Area Forecast Discussion
Issued by NWS San Diego, CA

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000 FXUS66 KSGX 301636 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 936 AM PDT SAT AUG 30 2014 .SYNOPSIS... STRONG RIP AND LONGSHORE CURRENTS WILL BE POSSIBLE ALONG THE BEACHES THROUGH THE HOLIDAY WEEKEND. A COASTAL EDDY AND INCREASING ONSHORE FLOW WILL CONTINUE THE COOLING TREND FROM THE COAST TO INLAND AREAS THROUGH NEXT WEEK. THE MARINE LAYER WILL DEEPEN...WITH NIGHT AND MORNING LOW CLOUDS AND FOG DEVELOPING INTO THE INLAND VALLEYS. DRY WEATHER IS FORECAST THROUGH NEXT WEEKEND. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... AT 9 AM PDT...WATER VAPOR SATELLITE IMAGERY DISPLAYED AN UPPER- LEVEL RIDGE CENTERED JUST OFFSHORE OF SOUTHWEST CALIFORNIA...AND A WEAK SHORTWAVE TROUGH MOVING SOUTHEAST ACROSS CENTRAL CALIFORNIA AND CENTRAL NEVADA. VISIBLE SATELLITE SHOWED MARINE LAYER STRATUS SLOWLY CLEARING TOWARDS THE COAST IN COASTAL AND VALLEY AREAS. THE 30/1200 UTC KNKX SOUNDING DISPLAYED DRY WEST FLOW ALONG THE COLUMN...A CALCULATED 0.83 INCHES OF PRECIPITABLE WATER...AND AN 8 DEGREE C MARINE LAYER INVERSION. TEMPERATURES WERE A FEW DEGREES COOLER COMPARED TO THIS TIME YESTERDAY. THE 8 DEGREE C MARINE LAYER INVERSION SHOULD NOT BE STRONG ENOUGH TO INHIBIT CLEARING ALONG THE COAST TODAY. HOWEVER...A FEW COASTAL LOCATIONS MAY SEE SCATTERED TO BROKEN LOW CLOUDS AT TIMES THROUGHOUT THE DAY. LOWERING HEIGHTS ALOFT WILL HELP INLAND AREAS TO SLOWLY COOL THROUGHOUT THE HOLIDAY WEEKEND...WHILE A COASTAL EDDY WILL HELP DEEPEN THE MARINE LAYER AND CONTINUE THE COOLING TREND OVER THE COAST AND VALLEYS. A SHORTWAVE TROUGH MOVING SOUTHEAST ACROSS THE GREAT BASIN TODAY WILL CREATE BREEZY WESTERLY WINDS TO 40 MPH ACROSS PORTIONS OF THE HIGH DESERT THIS AFTERNOON AND EVENING. WESTERLY FLOW ALOFT WILL CONTINUE THROUGH EARLY NEXT WEEK AS THE UPPER-LEVEL RIDGE FLATTENS AND TRAVERSES TO THE SOUTHWEST. A BROAD UPPER-LEVEL RIDGE WILL THEN DEVELOP OVER THE SOUTHERN PORTION OF THE CONTIGUOUS UNITED STATES...SHIFTING THE FLOW TO MORE SOUTHWESTERLY. BY THE END OF NEXT WEEK...THE UPPER-LEVEL RIDGE WILL PUSH EASTWARD AS AN UPPER-LEVEL TROUGH DIGS ALONG THE WEST COAST. THIS WILL HELP TO LOWER HEIGHTS ALOFT AND ALLOW THE MARINE LAYER TO DEEPEN...WITH NIGHT AND MORNING LOW CLOUDS/FOG REACHING THE FAR INLAND VALLEYS EACH MORNING. DRY WEATHER...WITH SLIGHTLY BELOW NORMAL HIGH TEMPERATURES WILL LIKELY DEVELOP MOST THE NEXT WORK WEEK. THE FORECAST CHALLENGE REMAINS FOR NEXT WEEKEND AS THE 30/0600 UTC GFS CONTINUES THE TROUGH AND DRY SOUTHWEST FLOW ALONG THE WEST COAST...WHILE THE 30/0000 UTC MOVES THE RIDGE OVER THE FOUR CORNERS AND HINTS AT MOIST...SOUTHEASTERLY FLOW WITH MONSOONAL MOISTURE KNOCKING ON OUR DOOR BY THE END OF NEXT WEEKEND. && .AVIATION... 301608Z...COAST/VALLEYS...STRATUS 15-20 MILES INLAND WITH BASES 900-1100 FT ABOVE MEAN SEA LEVEL...TOPS 1300-1600 FT ABOVE MEAN SEA LEVEL...AND AREAS OF 3-5 SM VISIBILITY...WILL CLEAR TO THE COASTAL WATERS THROUGH 1900 UTC. 1900-31/0000 UTC...MOSTLY CLEAR SKIES AND UNRESTRICTED VISIBILITY...EXCEPT THERES A CHANCE OF SCATTERED-TO-BROKEN STRATUS 1200-1500 FT ABOVE MEAN SEA LEVEL WITHIN 5 MILES OF THE COAST. 31/0000-0900 UTC...STRATUS DEVELOPING FROM SOUTH TO NORTH WITHIN 10-20 MILES OF THE COAST...WITH BASES 1200-1700 FT ABOVE MEAN SEA LEVEL AND TOPS 1700-2300 FT ABOVE MEAN SEA LEVEL. THESE CONDITIONS CONTINUING THROUGH 31/1400 UTC. CONFIDENCE IN TIMING OF STRATUS ARRIVAL TO KSAN...KCRQ AND KSNA IS LOW-TO-MODERATE...WITH HIGH CONFIDENCE IN STRATUS OCCURRENCE AND MODERATE-TO-HIGH CONFIDENCE IN CEILING HEIGHTS. LOCAL VISIBILITY OF 2-5 MILES WILL OCCUR OVER INLAND MESAS. MOUNTAINS/DESERTS...UNRESTRICTED VISIBILITY AND FEW CLOUDS AT OR ABOVE 20000 FT ABOVE MEAN SEA LEVEL THROUGH SUNDAY MORNING. && .MARINE... 908 AM...NO HAZARDOUS MARINE WEATHER EXPECTED THROUGH WEDNESDAY. && .BEACHES... LONG-PERIOD SOUTHWEST SWELL WILL SLOWLY CONTINUE THROUGH MONDAY...PRODUCING STRONG RIP AND LONGSHORE CURRENTS...AND LOCAL 5 FOOT SETS FOR THE HOLIDAY WEEKEND. A BEACH HAZARDS STATEMENT HAS BEEN ISSUED FOR THE ORANGE AND SAN DIEGO COUNTY BEACHES AND CONTINUES THROUGH EARLY MONDAY EVENING. && .SKYWARN... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...BEACH HAZARDS STATEMENT THROUGH MONDAY EVENING FOR THE BEACHES IN THE ORANGE COUNTY COASTAL AREAS...SAN DIEGO COUNTY COASTAL AREAS. PZ...NONE. && $$ PUBLIC...JJT AVIATION/MARINE/BEACHES...HARRISON

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