Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 290503
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1003 PM PDT THU APR 28 2016

.SYNOPSIS...
TONIGHT...LOW CLOUDS AND FOG WILL CONTINUE TO PUSH UP AGAINST THE
COASTAL SLOPES. BY TOMORROW...WEAK RIDGING ALOFT WILL DEVELOP OVER
SOUTHERN CALIFORNIA AND BRING FAIR CONDITIONS TO THE REGION.
SLIGHTLY WARMER WEATHER IS EXPECTED NEAR THE COAST WITH 5 TO 10
DEGREES OF WARMING INLAND. A LOW PRESSURE SYSTEM WILL DROP
SOUTHWARD OVER THE REGION ON FRIDAY NIGHT WHICH WILL CREATE GUSTY
WINDS IN THE MOUNTAINS AND DESERTS...LOWER TEMPERATURES...AND
BRING A SLIGHT CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS TO
INLAND AREAS. HIGH PRESSURE WILL BUILD OVER THE WEST COAST EARLY
NEXT WEEK AND BRING A RETURN TO THE WARMER AND DRYER WEATHER.

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

AT 9 PM PDT...IR SATELLITE IMAGERY SHOWED A DEEP CLOSED LOW
SPINNING CYCLONICALLY NEAR THE FOUR CORNERS REGION. SCATTERED MID
AND UPPER-LEVEL CLOUDS COULD BE SEEN SLIDING PAST THE CA/AZ
BORDER. THE 29/0000Z KNKX RAOB INDICATED A RELATIVELY MOIST LAYER
BELOW 700 MB WITH DRY AIR ALOFT AND WESTERLY WINDS UPWARDS FROM
THE SURFACE TO 300 MB. RAIN SHOWERS HAVE DWINDLED OVER SOUTHWEST
CA THIS EVENING. PRECIPITATION TOTALS FROM THIS LAST STORM SYSTEM
WERE RATHER UNIMPRESSIVE WITH A FEW HUNDREDTHS OF AN INCH
ACCUMULATING ALONG THE COAST AND IN THE COASTAL BASINS. HIGHEST
AMOUNTS...TO AROUND HALF AN INCH...WERE REPORTED IN THE NORTHERN
MOUNTAINS.

ON FRIDAY...A WEAK TRANSIENT RIDGE WILL MOVE ACROSS SOUTHERN
CALIFORNIA. THIS FEATURE WILL ACT TO INCREASE TEMPERATURES SLIGHTLY
ALONG THE COAST AND UP TO 5 TO 10 DEGREES HIGHER INLAND. FRIDAY
NIGHT...500 MB PRESSURE HEIGHTS WILL LOWER AS A COMPACT VORT MAX
SLIDES SOUTHWARD FROM WESTERN NEVADA AND APPROACHES SOUTHERN
CALIFORNIA. AS SURFACE PRESSURE GRADIENTS TIGHTEN...WESTERLY WINDS
WILL BECOME GUSTY OVER THE MOUNTAIN RIDGE TOPS AND DESERT SLOPES.
WINDS COULD GUST BETWEEN 35 AND 50 MPH IN THE MORE WIND PRONE
LOCATIONS. ON SATURDAY...COOLER WEATHER IS EXPECTED WITH MAXIMUM
TEMPERATURES RANGING BETWEEN 5 AND 15 DEGREES BELOW NORMAL FOR
THIS TIME OF YEAR. AS THE VORT MAX INTERACTS WITH LIMITED
MOISTURE...THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND ISOLATED
THUNDERSTORMS OVER PORTIONS OF THE MOUNTAINS AND UPPER
DESERTS...WHERE INSTABILITY IS THE GREATEST. HOWEVER...RAINFALL
WILL BE VARIABLE AND ONLY LIGHT AMOUNTS ARE EXPECTED TO
ACCUMULATE. THE SNOW LEVEL WILL BE HIGH...ABOVE 8000 FEET...SO
ONLY THE TALLEST PEAKS OF THE SAN BERNARDINOS WILL EXPERIENCE
FLURRIES. THE LOW PRESSURE TROUGH SLOWLY MOVES OUT ON SUNDAY WITH
DECREASING WINDS AND DRYING.

MONDAY INTO WEDNESDAY OF NEXT WEEK...BOTH THE 00Z GFS AND 12Z ECMWF
DEVELOP A PRONOUNCED RIDGE OF HIGH PRESSURE OVER THE WEST COAST.
THIS FEATURE WILL BRING WARMER AND DRYER WEATHER TO SOUTHERN
CALIFORNIA ARE RISE TEMPERATURES SLIGHTLY ABOVE NORMAL. THE LONG
RANGE MODELS HAVE BEEN CONSISTENTLY PUSHING A DEEP LOW PRESSURE
TROUGH TOWARDS SOUTHERN CALIFORNIA DURING THE THURSDAY/FRIDAY TIME
FRAME. THIS STORM APPEARS TO GRAB MORE MOISTURE THAN THE LAST
FEW...DUE TO ITS OVER WATER TRAJECTORY...AND GENERATES ADDITIONAL
PRECIPITATION OVER SOUTHERN CALIFORNIA.

&&

.AVIATION...
290430Z...COAST/VALLEYS...AREAS OF LOW CLOUDS WILL CONTINUE
OVERNIGHT WITH BASES MOSTLY 1800-3000 FT MSL WITH VARIABLE TOPS
5000-7000 FT MSL. CLOUDS WILL BE MOST NUMEROUS IN THE VALLEYS AND
LEAST PREVALENT IN ORANGE COUNTY. CLEARING WILL BE SLOW
FRIDAY...MOSTLY 18Z-20Z...WITH THE VALLEYS CLEARING LAST. MOST
VIS WILL BE 6+ MILES...THOUGH SOME OF THE HIGHER TERRAIN WILL BE
OBSCURED AT TIMES.

MOUNTAINS/DESERTS...AREAS OF TERRAIN OBSCURATIONS WILL OCCUR IN THE
MOUNTAINS THROUGH 20Z FRI...BUT ONLY SCT CLOUDS MOSTLY AT/ABOVE 8000
FEET MSL WILL OCCUR IN THE DESERTS. LOCAL WINDS 20-30 KT GUSTS TO 45
KNOTS WILL OCCUR ON DESERT MOUNTAIN SLOPES TONIGHT...WEAKENING FRI.

&&

.MARINE...
930 PM...CONDITIONS WILL IMPROVE OVER THE COASTAL WATERS TONIGHT AS
THE SMALL CRAFT ADVISORY HAS EXPIRED. SEAS WILL BE 8 FEET OR LESS
WITH WINDS 20 KNOTS OR LESS.

&&

.BEACHES...
930 PM...HIGH RIP CURRENT RISK WILL CONTINUE THROUGH AT LEAST
SATURDAY WITH 3-5 FOOT SURF WITH LOCAL SETS TO 6 FEET AT TIMES.

&&

.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...JT
AVIATION/MARINE...MAXWELL


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