL CLEAR BY 15Z THU.

MOUNTAINS/DESERTS...AREAS OF BKN CLOUDS AROUND 3000 FT MSL AND VIS 
AROUND 5 MILES WILL CONTINUE THROUGH 17Z IN THE COACHELLA VALLEY. 
THERE IS ALSO A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS 
AND HIGH DESERTS THIS AFTERNOON AND EVENING, WITH CLOUD BASES 9000-
10000 FT MSL AND TOPS TO 30000 FT MSL AND STRONG UP/DOWNDRAFTS AND 
SURFACE GUSTS TO 35 KT.

&&

.MARINE...
NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH SUNDAY.

&&

.BEACHES...
EVENING HIGH TIDES WILL RISE TO AROUND 7 FT THURSDAY THROUGH 
SATURDAY. IN ADDITION, SOUTH SWELLS GENERATED FROM HURRICANE JOHN 
WILL MOVE INTO THE COASTAL WATERS LATE THURSDAY AND CONTINUE THROUGH 
THE WEEKEND. THE COMBINATION OF HIGH TIDES AND INCREASING SURF OF 3-
5 FT (MAINLY SOUTH/SOUTHWEST FACING BEACHES) WILL LIKELY CAUSE MINOR 
COASTAL FLOODING DURING THE LATE AFTERNOON AND EVENING EACH OF THESE 
DAYS. LARGE TIDAL SWINGS AND ELEVATED SURF WILL ALSO GENERATE STRONG 
RIP CURRENTS. 

&&

.FIRE WEATHER...
THE RECOVERY IN HUMIDITY WILL CONTINUE TODAY AS MONSOONAL
MOISTURE SLOWLY INCREASES. HOWEVER...HUMIDITIES WILL STILL FALL TO
AROUND 10 PERCENT IN PORTIONS OF THE APPLE AND LUCERNE VALLEYS,
AND 15 TO 20 PERCENT IN PORTIONS OF THE SANTA ANA MOUNTAINS AND
INLAND EMPIRE. THE CONTINUED INFLUX OF MOISTURE WILL BRING A
GREATER RECOVERY ON THURSDAY. A FEW ISOLATED THUNDERSTORMS ARE
EXPECTED NEAR THE MOUNTAINS THIS AFTERNOON, WITH SCATTERED
THUNDERSTORMS THURSDAY AFTERNOON AND EARLY EVENING FOR THE
MOUNTAINS AND PORTIONS OF THE DESERTS.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...BEACH HAZARDS STATEMENT FROM THURSDAY EVENING THROUGH SATURDAY 
     EVENING FOR ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY 
     COASTAL AREAS.

PZ...NONE.

&&

$$

PUBLIC...MM
AVIATION/MARINE/BEACHES...MAXWELL
FIRE WEATHER...17

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