FXUS66 KSGX 060514 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 912 PM PST WED JAN 5 2011 .SYNOPSIS...FAIR INTO THURSDAY WITH HIGH CLOUDINESS UNDER WEAK HIGH PRESSURE. A WEAK UPPER LOW OFF THE COAST WILL MOVE INLAND ACROSS SOUTHERN CALIFORNIA...BRINGING A SMALL CHANCE OF LIGHT SHOWERS LATE THURSDAY INTO FRIDAY. ONSHORE FLOW WILL BRING SOME MARINE LAYER CLOUDS WEST OF THE MOUNTAINS OVER THE WEEKEND...OTHERWISE DRY IN NORTHWEST FLOW ALOFT INTO EARLY NEXT WEEK. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. SKIES WERE MOSTLY CLEAR THIS EVENING ASIDE FROM SCATTERED CIRRUS CLOUDS. IT COOLED OFF QUICKLY AFTER SUNSET DUE TO THE DRY AIR AND MOSTLY LIGHT WINDS...EXCEPT IN SOME OF THE WINDER SPOTS IN THE FOOTHILLS WHERE STRONG OFFSHORE SURFACE PRESSURE GRADIENTS WERE SUPPORTING WIND GUSTS IN THE 15 TO 25 MPH RANGE. WEAKENING HIGH PRESSURE ALOFT AND WEAKENING OFFSHORE FLOW THROUGH THURSDAY SHOULD BRING ANOTHER FAIR AND MILD DAY ON THURSDAY. THE OFFSHORE FLOW WILL CAUSE LOCAL GUSTY WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES AGAIN DURING THE DAY...BUT THEY SHOULD MOSTLY REMAIN BELOW ADVISORY STRENGTH. SATELLITE IMAGERY AT 04Z SHOWED A CUT-OFF STORM CENTER ABOUT 600 NM WSW OF SAN DIEGO WITH BANDS OF ENHANCED CONVECTION CIRCULATING AROUND IT. POES DERIVED TPW IMAGERY SHOWED VALUES OF AROUND ONE INCH HAD WRAPPED COMPLETELY AROUND THE SYSTEM...HELPING TO SUPPORT THE CONVECTION. A DEEPER AREA OF SUBTROPICAL MOISTURE WAS EVIDENT WELL SOUTH OF THE STORM CENTER...SOUTH OF 20N AND WAS SHOWING NO SIGN OF ADVANCING NORTHWARD. THE LOW CENTER SHOULD BEGIN MOVING EAST LATER TONIGHT AND IS EXPECTED TO ARRIVE AT THE COAST FRI MORNING. THE MODELS HAVE ALL KEPT THE SYSTEM INTACT WITH A DECENT JET AROUND THE SOUTH SIDE...BUT DEVELOP LITTLE...IF ANY PRECIPITATION OVER SOCAL AS IT MOVES THROUGH FRI. EXPECT THERE WILL BE A CHANCE FOR A FEW SHOWERS...BUT THEY WILL HAVE TO OVERCOME A DEEP DRY LAYER AND SHOULD BE SCATTERED. THIS SYSTEM WILL BE MONITORED CLOSELY...BUT BASED ON CONSISTENT MODEL GUIDANCE...PARAMETERS TO SUPPORT A SIGNIFICANT RAIN EVENT JUST ARE NOT THERE. IT SHOULD BE SLIGHTLY COOLER FRI UNDER THE LOW. RESIDUAL LOW LEVEL MOISTURE MAY CAUSE AREAS OF COASTAL LOW CLOUDS AND FOG FRI NIGHT AND SAT MORNING. EXCEPT FOR THE MARINE LAYER CLOUDS...SKIES WILL BE MOSTLY CLEAR IN DRY NRLY FLOW ALOFT. CONTINUED COOL SATURDAY. A WEAK SHORT WAVE WILL MOVE THROUGH SATURDAY NIGHT THAT WILL PROBABLY NOT CAUSE ANY PRECIP BUT SHOULD BRIEFLY DEEPEN THE MARINE LAYER FOR MORE CLOUDS WEST OF THE MOUNTAINS. GENERALLY DRY NW FLOW ALOFT WILL CONTINUE EARLY NEXT WEEK WITH DECREASING LOW LEVEL MOISTURE. THIS WILL RESULT IN LESS MARINE LAYER CLOUDINESS AND GRADUAL WARMING. && .AVIATION... 060330Z...VARIABLE MID AND HIGH CLOUDS AOA FL150 AND UNRESTRICTED VIS THROUGH THURSDAY EVENING. LOCAL GUSTY OFFSHORE WINDS WITH GUSTS TO 30 KT WILL CONTINUE THROUGH AND BELOW THE PASSES AND CANYONS WITH ASSOCIATED UDDFS AND LLWS THROUGH 18-20Z. && .SGX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...JAD AVIATION/MARINE...SS  FXUS66 KSGX 010554 AFDSGX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 930 PM PST WED FEB 29 2012 .SYNOPSIS... COOL WITH INCREASING LOW CLOUDS TONIGHT. LIGHT SHOWERS ARE POSSIBLE WEST OF THE MOUNTAINS TONIGHT AND THURSDAY MORNING. VERY STRONG WEST WINDS WILL DEVELOP IN THE MOUNTAINS AND DESERTS THURSDAY MORNING. THE WINDS WILL SHIFT TO THE NORTHEAST...BECOMING OFFSHORE FRIDAY MORNING WITH STRONG GUSTS IN AND BELOW CANYONS AND PASSES. DRY AND WARMER FRIDAY THROUGH THE WEEKEND UNDER CLEAR SKIES. EARLY NEXT WEEK...ONSHORE FLOW WILL RETURN AND BRING COOLING AND MARINE LAYER CLOUDS BACK TO THE COASTAL AREAS. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... THE AFTERNOON SOUNDING FROM NKX SHOWS SOME MOISTURE REMAINING IN THE BOUNDARY LAYER WITH A WEAK INVERSION AT ABOUT 4000 FEET AND STRONG WESTERLY WINDS ABOVE. THE SFC PRESSURE GRADIENTS ARE TRENDING STRONGER ONSHORE WITH +12 MB SAN-TPH AND +6 MB SAN-IPL. SATELLITE IMAGERY SHOWS INCREASING LOW CLOUDS AHEAD OF A WEAKENING COLD FRONT NOW MOVING OVER THE CHANNEL ISLANDS. THE COLD FRONT IS ASSOCIATED WITH A LOW PRESSURE SYSTEM OVER THE NRN GREAT BASIN. ALTHOUGH WE ARE ON THE SOUTHWESTERN PERIPHERY OF THE SYSTEM...SOUTHERN CALIFORNIA WILL BE IMPACTED BY STRONG WESTERLY WINDS TONIGHT THROUGH THURSDAY AS POST FRONTAL WINDS MOVE INTO THE AREA. THE WINDS WILL PEAK DURING THE AFTERNOON ON THU AS THE UPPER LEVEL TROUGH DEEPENS TOWARD THE SW AND THE MID AND UPPER LEVEL WINDS MIX DOWN TO THE SURFACE. MOUNTAIN WAVES LIKELY OVER THE MOUNTAINS AND SURFACING INTO THE DESERTS. WEST WINDS OF 25 TO 35 MPH WITH GUSTS OF 55 TO 65 MPH ARE LIKELY. MOST OF THE MOISTURE AND DYNAMIC FORCING WITH THIS SYSTEM WILL REMAIN WELL TO OUR NORTH...BUT A MOIST BOUNDARY LAYER DEEPENING TO ABOUT 6000 FEET BY THU MORNING COULD BE ENOUGH TO PRODUCE SMALL AMOUNTS OF PRECIPITATION ON THE COASTAL SLPOES AND WEST OF THE MTNS. EARLY FRIDAY MORNING...THE UPPER TROUGH AXIS PASSES TO THE EAST AND THE WINDS QUICKLY SHIFT TO THE NORTH AND NE AS A SFC HIGH MOVES INTO THE GREAT BASIN...SETTING UP STRONG OFFSHORE PRESSURE GRADIENTS. INITIALLY THE STRONG NORTHERLY WINDS WILL FAVOR THE NORTH-SOUTH PASSES THROUGH THE SAN BERNARDINO MOUNTAINS...FUNNELING THROUGH THE CAJON PASS INTO THE NRN INLAND EMPIRE...AND THROUGH THE MORONGO VALLEY INTO THE NORTHERN COACHELLA VALLEY. THEY WILL TRANSITION TO THE EAST-NORTHEAST FRIDAY THROUGH SATURDAY AS THE SURFACE HIGH PRESSURE MOVES SEWD. THE WINDS WILL BE STRONGEST THROUGH THE EAST-WEST PASSES OF RIVERSIDE AND SAN DIEGO COUNTIES WHERE WINDS OF 20-40 MPH WITH GUSTS OVER 60 MPH IN THE WIND PRONE LOCATIONS. THE GUSTY EAST WINDS WILL CONTINUE INTO EARLY SATURDAY. THE DRY OFFSHORE FLOW WILL PUSH THE MARINE LAYER MOISTURE OFFSHORE BY LATE FRI MORNING. SATURDAY AND SUNDAY WILL BE DRY AND WARM WEST OF THE MOUNTAINS AS THE OFFSHORE FLOW CONTINUES AND AN UPPER LEVEL HIGH PRESSURE RIDGE BUILDS OVER THE WEST COAST. EXPECT DAYTIME HIGHS HIGHS IN THE 70S AND 80S WEST OF THE MTNS...WELL ABOVE AVERAGE FOR EARLY MARCH. THE OFFSHORE EVENT ENDS MONDAY WITH COOLING AND A GRADUAL RETURN OF MARINE LAYER CLOUDS TO COASTAL AND VALLEY ZONES TUESDAY AND WEDNESDAY AS THE UPPER RIDGE BREAKS DOWN AND ANOTHER VIGOROUS TROUGH MOVES INTO CALIFORNIA. && .AVIATION... 010500Z...W OF THE MOUNTAINS...BKN/OVC LOW CLOUDS AND STRATUS WILL CONTINUE TO DEVELOP IN COVERAGE AND DEPTH THROUGH AROUND 02/1800Z THURSDAY MORNING. BASES BETWEEN 2-3K FT MSL AND TOPS AROUND 5K FT MSL. LIGHT RAIN AND DRIZZLE ARE POSSIBLE BUT VIS EXPECTED TO STAY P6SM. AFT 02/1800Z SKIES WILL BECOME FEW/SCT AND WESTERLY WINDS WILL STRENGTHEN TO 10 KT GUSTING TO 20 KT ALONG THE COAST...AFFECTING COASTAL AIRPORTS. WINDS SHOULD DIMINISH BETWEEN 03/0200-0400Z. STRONG NORTHEAST WINDS ARE WILL RAMP UP ACROSS THE REGION ON FRIDAY. MOUNTAINS AND DESERTS...LOW CLOUDS WITH BASES 2-4K FT MSL AND TOPS 4-5K FT MSL WILL PERSIST THROUGH THURSDAY...OBSTRUCTING VIS WHERE CLOUDS INTERSECT TERRAIN. WEST WINDS WILL INCREASE OVER THE MOUNTAINS AND DESERTS AFT 02/1800Z. SURFACE WINDS MAY GUST TO 40 OR 50 KT ACROSS THE RIDGE TOPS AND ON ADJACENT DESERT SLOPES. AS MOUNTAINS WAVES SURFACE...EXPECT STRONG UP AND DOWN DRAFTS ALONG WITH LLWS OVER MANY OF THE DESERT AIRPORTS. && .MARINE... WEST-NORTHWEST WINDS WILL INCREASE THURSDAY AFTERNOON OVER THE COASTAL WATERS AND REMAIN STRONG THURSDAY NIGHT BEHIND A WEAK COLD FRONT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR BOTH THE INNER AND OUTER WATERS. MARINERS SHOULD PREPARE FOR FREQUENT WIND GUSTS TO 25 KTS AND ASSOCIATED STEEP WIND WAVES DURING THIS TIME PERIOD. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...HIGH WIND WARNING FROM 10 AM THURSDAY TO 1 AM PST FRIDAY FOR THE COACHELLA VALLEY...RIVERSIDE COUNTY MOUNTAINS...SAN DIEGO COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS. HIGH WIND WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING FOR THE RIVERSIDE COUNTY MOUNTAINS...SAN DIEGO COUNTY MOUNTAINS...SAN DIEGO COUNTY VALLEYS. HIGH WIND WARNING FROM 10 AM TO 10 PM PST THURSDAY FOR THE APPLE AND LUCERNE VALLEYS...SAN BERNARDINO COUNTY MOUNTAINS. WIND ADVISORY UNTIL 10 AM PST THURSDAY FOR THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY. HIGH WIND WATCH FROM LATE THURSDAY NIGHT THROUGH LATE FRIDAY NIGHT FOR THE COACHELLA VALLEY...ORANGE COUNTY COASTAL AREAS...SAN BERNARDINO COUNTY MOUNTAINS...SANTA ANA MOUNTAINS AND FOOTHILLS. HIGH WIND WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY MORNING FOR THE SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE. PZ...SMALL CRAFT ADVISORY FROM NOON THURSDAY TO 6 AM PST FRIDAY FOR THE WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND. SMALL CRAFT ADVISORY FROM 6 PM THURSDAY TO 6 AM PST FRIDAY FOR THE COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT 30 NM. && $$ PUBLIC...PG AVIATION/MARINE...JT