Area Forecast Discussion
Issued by NWS San Diego, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KSGX 192015
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
115 PM PDT FRI SEP 19 2014

.SYNOPSIS...
A LOW PRESSURE TROUGH MOVING SLOWLY THROUGH CENTRAL TO SOUTHERN
CALIFORNIA WILL CONTINUE TO BRING COOLER WEATHER AND NIGHT AND
MORNING STRATUS INTO THE COAST AND VALLEYS SECTIONS THROUGH SUNDAY.
THE MARINE LAYER MAY ONCE AGAIN PRODUCE PATCHY DRIZZLE TONIGHT
THROUGH TOMORROW MORNING. ISOLATED THUNDERSTORMS MAY FORM OVER THE
MOUNTAINS SATURDAY AFTERNOON DUE TO A POSSIBLE INCREASE IN MOISTURE
FROM THE SOUTH. A WARMING TREND AND SHALLOWER MARINE LAYER IS
EXPECTED FOR NEXT MONDAY THROUGH WEDNESDAY AS HIGH PRESSURE ALOFT
EXPANDS INTO THE REGION. THEN...ANOTHER TROUGH MOVING INLAND ALONG
THE WEST COAST MAY BRING COOLING...A DEEPER MARINE LAYER...AND
INCREASING ONSHORE FLOW.

&&

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

VISIBLE SATELLITE IMAGERY SOME LINGERING SCATTERED CUMULUS CLOUDS
OVER THE COAST...VALLEYS AND SOME CONVECTIVE CUMULUS OVER THE
MOUNTAINS THIS AFTERNOON. THE STRATUS WAS VERY SLOW TO CLEAR
TODAY...HELPING TO BRING TEMPERATURES SEVERAL DEGREES LOWER THAN
THEY WERE 24 HOURS AGO. THE 12Z MIRAMAR SOUNDING SHOWS A WEAK MARINE
LAYER INVERSION AT AROUND 3500 FEET...AND RECENT PILOT REPORTS
INDICATE THAT TOPS HAVE REACHED 4000 FEET. THUS...THE MARINE LAYER
WAS AROUND 4000 FEET DEEP THIS MORNING. WITH WEAKER ONSHORE FLOW
TODAY...THE STRATUS MAY COME IN SLIGHTLY LATER THIS EVENING THAN IT
DID YESTERDAY...BUT IT SHOULD FILL INTO THE FAR INLAND VALLEYS AGAIN
THROUGH EARLY SATURDAY MORNING. HIGH RES MODELS INDICATE SPOTTY VERY
LIGHT ACCUMULATIONS ALONG THE COAST ASSOCIATED WITH THE MARINE
LAYER...WHICH IMPLIES POSSIBLE DRIZZLE OVERNIGHT. SPEAKING OF
WEAKENING ONSHORE FLOW...THE ONSHORE PRESSURE GRADIENTS FROM SAN
DIEGO TO DAGGETT ARE DOWN TO 2.9 MB...WHEREAS THEY WERE 6.0 MB AT
THIS TIME 24 HOURS AGO. THUS...WINDS HAVE WEAKENED IN THE MOUNTAINS
AND DESERTS...WITH MAINLY GUSS IN THE 10S TO 20S.

WATER VAPOR SATELLITE SHOWS A SOUTHWEST TO NORTHEAST ORIENTED TROUGH
CONTINUING TO MOVE SOUTH TOWARDS SOUTHERN CALIFORNIA FROM ITS
CURRENT POSITION OVER CENTRAL CALIFORNIA. AS THE TROUGH CONTINUES TO
MOVE SOUTH...A CLOSED LOW WILL SPLIT OUT OF IT...AND ASSUME A
POSITION JUST OFFSHORE OF POINT CONCEPTION LATE TONIGHT. THE LOW
WILL MOVE INLAND DURING THE DAY SATURDAY...AND THE SOUTH FLOW ON THE
EASTERN EDGE OF THE CIRCULATION MAY DRAW UP ENOUGH MOISTURE TO BRING
AN AFTERNOON THUNDERSTORM OR TWO TO THE MOUNTAINS AND HIGH DESERTS.
HOWEVER...IT IS A PRETTY SLIM CHANCE...AS THE BULK OF THE MOISTURE
REMAINS TO OUR EAST. THE NAM12 IS PARTICULARLY DRY FOR OUR AREA ON
SATURDAY. THE LOW WILL BE INTO NEVADA BY SUNDAY MORNING...AND SOME
SMALL RISE IN 850 MB TEMPERATURES MAY BRING SLIGHT WARMING THAT
DAY...ALTHOUGH DAY-TIME HIGHS WILL STILL MOSTLY BE BELOW NORMAL.
NIGHT AND MORNING STRATUS WILL CONTINUE TO MOVE INTO THE VALLEYS.

A RIDGE TO THE SOUTH IS LIKELY TO EXPAND INTO THE REGION MONDAY
THROUGH WEDNESDAY...RESULTING IN A CONTINUED WARMING TREND...WITH
DAY-TIME HIGH TEMPERATURES REACHING A FEW TO SEVERAL DEGREES ABOVE
NORMAL. THE MARINE LAYER WILL BECOME MUCH SHALLOWER AS WELL...WITH
NIGHT AND MORNING STRATUS/FOG INTO THE COASTAL SECTIONS AND MAYBE
THE WESTERN VALLEYS AT TIMES. GFS SHOWS SOME INCREASE IN
PRECIPITABLE WATER ON WEDNESDAY AS THE LOW-TO-MID LEVEL FLOW CHANGES
TO THE SOUTH-SOUTHWEST OR SOUTH...WHICH MAY RESULT IN SOME AFTERNOON
CUMULUS TO THE MOUNTAINS...BUT RIGHT NOW THUNDERSTORMS DO NOT APPEAR
LIKELY. ALL MODELS THEN SHOW A DEEP TROUGH MOVING IN ALONG THE WEST
COAST THURSDAY INTO FRIDAY WHICH WOULD BRING ANOTHER COOLING
TREND...WITH A DEEPER MARINE LAYER AND GUSTY ONSHORE FLOW. RIGHT
NOW...MODELS DO NOT SHOW US GETTING PRECIPITATION FROM THIS SYSTEM.

&&

.AVIATION...
191934Z...COAST/VALLEYS...SCT CLOUDS AOA 3000 FEET THROUGH 00Z THIS
AFTERNOON. AFT 00Z THROUGH 06Z...THE STRATUS LAYER WILL REFORM OVER
COASTAL AREAS AND SPREAD RAPIDLY INLAND WITH BASES AROUND 2500 FEET
AND TOPS 3000-3500 FEET. BKN-OVC CIGS SHOULD REMAIN WEST OF THE MTNS
THROUGH 16Z AND MIX OUT 17Z-19Z ON SAT MORNING.

MOUNTAINS/DESERTS...FEW CU OVER THE RIDGES THIS AFTERNOON AND SOME
TERRAIN OBSCURATION ON THE LOWER COASTAL SLOPES BELOW 4000 FT 06Z-
18Z SAT. OTHERWISE...SKIES WILL BE CLEAR AND VIS UNRESTRICTED
THROUGH TONIGHT. THERE IS A CHANCE FOR CU AND A SMALL CHANCE FOR
ISOLATED CONVECTION OVER THE MTNS OF RIVERSIDE/SAN BERNARDINO
COUNTIES ON SAT.

&&

.MARINE...
1230 PM...NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH TUESDAY.

&&

.BEACHES...
1230 PM...THROUGH THIS EVENING...LOCAL SURF OF 3 TO 5 FEET ON
SOUTHWEST FACING BEACHES ALONG WITH STRONG RIP CURRENTS. SOUTH-
SOUTHWEST SWELL WILL LOWER THROUGH SATURDAY WITH DIMINISHING RIP
CURRENTS.

&&

.SKYWARN...
SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.

&&

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

&&

$$

PUBLIC...HARRISON
AVIATION/MARINE/BEACHES...JAD





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.