Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 260956
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
256 AM PDT SAT JUL 26 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
YESTERDAY MORNING...WITH MOST AFTERNOON AND EARLY EVENING
SHOWER/THUNDERSTORM ACTIVITY BEING INDUCED BY SURFACE HEATING AND
MOUNTAIN-TOP CONVERGENCE/DESERT CONVERGENCE BOUNDARIES.

MEANWHILE...MARINE LAYER STRATUS IS SLOWLY DEVELOPING ALONG THE
COAST...AND SHOULD BE AT A DEPTH OF AROUND 2000 FEET AGAIN THIS
MORNING. STRATUS SHOULD CLEAR BACK TO THE COAST BY LATE
MORNING...ALTHOUGH HIGH CLOUDS WILL CONTINUE TO BRING PARTLY TO
MOSTLY CLOUDY SKIES TO THE COAST AND VALLEYS.

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 1.3-1.6 INCHES THIS MORNING...WHERE
THEY WERE AT 2 INCHES YESTERDAY AFTERNOON IN THE DESERTS. IN
FACT...PALM SPRINGS EVEN REPORTED A DEW POINT OF 80 DEGREES AT
AROUND 3 PM YESTERDAY! 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 FURTHER. THIS ALSO
COULD SPARK THUNDERSTORMS DURING THE OVERNIGHT HOURS SUNDAY NIGHT AS
WELL. THIS MAY NEED TO BE ADDED TO THE FORECAST IF CONFIDENCE GROWS
WITH FUTURE MODEL RUNS.

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 MOSTLY 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 ACCORDING TO THE GFS.
DAY-TIME HIGH TEMPERATURES WILL LIKELY CONTINUE AT GENERALLY NEAR
NORMAL THROUGH NEXT WEEK...WITH A BRIEF PERIOD OF SLIGHTLY WARMER
CONDITIONS TUESDAY THROUGH WEDNESDAY.

&&

.AVIATION...
260900Z...COAST/VALLEYS...AREAS OF STRATUS WITH BASES FROM 800-1200
FT AND TOPS OF 1600 FT OVER THE COASTAL WATERS EXTENDING INLAND
ACROSS THE ORANGE COUNTY PLAIN AND AROUND 15 MILES INLAND IN SAN
DIEGO COUNTY WITH LOCAL VISIBILITY OF 3 TO 5 MILES IN FOG...CLEARING
BY 17Z. SCT-BKN CLOUDS AT/ABOVE 10000 FT MSL. COASTAL STRATUS WILL
GRADUALLY RETURN FOR COASTAL AIRPORTS INCLUDING KCRQ AND KSAN
BETWEEN 27/0400Z-0800Z WITH SIMILAR BASES AND TOPS AS THIS MORNING.

MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS WILL OCCUR THIS
AFTERNOON/EARLY THIS EVENING...MOST NUMEROUS IN RIVERSIDE AND SAN
DIEGO COUNTIES. A THUNDERSTORM COULD REACH KPSP...WITH GREATEST
THREAT BEING LIGHTNING. LOCAL VIS OF 3 MI WILL OCCUR WITH HEAVIER
SHOWERS. BASES OF THE BKN-OVC CLOUDS WILL BE AT/ABOVE 8000 FT WITH
ISOLATED TOPS TO 35000 FT MSL.

&&

.MARINE...
200 AM PDT...NO HAZARDOUS MARINE WEATHER THROUGH WEDNESDAY.

&&

.SKYWARN...
SPOTTER ACTIVATION WILL PROBABLY NOT BE NEEDED TODAY.

&&

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

&&

$$

PUBLIC...HARRISON
AVIATION/MARINE...17




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