Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 222005
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
104 PM PDT MON SEP 22 2014

.SYNOPSIS...
A BUILDING RIDGE OF HIGH PRESSURE ALOFT WILL BRING WARMER WEATHER
THROUGH MIDWEEK AS INLAND TEMPERATURES RISE TO 5-10 DEGREES ABOVE
AVERAGE. THE INLAND EXTENT OF NIGHT AND MORNING LOW CLOUDS WILL ALSO
SHRINK...BECOMING CONFINED TO THE IMMEDIATE COAST BY WEDNESDAY
MORNING. A DEEPENING TROUGH OF LOW PRESSURE ALONG THE WEST COAST BY
FRIDAY WILL BRING BREEZY AND COOLER WEATHER...WITH A DEEPENING
MARINE LAYER INTO THE WEEKEND ACCOMPANIED BY GUSTY WINDS IN THE
MOUNTAINS AND DESERTS.

&&

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

AUTUMN BEGINS TONIGHT AT 729 PM PDT.

THE MARINE STRATUS WAS DRAMATICALLY REDUCED THIS MORNING AS THE
MARINE INVERSION WAS CUT IN HALF FROM YESTERDAY. PATCHY STRATUS
CONTINUED OFF THE COAST AT MIDDAY...AND MAY IMPACT SOME BEACHES
LOCALLY THIS AFTERNOON...OTHERWISE IT WILL BE CLEAR UNTIL LATER THIS
EVENING WHEN THE MARINE CLOUDS ARE EXPECTED TO REDEVELOP. ONSHORE
SURFACE PRESSURE GRADIENTS WERE SLIGHTLY WEAKER THAN YESTERDAY SO
WINDS SHOULD NOT BE A PROBLEM THROUGH AND BELOW THE PASSES THIS
EVENING.

THE WEATHER WILL BE DRY AND WARMER THROUGH WED AS HIGH PRESSURE
BUILDS ALOFT. 12Z MODELS AGREE THE HIGH WILL PEAK OVER THE REGION AT
592 DM BEFORE SLIDING OFF TO THE NE WED/THU. HOWEVER...HEIGHTS AND
THICKNESS WILL REMAIN ELEVATED OVER THE REGION INTO EARLY FRI AS A
TROUGH DIGS SOUTH ALONG 130W. THIS WILL KEEP THE MARINE LAYER RATHER
SHALLOW WITH LIMITED MARINE CLOUDS...BUT POSSIBLY MORE FOG AS
MOISTURE BECOMES CONCENTRATED IN THE BOUNDARY LAYER AND THE LONGER
NIGHTS ALLOW MORE COOLING. A SEA BREEZE WILL DEVELOP EACH DAY AND
BECOME QUITE GUSTY LATER IN THE WEEK AS SFC PRESSURE FALLS OVER THE
GREAT BASIN. DAYTIME HIGHS WILL GRADUALLY LOWER AGAIN THU THROUGH
SAT IN RESPONSE TO THE INCOMING TROUGH AND ONSHORE FLOW.

THERE REMAIN CONSIDERABLE DIFFERENCES IN THE LATEST MODEL SOLUTIONS
REGARDING THE TROUGH LATER IN THE WEEK. THE GFS MODEL IS THE MOST
PROGRESSIVE...WHILE THE ECMWF CUTS OFF THE SYSTEM AND HOLDS IT BACK
OVER CA THROUGH SUN MORNING. THE 00Z MON GEM SEEMS TO SPLIT THE
DIFFERENCE. NO MODEL GENERATES PRECIP ACROSS SOCAL...SO THE BEST WE
CAN HOPE FOR AT THIS TIME IS A DIFFERENT OUTCOME...OR PERHAPS SOME
MARINE LAYER DRIZZLE ONE MORNING.

OTHER THAN THE COOLING...THE MAIN WEATHER ELEMENT FROM THE TROUGH
WILL BE GUSTY ONSHORE WINDS. ADVISORY STRENGTH LOOKS POSSIBLE AT
SOME POINT FRI OR SAT OVER THE MTNS/DESERTS. BEHIND THE TROUGH IT
WILL BE WARMER EARLY NEXT WEEK WITH TEMPERATURES ABOUT AVERAGE FOR
LATE SEP/EARLY OCT.

NOTE...SEA SURFACE TEMPERATURES OVER THE BIGHT ARE RUNNING 3-5
DEGREES F ABOVE AVERAGE. UNTIL UPWELLING BRINGS COOLER WATER TO THE
SURFACE IT WILL BE DIFFICULT TO GET OVERNIGHT LOW TEMPERATURES
ANYWHERE ALONG OUR COAST CLOSE TO AVERAGE WITHOUT A GOOD OFFSHORE
DRIFT AND CLEAR SKY. DAYTIME HIGHS ARE LIKELY TO BE INFLUENCED AS
WELL. SO FAR IN SEPTEMBER...THE AVERAGE TEMPERATURE AT LINDBERGH
FIELD IS RUNNING 5.7 DEGREES F ABOVE NORMAL. MANY OTHER SITES ACROSS
THE SOUTHLAND ARE 4-5 DEGREES F ABOVE NORMAL AS WELL.

&&

.AVIATION...
222030Z...CLEAR THIS AFTERNOON...EXCEPT FOR A FEW PATCHES OF LOW
CLOUDS OVER THE COASTAL WATERS. LOW CLOUDS WILL RETURN TO COASTAL
TAF SITES AFT 06Z TUE WITH BASES AROUND 1000 FT MSL AND TOPS AROUND
1500 FT MSL. LOW CLOUDS WILL SPREAD A FEW MILES INLAND OVERNIGHT
WITH AREAS OF VIS 3-5SM AND LOCALLY BLO 3SM WHERE CLOUDS AND TERRAIN
INTERSECT. LOW CLOUDS WILL CLEAR TO THE COAST BETWEEN 15Z AND 17Z
TUE. OTHERWISE...MOSTLY CLEAR WITH UNRESTRICTED VIS THROUGH TUE.

&&

.MARINE...
200 PM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH FRIDAY.

&&

.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...JAD
AVIATION/MARINE...PG











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