Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 040422
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
922 PM PDT TUE MAY 3 2016

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL SLOWLY APPROACH FROM THE WEST AND
RESULT IN COOLING AND MORE CLOUDS WEDNESDAY...WITH PRECIPITATION
POSSIBLE THURSDAY THROUGH THE WEEKEND. A FEW THUNDERSTORMS COULD
OCCUR...ESPECIALLY FRIDAY WHEN THE SYSTEM IS OVERHEAD. IT WILL BE
COOL THURSDAY THROUGH THE WEEKEND...THEN FAIR WEATHER WITH A
WARMING TREND WILL OCCUR EARLY NEXT WEEK AS A HIGH PRESSURE RIDGE
MOVES IN FROM THE WEST.

&&

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

THE TRANQUIL WEATHER NOW OVER SOUTHERN CALIFORNIA WILL TAKE AN
UNSETTLED TURN AS AN UPPER LOW OVER THE PACIFIC...POSITIONED
NEAR 33N/131W...APPROACHES THE AREA WED-THU AND EVENTUALLY MOVES
OVERHEAD BY FRIDAY.

THE UPPER LOW WILL START TO LOWER HEIGHTS/TEMPS ALOFT OVER SO-CAL
TONIGHT. THAT WILL START TO DEEPEN OUR MARINE LAYER AND RESULT IN
STRATUS BEING MORE LIKELY IN THE VALLEYS IN THE LATE NIGHTS AND
EARLY MORNINGS. THE ONSHORE FLOW WILL INCREASE AND BRING A COOLING
TREND TO MOST AREAS WEST OF THE MOUNTAINS WEDNESDAY. RIGHT
NOW...IT LOOKS LIKE ONLY ENOUGH MOISTURE IN THE MARINE LAYER FOR
DRIZZLE WILL OCCUR WED NIGHT/THU MORNING. SHOWERS COULD START
THURSDAY AFTERNOON AND PEAK FRIDAY WHEN THE UPPER LOW IS RIGHT
OVER US AND THE MOIST LAYER IS DEEPEST...BUT THE LOW WILL MOVE
SLOW ENOUGH THAT SOME SHOWERS COULD OCCUR OVER THE
WEEKEND...ESPECIALLY IN THE MOUNTAINS. THUNDERSTORM CHANCES WILL
BE BEST FRIDAY WITH THE COLD AIR AND THE LOW DIRECTLY OVER
US...WITH 500 MB TEMPS APPROACHING -25 C. A THUNDERSTORM COULD
HAPPEN SAT AFTERNOON AS WELL MAINLY OVER THE MOUNTAINS. AS THE SUN
ANGLE IS HIGH ENOUGH TO RESULT IN INSTABILITY FROM DAYTIME
HEATING...EVEN THOUGH THERE WILL BE A LITTLE LESS COLD AIR ALOFT.
AT OTHER TIMES...WE WILL RELY ON THE ONSHORE FLOW CAUSING LIFTING
OF A LOW- LEVEL NEAR-SATURATED LAYER OVER THE TERRAIN TO BRING
SOME PRECIPITATION. PRECIP AMOUNTS ARE HARD TO PEG AT THIS POINT
AS IT WILL VARY FROM POINT-TO- POINT...BUT GENERALLY 1/4 TO 1/2
INCH SHOULD PREVAIL WEST OF THE MOUNTAINS...WITH LOCAL RAINFALL OF
ONE INCH OR MORE IN THE MOUNTAINS. SNOW LEVELS WILL BE MOSTLY
6000-7000 FEET...SO SEVERAL INCHES COULD FALL IN THE HIGHER
MOUNTAINS...MAINLY SBD COUNTY.

HIGH PRESSURE ALOFT SHOULD BRING FAIR WEATHER EARLY NEXT WEEK WITH
TEMPS RECOVERING TO NEAR NORMAL BY AROUND TUESDAY.

&&

.AVIATION...
040400Z...COASTS/VALLEYS...STRATUS WITH BASES 800-1500 FT MSL WILL
CONTINUE TO FILL IN ALONG THE COAST THIS EVENING...SPREADING 20-25
MI INLAND THROUGH SUNRISE. LOCAL VIS OF 3-5SM IN BR/HZ POSSIBLE
WHERE STRATUS NEARS HIGHER TERRAIN IN THE VALLEYS. STRATUS WILL
SLOWLY CLEAR INLAND 16-18Z...WITH COASTAL AREAS REMAINING SCT-BKN
AND BASES LIFTING TO AROUND 2000-2500 FT MSL THROUGH THE AFTERNOON.
STRATUS WILL BEGIN TO MOVE BACK INLAND AFTER 05/03Z.

MOUNTAINS/DESERTS....SCT CLOUDS AOA 20000 FT MSL AND UNRESTRICTED
VIS THROUGH WEDNESDAY EVENING.

&&

.MARINE...
915 PM...A STORM SYSTEM WILL BRING A SLIGHT CHANCE OF THUNDERSTORMS
THURSDAY AFTERNOON THROUGH FRIDAY NIGHT. THESE STORMS COULD PRODUCE
CLOUD TO WATER LIGHTNING AND BRIEF GUSTY WINDS. OTHERWISE...NO
HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH SATURDAY.

&&

.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...GREGORIA/MAXWELL
AVIATION/MARINE...SS


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