Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 260406
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
905 PM PDT FRI JUL 25 2014

.SYNOPSIS...
HIGH PRESSURE TO THE EAST WILL BRING SEASONALLY WARM SUMMER WEATHER
THROUGH NEXT WEEK. MONSOONAL MOISTURE WILL BRING PERIODS OF ISOLATED
TO SCATTERED THUNDERSTORMS THIS WEEKEND OVER THE MOUNTAINS AND
DESERTS IN THE AFTERNOONS AND EARLY EVENINGS...WITH SMALLER CHANCES
FOR THUNDERSTORMS ON MONDAY. THE MARINE LAYER WILL KEEP COASTAL
AREAS COOLER WITH AREAS OF NIGHT AND MORNING LOW CLOUDS AND FOG
EXTENDING INTO THE WESTERN VALLEYS. THE MARINE LAYER WILL BECOME
MORE SHALLOW STARTING TUESDAY...WITH NIGHT AND MORNING CLOUDS MAINLY
IN THE COASTAL AREAS.

&&

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

AN UPPER LEVEL WAVE MOVING THROUGH SOUTHERN CALIFORNIA FROM SOUTH TO
NORTH BROUGHT NUMEROUS HIGH-BASED SHOWERS AND ISOLATED THUNDERSTORMS
THIS MORNING...WITH MOST AFTERNOON AND EARLY EVENING
SHOWER/THUNDERSTORM ACTIVITY BEING INDUCED BY SURFACE HEATING AND
MOUNTAIN-TOP CONVERGENCE/DESERT CONVERGENCE BOUNDARIES. DUE TO THE
PLETHORA OF MID AND HIGH CLOUDS TODAY...MAX TEMPERATURES WERE
SEVERAL DEGREES LOWER TODAY THAN THEY WERE YESTERDAY...WITH THE
LOWER DESERTS TOPPING OUT ONLY IN THE MID 100S OR SO.

WITH THE WAVE HAVING MOVED NORTH...MOST OF THE UPPER LEVEL LIFT AND
DYNAMICS PROVIDED BY IT HAVE LEFT AS WELL. ALTHOUGH NAM12 AND LOCAL
WRF INDICATE GOOD UPPER LEVEL INSTABILITY OVERNIGHT TONIGHT...BOTH
MODELS DO NOT SHOW ANY FEATURE THAT WILL TRIGGER NOCTURNAL
CONVECTION. HOWEVER...HAVE LEFT A SLIGHT CHANCE OF THUNDERSTORMS FOR
THE MOUNTAINS JUST IN CASE THE MESOSCALE CONVECTIVE COMPLEX OVER
SOUTHERN ARIZONA SENDS OUT AN OUTFLOW BOUNDARY AT OUR AREA WHICH
WOULD PROVIDE A POTENTIAL TRIGGER FOR MOUNTAIN THUNDERSTORMS DURING
THE NIGHT.

MEANWHILE...MARINE LAYER STRATUS SHOULD MAKE IT BACK INTO THE
COASTAL AND WESTERN VALLEY AREAS TONIGHT THROUGH MID-TOMORROW
MORNING...WITH THE WRF SHOWING A DEPTH OF 2000 FEET WHICH IS SIMILAR
TO WHAT IT WAS THIS MORNING.

CURRENTLY...A WEST TO EAST ORIENTED RIDGE OVER NEW MEXICO AND NORTH
TEXAS IS WHAT IS BRINGING THE SOUTHERLY MONSOON SURGE INTO THE
AREA...ALTHOUGH GPS MET PRECIPITABLE WATER SENSORS INDICATE THAT
VALUES HAVE LOWERED TO AROUND 1.4-1.7 INCHES THIS EVENING...WHERE
THEY WERE AT 2 INCHES EARLIER FOR THE DESERTS. IN FACT...PALM
SPRINGS EVEN REPORTED A DEW POINT OF 80 DEGREES AT AROUND 3 PM!
SOUTH TO SOUTHEASTERLY FLOW ALOFT WILL CONTINUE THROUGH
MONDAY...RESULTING IN MONSOONAL MOISTURE CONTINUING TO MOVE INTO THE
AREA...WITH PRECIPITABLE WATER VALUES OF 1.3-1.6 INCHES EACH DAY.
THIS...IN ADDITION TO INSTABILITY PROVIDED BY SURFACE
HEATING...SHOULD BRING A CHANCE OF THUNDERSTORMS TO THE MOUNTAINS
AND DESERTS SATURDAY AFTERNOON/EARLY EVENING AND SUNDAY
AFTERNOON/EARLY EVENING. CHANCES FOR THUNDERSTORMS MAY BE A LITTLE
HIGHER ON SUNDAY WHEN THE GFS...ECMWF AND NAM SHOW AN EASTERLY WAVE
MOVING INTO THE AREA WHICH WOULD ENHANCE LIFT. THIS ALSO COULD SPARK
THUNDERSTORMS DURING THE OVERNIGHT HOURS SUNDAY NIGHT AS WELL.

THE FLOW ALOFT WILL BECOME MAINLY SOUTHERLY ON MONDAY AS THE RIDGE
ORIENTS ITSELF IN A NORTH-TO-SOUTH FASHION...WITH THE GFS AND SREF
SHOWING PRECIPITABLE WATER VALUES LOWERING TO AROUND 1 INCH.
STILL...THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS
FOR MONDAY AFTERNOON/EARLY EVENING. FOR TUESDAY THROUGH AT LEAST
WEDNESDAY...DRY SOUTHWEST FLOW SHOULD GREATLY DIMINISH MONSOON
THUNDERSTORM CHANCES. GFS INDICATES SOME CHANCE FOR A RETURN OF
MONSOONAL FLOW ON THURSDAY...BUT OTHER THAN THAT...IT REMAINS DRY
FOR THE MOST PART. MEANWHILE...THE ECMWF SHOWS DRY AIR TUESDAY
THROUGH FRIDAY.

THE MARINE LAYER WILL GENERALLY REMAIN AT A SIMILAR DEPTH THROUGH
THE NEXT FEW DAYS AS 500 MB HEIGHTS DO NOT CHANGE MUCH...AND
ONSHORE FLOW REMAINS STEADY AS WELL. THUS...EXPECT NIGHT AND MORNING
STRATUS TO CONTINUE TO DEVELOP IN THE COASTAL AND WESTERN VALLEY
SECTIONS...WITH MINOR DAY-TO-DAY VARIATIONS. THE MARINE LAYER MAY
BECOME SHALLOWER STARTING AROUND TUESDAY. DAY-TIME HIGH TEMPERATURES
WILL LIKELY CONTINUE AT GENERALLY NEAR NORMAL THROUGH NEXT
WEEK...ALTHOUGH THE ECMWF SHOWS 850 MB TEMPERATURES INCREASING
TUESDAY THROUGH THURSDAY...WHICH COULD BRING HIGHER TEMPERATURES
THAN EXPECTED.

&&

.AVIATION...
260300Z...COAST/VALLEYS...STRATUS WITH BASES FROM 1200-1500 FT OVER
THE COASTAL WATERS MOVING EAST AND ARRIVING AT THE COASTAL AIRPORTS
BTWN 06-09Z. CLEARING SATURDAY BY 17Z SAT. SCT-BKN CLOUDS AT/ABOVE
10000 FT MSL.

MTNS/DESERTS...SCT-BKN080-100 TONIGHT. SOUTHEAST MONSOONAL FLOW WILL
BRING ANOTHER CHANCE FOR THUNDERSTORMS SATURDAY.

&&

.MARINE...
800 PM PDT...NO HAZARDOUS MARINE WEATHER THROUGH WEDNESDAY.

&&

.SKYWARN...
SPOTTER ACTIVATION MAY BE NEEDED SATURDAY.

&&

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

PZ...NONE.

&&

$$

PUBLIC...HARRISON
AVIATION/MARINE...MOEDE





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