Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 300437
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PDT MON JUN 29 2015

.SYNOPSIS...
SOUTHEAST FLOW ALOFT WILL CONTINUE TO BRING MOISTURE INTO SOUTHERN
CALIFORNIA AND BRING SLIGHT CHANCES OF THUNDERSTORMS...MAINLY TO THE
MOUNTAINS AND MAINLY DURING THE AFTERNOONS THROUGH THURSDAY. A HIGH
PRESSURE RIDGE CENTERED OVER UTAH AND WEAK ONSHORE FLOW WILL KEEP
TEMPERATURES ABOVE NORMAL THROUGH WEDNESDAY...THEN AS ONSHORE FLOW
STRENGTHENS LATE IN THE WEEK...THERE WILL BE A COOLING TREND. DRY
WEATHER WILL RETURN FRIDAY OR SATURDAY AND CONTINUE THROUGH THE
WEEKEND AS THE MOISTURE ALOFT DECREASES. COASTAL LOW CLOUDS WILL
GRADUALLY INCREASE THE REST OF THIS WEEK.

&&

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

SKIES HAD MOSTLY CLEARED EARLY THIS EVENING AFTER ISOLATED SHOWERS
AND THUNDERSTORMS OCCURRED THIS AFTERNOON. CLOUDS SHOULD INCREASE
AGAIN OVERNIGHT AS DEBRIS CLOUDS MOVE WEST FROM THE THUNDERSTORMS
THAT OCCURRED OVER ARIZONA TODAY/THIS EVENING. STRATUS SHOULD BE
SOMEWHAT LIMITED AND DEVELOP LATE...BUT WITH FEWER CLOUDS ALOFT AND
SOMEWHAT STRONGER ONSHORE FLOW...THERE SHOULD BE A LITTLE MORE THAN
LAST NIGHT/THIS MORNING.

SOUTHEAST FLOW WILL CONTINUE TO BRING MID AND HIGH LEVEL MOISTURE TO
THE REGION IN THE 700-400 MB RANGE...SOMETIMES HIGHER. THERE WILL BE
QUITE A LOT OF HIGH CLOUDINESS TO CUT DOWN ON INSTABILITY IN THE
MOUNTAINS AND DESERTS...BUT THERE SHOULD BE ENOUGH FOR AT LEAST A
FEW THUNDERSTORMS. HOWEVER...THE DRY LAYER BETWEEN 950 MB AND 700 MB
WILL RESULT IN EVAPORATION OF A LOT OF THE PRECIP...AND WINDS OF 20-
25 KNOTS...SOMETIMES HIGHER...WILL RESULT IN RAPID MOVEMENT OF THE
CELLS. THUS...PRECIP AMOUNTS WILL GENERALLY BE LOW...WITH ONLY VERY
ISOLATED LOCATIONS GETTING ONE-QUARTER INCH OR MORE. BEST CHANCES
WILL BE IN THE AFTERNOON...THOUGH WITH SOME PERIODIC ELEVATED MUCAPE
IN THE 700-500 MB LAYER...A NOCTURNAL STORM IS NOT OUT OF THE
QUESTION...MAINLY TOWARDS MID-WEEK. FOR TUESDAY...BEST SURFACE
CONVERGENCE OCCURS OVER THE MOUNTAINS...WHICH MEANS HIGHER MOUNTAIN
TERRAIN WILL HAVE THE BEST CHANCE OF PRECIP. HOWEVER...THE TREND FOR
WED AND ESPECIALLY THU WITH THE STRONGER ONSHORE FLOW WILL MEAN THAT
SURFACE CONVERGENCE WILL BE STRONGEST IN THE DESERTS WHICH IS NOT AS
FAVORABLE FOR MOUNTAIN STORMS. ALSO...IT WILL BECOME FAIRLY WINDY
THROUGH SAN GORGONIO PASS AND ON THE DESERT MOUNTAIN SLOPES STARTING
LATE WED DUE TO THE STRONGER ONSHORE FLOW.

BY THE WEEKEND...WE SHOULD DRY OUT AS THE FLOW WILL BE MORE
SOUTHERLY OR EVEN A BIT SOUTHWESTERLY INSTEAD OF EAST-SOUTHEASTERLY.
ONSHORE FLOW SHOULD BE FAIRLY STRONG...THOUGH RIDGING WILL CONTINUE
INLAND...SO TEMPS WILL BE NEAR NORMAL...EXCEPT A LITTLE BELOW NORMAL
NEAR THE COAST WHERE THE MARINE LAYER WILL PREVAIL. ECMWF HAS
MONSOONAL MOISTURE RETURNING EARLY NEXT WEEK...BUT GFS HAS THAT
DELAYED UNTIL MID-WEEK. FOR NOW...I WILL KEEP EARLY NEXT WEEK DRY.

&&

.AVIATION...
300315Z...COAST/VALLEYS...SCT-BKN CLOUDS AOA 10000 FT MSL THROUGH
TUE. AREAS OF MARINE STRATUS REDEVELOPING LATE AFT 09Z THROUGH 14Z
TUE EXTENDING LOCALLY INLAND 5-10 SM...MAINLY SAN DIEGO COUNTY
COAST. BASES ARE EXPECTED TO BE 800 TO 1200 FT MSL WITH TOPS BLO
1500 FT MSL. THE STRATUS DECK WILL DISSIPATE BEFORE 18Z. CONFIDENCE
IN TIMING/OCCURRENCE IS LOW AND LOWER CLOUDS ARE NOT EXPECTED TO
REACH KSNA.

MTNS/DESERTS...SCT-BKN CLOUDS AOA 10000 FT MSL THROUGH TUE. CU/TCU
DEVELOPING AFT 18Z THROUGH 22Z WITH ISOLATED -SHRA/TSRA AND TOPS TO
NEAR FL300. LOCAL GUSTY DOWNDRAFT WINDS MAY RESULT IN STRONG SFC
WIND GUSTS AND LLWS WITH LOCAL VIS RESTRICTIONS IN BLOWING DUST.

&&

.MARINE...
845 PM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH FRIDAY.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&

$$

PUBLIC...MAXWELL
AVIATION/MARINE...JAD



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