Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 232134
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
200 PM PDT WED APR 23 2014

.SYNOPSIS...
WEAK HIGH PRESSURE ALOFT WILL BRING SEASONAL WEATHER TONIGHT AND
THURSDAY. A STRONG...COLD LOW PRESSURE TROUGH WILL MOVE ACROSS
SOUTHERN CALIFORNIA FRIDAY AND SATURDAY BRINGING COOL...WINDY
WEATHER AS WELL AS SCATTERED SHOWERS ALONG AND WEST OF THE
MOUNTAINS. A STRONG RIDGE OF HIGH PRESSURE BUILDING OVER THE WEST
WILL BRING MUCH WARMER WEATHER NEXT WEEK.

&&

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

TRANQUIL WEATHER TONIGHT AND THURSDAY WITH GENERALLY LIGHT WINDS AND
MOSTLY CLEAR SKIES. ANY LATE NIGHT LOW CLOUDS FROM A SHALLOW MARINE
LAYER WILL BE CONFINED TO THE COASTAL AREAS. MOSTLY SUNNY AND WARM
THURSDAY WITH HIGH TEMPERATURES A LITTLE HIGHER THAN AVERAGE FOR
LATE APRIL. THAT ALL CHANGES FRIDAY AND SATURDAY WITH A COLD PACIFIC
TROUGH IMPACTS THE WEST COAST.

THE EC...GFS AND CANADIAN MODELS ARE ALL IN GOOD AGREEMENT WITH THE
TRACK...TIMING AND INTENSITY OF THIS STRONG SPRING STORM. FRIDAY
WILL TURN COOLER AND PROGRESSIVELY WINDIER AS THE THROUGH MOVES DOWN
THE WEST COAST. BY FRIDAY AFTERNOON A 546 DM UPPER LOW WILL BE NEAR
SFO WITH A 997 MB SFC LOW OVER THE GREAT BASIN. THE MARINE LAYER
WILL DEEPEN RAPIDLY THROUGH FRIDAY TO AROUND 5000 FEET BY EVENING.

A STRONG VORT MAX ROTATES AROUND THE BASE OF THE TROUGH AND DIRECTLY
OVER SOCAL FRIDAY NIGHT THROUGH SATURDAY MORNING. PRECIPITABLE WATER
INCREASES TO AROUND 0.90" FRIDAY EVENING WITH DYNAMIC FORCING LIKELY
TO GENERATE SCATTERED SHOWERS JUST ABOUT ANYWHERE ALONG AND WEST OF
THE MOUNTAINS. BEST CHANCES WILL BE ON THE COASTAL MOUNTAIN SLOPES
WHERE STRONG 40-45 KT 850 MB FLOW NEARLY PERPENDICULAR TO THE SAN
JACINTO AND SAN DIEGO COUNTY MOUNTAIN RANGES WILL ENHANCE OROGRAPHIC
PRECIPITATION. RAIN AMOUNTS WILL BE VARIABLE WITH THIS
SYSTEM...RANGING FROM A FEW HUNDREDTHS TO A QUARTER INCH WEST OF THE
MOUNTAINS...A QUARTER TO HALF INCH IN THE MOUNTAINS...AND ISOLATED
AMOUNTS OF 0.75" ON FAVORED SLOPES. SNOW LEVELS LOWER TO 4000-5000
FEET FRIDAY NIGHT/SATURDAY MORNING WITH 1-3 INCHES OF SNOW
ACCUMULATION ABOVE 5000 FEET IN AREAS THAT GET THE HEAVIEST SNOW
SHOWERS.

THE STRONG WINDS ALOFT COMBINED WITH DOUBLE DIGIT ONSHORE SURFACE
PRESSURE GRADIENTS WILL GENERATE STRONG WINDS FRIDAY EVENING THROUGH
SATURDAY MORNING. WIND ADVISORIES OR HIGH WIND WARNINGS WILL BE
NEEDED. BLOWING DUST AND SAND WILL RESTRICT VISIBILITIES IN THE
DESERTS. GALE FORCE WINDS ARE POSSIBLE OVER THE OUTER WATERS.

THE TROUGH MOVES EAST SATURDAY EVENING AND THE WINDS WILL GRADUALLY
DECREASE. A HIGH PRESSURE RIDGE BEGINS TO BUILD OVER THE WEST
ON SUNDAY AND WILL CONTINUE TO AMPLIFY ALONG THE WEST COAST THROUGH
TUESDAY. TEMPERATURES WILL BE TRENDING STEADILY UPWARD EACH DAY WITH
VALLEYS HIGHS IN THE 90S BY TUESDAY...AND COASTAL HIGHS IN THE 80S.

&&

.AVIATION...
232000Z...COAST/VALLEYS...MOSTLY CLEAR SKIES WITH SCT CIRRUS THROUGH
THIS EVENING. SCT LOW CLOUDS MAY RETURN TONIGHT TO THE COASTAL
AREAS...THOUGH CIGS APPEAR UNLIKELY AT THIS TIME. ANY CIGS THAT DO
FORM OVER THE COASTAL AIRPORTS WILL BE BRIEF AND JUST BEFORE
SUNRISE. ANY LOW CLOUDS WILL DISSIPATE BY MID SATURDAY
MORNING...LEAVING MOSTLY CLEAR SKIES AND UNRESTRICTED VIS.

MTNS/DESERTS...MOSTLY CLEAR WITH UNRESTRICTED VIS THROUGH WED
EVENING.

&&

.MARINE...
THE 1 PM PDT SAN CLEMENTE ISLAND BASIN BUOY OBS SHOW COMBINED SEAS
SLOWLY BUT SURELY LOWERING TO AROUND 8 FEET. EXPECT SEAS TO CONTINUE
SUBSIDING THROUGH THE END OF THE WEEK.

FRI AFTERNOON THROUGH SAT...20-30 KT WINDS ARE LIKELY TO DEVELOP
OVER THE COASTAL WATERS...ACCOMPANIED BY A STEEP WNW SWELL.
CONFIDENCE IS HIGH THIS WILL GENERATE CONDITIONS HAZARDOUS FOR SMALL
CRAFT DURING THIS PERIOD.

A 4 FT LONG-PERIOD SOUTH SWELL THIS WEEKEND MAY PRODUCE HIGH SURF
CONDITIONS WITH SETS OF 7 TO 8 FT ALONG FAVORED SOUTH-FACING BEACHES
OF ORANGE COUNTY. STRONG LONGSHORE AND RIP CURRENTS ARE LIKELY AT
MANY BEACHES OF SAN DIEGO AND ORANGE COUNTY AS WELL.

&&

.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.

&&

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

&&

$$

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








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