Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 050342
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
842 PM PDT WED MAY 4 2016

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL SLOWLY APPROACH FROM THE PACIFIC AND
RESULT IN COOLER WEATHER THURSDAY WITH SOME DRIZZLE OR LIGHT SHOWERS
POSSIBLE. MODERATELY STRONG WINDS WILL DEVELOP IN PARTS OF THE
MOUNTAINS AND DESERTS THURSDAY AND THURSDAY NIGHT. SHOWERS WILL
OCCUR AT TIMES THURSDAY NIGHT THROUGH SUNDAY...WITH GREATEST CHANCES
FRIDAY WHEN A FEW THUNDERSTORMS ARE POSSIBLE. TEMPERATURES WILL BE
BELOW NORMAL THURSDAY THROUGH SUNDAY. FAIR AND WARM WEATHER WILL
RETURN NEXT WEEK AS HIGH PRESSURE MOVES OVER THE WEST COAST.

&&

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

LOW CLOUD DECK HAS SPREAD INTO THE INLAND VALLEYS THIS EVENING.
THE SKY WILL BE MOSTLY CLOUDY TO OVERCAST WEST OF THE MOUNTAINS
WITH THE POTENTIAL FOR PATCHY DRIZZLE OVERNIGHT. HIGH RESOLUTION
MODELS SEEM BULLISH WITH SOME SHOWERS DEVELOPING AND MOVING INLAND
OVERNIGHT. BOTH THE GFS AND ECMWF KEEP IT DRY...AND SINCE AM NOT
SEEING ANY INDICATION FOR SHOWERS WILL CONTINUE TO KEEP MENTION
OUT OF THE FORECAST THROUGH THE NIGHT.

THE UPPER LOW IS SOME 550 MI TO OUR WEST/NORTHWEST. THE MODELS
CONTINUE TO BE CONSISTENT WITH THE LOW...MOVING OVER FAR SOUTHERN
CALIFORNIA LATE FRIDAY. RIGHT NOW...THE MARINE LAYER LOOKS
MARGINALLY DEEP FOR PRECIP THU MORNING...SO MOST LIKELY DRIZZLE
WILL OCCUR FROM THE COASTAL MOUNTAIN SLOPES WEST TO THE COAST. THE
ONSHORE FLOW AND FURTHER DEEPENING OF THE MOIST LAYER WILL RESULT
IN SOME RAIN THURSDAY NIGHT/FRIDAY MORNING...WITH A TRANSITION
TOWARDS CONVECTIVE SHOWERS/ISOLATED THUNDERSTORMS DURING THE DAY
FRIDAY AS THE COLD CORE MOVES OVER...WITH -22 C AT 500 MB. BEST
CHANCES WILL BE OVER THE MOUNTAINS DUE TO THE HIGH SUN
ANGLE...THOUGH DYNAMICS COULD COMBINE WITH SOME INSTABILITY ALOFT
TO BRING A FEW TSTORMS FRI MORNING. THERE IS A RISK OF HAIL
FRIDAY...MOSTLY 1/2 INCH OR LESS...BUT UPPER LOWS IN MAY IN
SOUTHERN CALIFORNIA CAN PRODUCE LARGE HAIL. NEAR SATURATION OCCURS
UP TO AROUND 600 MB FRIDAY...WHICH IS GOOD FOR PRECIP. THE LOW
WILL MOVE TO THE NORTHEAST SAT/SUN...BUT ENOUGH MOISTURE AND SOME
INSTABILITY WILL KEEP THE CHANCE OF SHOWERS SAT...AND A SLIGHT
CHANCE SUNDAY. AFTER FRIDAY...MOST OF THE ACTIVITY WILL BE
INLAND...CLOSER TO THE LOW...AND WITH BETTER INSTABILITY AIDED BY
THAT SUN ANGLE. OVERALL...PRECIP AMOUNTS SHOULD BE 1/4 TO 1/2
INCH...WITH LOCAL AMOUNTS OVER 1 INCH IN THE MOUNTAINS FROM
THURSDAY NIGHT THROUGH SUNDAY. SOME WIND WILL OCCUR THU/THU NIGHT
IN THE MOUNTAINS/DESERTS...WITH ISOLATED GUSTS TO NEAR 60 MPH ON
THE DESERT SLOPES...WHEN SOME TEMPERATURE GRADIENTS WILL STILL BE
IN PLACE...BUT AFTER THAT...WINDS WILL BE SOMEWHAT LIGHTER AS THE
CLOSED LOW WILL RESULT IN WEAKER GRADIENTS. A WIND ADVISORY WILL
BE ISSUED FOR SOME MOUNTAIN/DESERT LOCATIONS 3 PM FRIDAY-5 AM
SATURDAY. SNOW LEVELS WILL MOSTLY BE AROUND 7000 FEET...WITH
SEVERAL INCHES OF SNOW POSSIBLE AT HIGHEST ELEVATIONS.

HIGH PRESSURE ALOFT WILL BRING FAIR AND WARMER WEATHER EXCEPT FOR
SOME NIGHT/MORNING COASTAL STRATUS EARLY NEXT WEEK.

&&

.AVIATION...
050330Z...COASTS/VALLEYS...BKN/OVC LOW CLOUDS WITH BASES 2000-2500
FT MSL AND TOPS TO 3000 FT MSL WILL INCREASE IN COVERAGE
OVERNIGHT...OBSCURING HIGHER TERRAIN ON THE COASTAL SLOPES. VIS WILL
DROP TO 3-5 SM WHERE THESE CLOUDS INTERSECT TERRAIN. LIGHT DRIZZLE
WILL ALSO BE POSSIBLE LATE TONIGHT FROM THE COAST TO THE MOUNTAINS.
EXPECT PARTIAL CLEARING TO THE COAST AFTER 17Z THU.

MOUNTAINS/DESERTS...ABOVE THE MARINE LAYER...SCT CLOUDS AOA 15000
FEET WITH UNRESTRICTED VISIBILITY THROUGH THU. GUSTY SW TO WEST
WINDS WILL CONTINUE TO BRING WEAK TO MODERATE UP/DOWNDRAFTS OVER
AND EAST OF THE MOUNTAINS THROUGH THU.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...WIND ADVISORY FROM 3 PM THURSDAY TO 5 AM PDT FRIDAY FOR
     RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO COUNTY DESERTS-SAN
     DIEGO COUNTY MOUNTAINS-SAN GORGONIO PASS NEAR BANNING.
PZ...NONE.

&&

$$

PUBLIC...GREGORIA/MAXWELL
AVIATION/MARINE...PG


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