Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 281650
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
945 AM PDT TUE JUL 28 2015

.SYNOPSIS... HIGH PRESSURE BUILDING WESTWARD INTO CALIFORNIA WILL
BRING WARMER DAYS...HIGHER HUMIDITIES AND A SHALLOWER MARINE LAYER
THROUGH FRIDAY. INCREASING MONSOONAL MOISTURE WILL BRING SCATTERED
AFTERNOON AND EVENING THUNDERSTORMS WEDNESDAY THROUGH SUNDAY OVER
THE MOUNTAINS AND DESERTS...SOME OF WHICH MAY DRIFT INTO THE INLAND
VALLEYS.

&&

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

NO CHANGES TO CURRENT FORECAST THIS MORNING. AWAITING THE ARRIVAL OF
THE MONSOON WHICH WILL BEGIN IN EARNEST ON WEDNESDAY AND CONTINUE
WITH VARYING DEGREES OF INTENSITY FOR THE NEXT 7-10 DAYS.

THIS MORNING A 594 DM HIGH WAS CENTERED OVER OKLAHOMA. THIS UPPER
HIGH WILL DRIFT WEST OVER NEW MEXICO THURSDAY AND THEN BECOME
ANCHORED OVER THE FOUR CORNERS REGION FRIDAY THROUGH NEXT WEDNESDAY.
SOUTHEAST FLOW AROUND THE UPPER HIGH WILL DRAW MIDLEVEL MONSOONAL
MOISTURE INTO THE SOUTHWEST. THE FIRST SIGNS OF THIS MONSOONAL SURGE
ARE SHOWING UP IN THE SATELLITE DERIVED PRECIPITABLE WATER VALUES
OVER ARIZONA THIS MORNING. YESTERDAY THE PWAT AT TEMPE WAS AROUND 1
INCH. THIS MORNING IT HAD RISEN TO 1.5 INCHES. CLOSER TO HOME THE
PWAT`S IN THE COACHELLA VALLEY WERE STILL WELL BELOW AN INCH THIS
MORNING BUT WILL TREND UPWARD OVER THE 24-36 HOURS AND APPROACH
1.30" IN THE LOWER DESERTS BY WEDNESDAY EVENING. MUCAPE INCREASES TO
500 J/KG WEDNESDAY AFTERNOON OVER THE MOUNTAINS WHERE THUNDERSTORMS
ARE MOST LIKLEY. SOUTHEAST MIDLEVEL WINDS OF 15-20 KT WILL PUSH THE
STORMS TOWARD THE NORTHWEST...SO SOME STORMS MAY DRIFT INTO THE
INLAND VALLEYS.

PWATS ARE EVEN HIGHER ON THURSDAY...INCREASING TO 1.75"...SO THE
THUNDERSTORM COVERAGE SHOULD BE GREATER. THE STEERING FLOW ALOFT
REMAINS SOUTHEASTERLY SO STORMS MAY ONCE AGAIN DRIFT INTO THE
VALLEYS. THE ELSINORE CONVERGENCE ZONE LOOKS PRIMED TO TRIGGER T-
STORMS IN THE INLAND EMPIRE THURSDAY AFTERNOON WHEN MOISTURE AND
CONVERGENCE PARAMETERS ARE MAXIMIZED.

FRIDAY AND SATURDAY...PWATS DECREASE SLIGHTLY AND THUNDERSTORM
COVERAGE SHOULD BE LESS WIDESPREAD. SOUTHERLY STEERING FLOW WILL
KEEP THE CONVECTION MOSTLY CONFINED TO THE MOUNTAINS AND DESERTS.

SUNDAY THROUGH WEDNESDAY...THE MONSOONAL FLOW PATTERN WILL PERSIST
THROUGH AT LEAST THE MIDDLE OF NEXT WEEK WITH DIURNAL AFTERNOON AND
EVENING THUNDERSTORMS MAINLY OVER THE MOUNTAINS AND DESERTS EACH
DAY.

THE MARINE LAYER WILL TURN SHALLOWER THIS WEEK AS THE UPPER HIGH
BUILDS. 500 MB HTS OVER SAN DIEGO THIS MORNING WERE 589DM...AND THEY
WILL INCREASE TO 592 DM BY THE WEEKEND. WARMING ALOFT WILL INCREASE
THE INVERSION STRENGTH WHICH IN TURN MAY RESULT IN SLOWER CLEARING
OF THE LOW CLOUDS AT THE COAST. HUMIDITIES NEAR THE COAST WILL
SLOWLY INCREASE THROUGH THE END OF THE WEEK BUT IT DOES NOT APPEAR
THAT IT WILL BE AS OPPRESSIVELY HUMID AS IT WAS WHEN THE REMNANT
MOISTURE FROM DOLORES SURGED INTO SO-CAL.

&&

.AVIATION...

281530Z...COAST/VALLEYS...STRATUS WAS LATE TO DEVELOP THIS
MORNING...BUT A SUNRISE SURGE PUSHED LOW CLOUDS WITH BASES 1200-1500
FT MSL AROUND 15-20 MI INLAND. STRATUS WILL ERODE TO THE COAST BY
17Z...RETURNING TO THE COASTAL AIRPORTS 29/06-09Z AND SPREADING 15-
20 MI INLAND OVERNIGHT. BASES WILL BE SLIGHTLY LOWER
TONIGHT...GENERALLY AROUND 1000-1400 FT MSL. OTHERWISE...INCREASING
CLOUDS AOA 15000 FT MSL EARLY WED MORNING WITH UNRESTRICTED VIS.

MTNS/DESERTS...INCREASING CLOUDS AOA 15000 FT MSL EARLY WED MORNING
AND UNRESTRICTED VIS PREVAILING.

&&

.MARINE... 830 AM...THERE IS A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS OVER THE COASTAL WATERS WEDNESDAY NIGHT THROUGH EARLY
THU AFTERNOON AND AGAIN LATE THU NIGHT INTO FRI MORNING.
OTHERWISE...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH SATURDAY.

&&

.BEACHES... 830 AM...THERE IS A SLIGHT CHANCE OF THUNDERSTORMS AT
THE BEACHES WEDNESDAY NIGHT INTO EARLY THU AFTERNOON AND AGAIN LATE
THU NIGHT INTO FRI MORNING...THOUGH EXACT TIMING IS UNCERTAIN.
LIGHTNING WILL POSE A THREAT TO BEACHGOERS SHOULD ANY THUNDERSTORMS
DEVELOP.

&&

.SKYWARN... SKYWARN ACTIVATION MAY BE REQUESTED WEDNESDAY AND
THURSDAY.

&&

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

$$

PUBLIC...MOEDE
AVIATION/MARINE...TS


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