Forecast Discussions mentioning ACARS, received at FSL on 05/01/00

...SYNOPSIS... WEAKENING HIGH PRESSURE WILL ALLOW ONSHORE FLOW TO INCREASE THE DEPTH OF THE MARINE LAYER THIS WEEK. THE FLOW ALOFT IS ALSO SHIFTING TO THE SOUTHWEST. THIS WILL ALLOW HIGH CLOUDS TO MOVE ACROSS THE REGION LATE TODAY AND TONIGHT.

...DISCUSSION... REX BLOCK SYNOPTIC PATTERN SHAPING UP WITH LOW DROPPING SOUTH INTO OVER TEXAS AND EVENTUALLY RETROGRADING ACROSS THE SOUTHWEST UNITED STATES/NORTHERN MEXICO. THE AMPLITUDE OF THE HIGH IS FLATTENED AND THE RIDGE AXIS SHIFTS INLAND UNDER ASSAULT OF SHORT WAVES MOVING ACROSS NE PACIFIC. THE 150 KT PLUS JET FROM THE DATELINE TO 150W LONGITUDE BETWEEN 40N-50N LATITUDE APPEARS TO BE THE DRIVING FORCE FOR THIS. THE OVERALL EFFECTS ON SW CALIFORNIA WEATHER PATTERN ARE SUBTLE BUT GENERALLY LEAD TO ONSHORE FLOW BECOMING DOMINATE FLOW PATTERN...RESULTING IN SLOW INCREASE IN MARINE LAYER DEPTH/COOLING TREND. SATELLITE IMAGERY AND COASTAL METAR REPORTS SHOW PATCHY STRATUS DEVELOPING ALREADY ALONG N BAJA/SAN DIEGO COAST. CLIMATOLOGY WOULD HAVE SUPPORTED A PERIOD OF DENSE FOG THE FIRST NIGHT FOLLOWING THE REVERSAL OF THE FLOW PATTERN. ACARS AND PROFILER DATA UNAVAILABLE AT THIS TIME BUT LATEST KSOX AND KNKX VAD WINDS SHOW SE 15 KT WINDS UP TO 10K FT. THIS MUST BE MECHANISM PROVIDING LIFT TO MARINE LAYER ALREADY. SO MUCH FOR CLIMATOLOGY AS A FORECAST TOOL. ALL THE MODELS SHOW AN INCREASE IN HIGH LEVEL RH TONIGHT AS REMNANTS OF SHORT WAVE TROUGH CURRENTLY ALONG 130W AND ENTRAINED SUBTROPICAL MOISTURE MOVE INLAND. INCLUDED MENTION OF VARIABLE HIGH CLOUDS ALL ZONES FOR TONIGHT VERSUS CLEAR SKIES...AS WELL AS DENSE FOG POSSIBILITY FOR SAN DIEGO INLAND VALLEYS. FOLLOWING COORDINATION CALL INCLUDED MENTION OF BREEZY FOR APPLE/YUCCA VALLEYS TUE AFTERNOON THOUGH MODEL MID LEVEL WIND FIELDS DO NOT SUPPORT THIS.

AS FOR THE EXTENDED OUTLOOK...THE MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THROUGH THURSDAY THEN GO 180 DEGREES OUT OF PHASE AFTER FRIDAY AS FAR AS THE SW UNITED STATES IS CONCERNED. THE EUROPEAN MODELS OPT FOR A TROUGH WHILE THE US MODELS BUILD SUPER RIDGE. DID NOT PERSONALLY LOOK AT THE CANADIAN MODEL BUT PER NWSFO LOX IT SUPPORTS A TROUGH. IN THE PAST IT HAS BEEN A GOOD TIE BREAKER. LOW FORECASTER CONFIDENCE DICTATES NO CHANGE.

SAN 000

.SAN...NONE.

BALFOUR



A FEW HIGH CLOUDS...ASSOCIATED WITH A WEAK SHORTWAVE TROF MOVING THROUGH THE SWLY FLOW ALOFT AND INTO THE PAC NW...ARE DRIFTING OVER OUR REGION THIS MORNING. OTHERWISE...SKIES ARE MOSTLY CLEAR. ANOTHER WEAK IMPULSE WILL SLIDE INTO THE PAC NW AND FAR NRN CA THIS AFTERNOON...BUT ITS AFFECTS ON OUR WEATHER WILL BE RATHER MINOR. THE AIRMASS ALOFT IS NOT FORECAST TO COOL UNTIL TONIGHT AFTER A THIRD WEAK IMPULSE MOVES INLAND. HOWEVER...A FEW DEGREES OF COOLING TODAY IS LIKELY DUE TO A SLIGHTLY STRONGER ONSHORE GRADIENT. A FEW MORE DEGREES OF COOLING IS ON TAP FOR TUESDAY...MAINLY INLAND...AFTER A NIGHT OF WEAK COOL ADVECTION. IT APPEARS SOME STRATUS IS FORMING WELL OFFSHORE THIS MORNING...BUT HIGH CLOUDS ARE MAKING IT DIFFICULT TO DISCERN THE EXTENT OF STRATUS DECK. IF STRATUS DOES DEVELOP OFFSHORE...A MODERATE ONSHORE FLOW WILL BRING IT TO THE COAST AND LOCALLY INLAND. SO FAR...IT APPEARS THE STRATUS IS STILL WELL OFFSHORE...SO WILL MENTION ONLY PATCHY COASTAL LOW CLOUDS IN THE FORECAST FOR THIS MORNING.

SYNOPTIC PATTERN DOES NOT CHANGE MUCH THROUGH MOST OF THIS WEEK. THRU FRIDAY...ALL MEDIUM RANGE MODELS KEEP AN UPPER LOW ANCHORED OVER THE GULF OF ALASKA...WITH WSW...SLIGHTLY CYCLONIC...FLOW ALOFT OVER NRN CA AND A SERIES OF WEAK SHORTWAVES PASSING WELL TO OUR NORTH. SO DON'T EXPECT MUCH CHANGE IN THE WEATHER PICTURE FROM TUESDAY THROUGH FRIDAY. THE EURO...UKMET AND CANADIAN MODELS CONTINUE WITH THE SAME GENERAL PATTERN INTO THE COMING WEEKEND. THE MRF...HOWEVER...BUILDS A STRONG H5 RIDGE OVER THE SWRN U.S. DURING THE WEEKEND. THE LATEST MRF HAS BACKED OFF ON THE RIDGE A BIT...BUT ITS PATTERN CONTINUES TO BE MUCH DIFFERENT THAN THE OTHER MEDIUM RANGE MODELS. THUS...BELIEVE ADVERTISEMENT OF A BIG WARMUP NEXT WEEKEND BASED ON THE MRF IS A BIT PREMATURE. POPS ZERO. DYKEMA

.SFO...TDA...SCA...PIGEON PT TO PT PIEDRAS BLANCAS.

N



AT 09Z...SATELLITE IMAGERY SHOWED A SHORT-WAVE TROUGH ZIPPING THROUGH THE PAC NW WITH ANOTHER ONE RAPIDLY MOVING ACROSS 140W N OF 40N. LOW LEVEL MOISTURE WITH A WEAK FRONT WAS OFFSHORE THIS MORNING. THIS MOISTURE SHOULD PUSH ONTO THE COAST THIS AFTERNOON AND TONIGHT. ETA RH AND OMEGA PROGS INDICATE THE BEST CHANCE FOR -RA TONIGHT. WILL EDGE POPS UP SOME FOR TONIGHT BUT KEEP IT DRY FOR TUESDAY. LOOKS LIKE ANOTHER WEAK SYSTEM APPROACHES THE COAST TUESDAY NIGHT FOR ANOTHER CHANCE OF -RA WED. WILL BROAD BRUSH THE EXTENDED WITH A CHANCE OF SHOWERS AS MODELS INDICATE A BAGGY UPPER TROUGH SAGGING INTO THE AREA THROUGH FRIDAY.

CEC 230 EKA 130 UKI 000.

.EKA...NONE.

DJB



STRONG SHORT-WAVE RIDGE REMAINS IN CONTROL OF CALIFORNIA/S WEATHER THIS MORNING. TEMPERATURES SUNDAY WERE 9-12 DEGREES WARMER THAN SATIRDAY IN THE SAN JOAQUIN VALLEY...UP TO 16 DEGREES WARMER IN THE MOUNTAINS...AND UP TO 11 DEGREES WARMER IN THE KERN COUNTY DESERTS. HIGH TEMPERATURES TODAY SHOULD BE A FEW DEGREES WARMER STILL...WITH THE WARMEST VALLEY SPOTS TOPPING 90.

CHANGES IN THE PATTERN DURING THE NEXT 18-24 HOURS WILL BRING A BRIEF COOLING SPELL TO THE REGION. A SHORT-WAVE TROUGH WILL MOVE INTO THE PACIFIC NORTHWEST TODAY AND ACROSS NORTHERN CALIFORNIA THIS EVENING...FLATTENING THE RIDGE AND BRINGING A PUSH OF MARINE AIR THROUGH THE SACRAMENTO DELTA INTO THE SAN JOAQUIN VALLEY. THE MARINE AIR WILL BRING COOLER TEMPERATURES TUESDAY...WITH VALLEY HIGHS DOWN 6-8 DEGREES. THE DEGREE THAT MOUNTAIN AND DESERT STATIONS COOL OVER THE HEIGHT/THICKNESS FALLS WILL DEPEND ON THE DEPTH OF THE MARINE AIR AND ANY SPILLOVER INTO THE PASSES AND CANYONS.

FOR THE EXTENDED FORECAST PERIOD...THE ECMWF SHOWS GOOD CONTINUITY WITH ANOTHER SHORT-WAVE TROUGH MOVING INTO CALIFORNIA FRIDAY. THE NEW MRF HAS BACKED OFF ON THE RIDGING FOR THE END OF THE WEEK THAT SUNDAY/S RUN INTRODUCED. RATHER...A SERIES OF WEAK IMPULSES WILL KEEP THE RIDGE FLAT THROUGH FRIDAY AND DELAY THE REBOUND IN TEMPERATURES BEHIND THE EXITING TROUGH. AS A RESULT...HAVE BACKED OFF ON WARMING BY A FEW DEGREES FOR THE SECOND HALF OF THE WEEK. THE NEW MRF DOES BRING STRONG RIDGING INTO CALIFORNIA FOR THE FIRST PART OF NEXT WEEK... BUT CONFIDENCE REMAINS SOFT AND WILL WAIT FOR ANOTHER MRF RUN TONIGHT BEFORE RAISING TEMPERATURES FOR DAY 5 BY ANY SIGNIFICANT AMOUNT AS THE EXTENDED FORECAST PERIOD BEGINS TO INCLUDE EARLY NEXT WEEK.

ALL POPS ZERO. SANGER

.HNX...NONE. FAT UB 087/051 079/050 081 90000 BFL UB 087/051 080/049 081 90000 YNP UB 083/045 078/045 079 90000



NO SIGNIFICANT CHANGES TO CURRENT THINKING AND NO UPDATES THIS CYCLE. AS EXPECTED THE TEMPERATURES MADE ANOTHER STRONG UPWARD JUMP TODAY ...WITH A ROBUST WARMING OF ABOUT 8-12 DEGF IN THE SAN JOAQUIN VLLY AND ANOTHER 10-15 DEGF IN THE MOUNTAINS. ANOTHER VERY TRANQUIL NIGHT IS IN STORE FOR THE CWA TONIGHT AS UPPER RIDGE BEGINS TO SHIFT EAST. VERY SLACK PRES GRADIENTS TONIGHT WITH NEARLY CALM WINDS AND CLEAR SKIES WILL BRING GOOD RADIATIONAL COOLING EFFECTS...HOWEVER DEWPOINTS HAVE RISEN SIGNIFICANTLY OVER THE PAST 24 HOURS AND EXPECT MIN TEMPS FOR MOST LOCALES TO BE 3 DEGF OR MORE ABOVE LAST NIGHT. CURRENT PROJECTIONS LOOK ON TRACK. MAX TEMPS MONDAY SHOULD RISE SLIGHTLY HIGHER ESPECIALLY AS WE START OFF WARMER IN THE EARLY MORN.

WSW FLOW ALOFT AND SURFACE ONSHORE PRES GRADS WILL BE INCREASING MON TO TUE AS A SERIES OF SHORTWAVES ARE EJECTED FROM GULF OF ALASKA LOW TOWARD THE PAC NW. ALTHOUGH PATTERN IS NOT THE MOST CONDUCIVE FOR A STRONG MARINE INTRUSION INTO THE CENTRAL/SOUTHERN SJ VALLEY...A DECENT BREEZE THRU THE SAC DELTA REGION LOOKS PROBABLE FOR LATE MON AFTN AND THAT WILL BE ALL IT TAKES FOR LLVL COOLER AIRMASS TO MOVE DOWN INTO SJ VLLY MON NIGHT AND RESULT IN SOME COOLING/DROP IN TEMPS FOR TUESDAY. ONLY SLIGHT COOLING ABV 3KFT TUESDAY WITH A SLIGHT DROP IN THICKNESSES.

OUTLOOK PERIOD...RECENT PROGS SUGGEST THAT ONSHORE FLOW THRU THE SAC DELTA WILL MOST LIKELY CONTINUE TUE AFTN/EVE AND THIS MAY RETARD THE WARMUP/TEMP RECOVERY THAT WAS SLATED FOR WEDNESDAY IN SJV AND LOWER FOOTHILLS. WILL RELAY THIS CONCERN TO MID CREW FOR NEXT EXTENDED ISSUANCE.

.HNX...NONE.

LAVIS



ZONE UPDATE WILL BE ISSUED BY 930 PM TO BUMP UP HIGHS FOR MONDAY A CATEGORY AT MOST INLAND LOCATIONS. NO OTHER CHANGES ANTICIPATED.

VERY QUIET WEATHER PATTERN ACROSS THE FORECAST AREA THIS EVENING. EVENING RAOBS SHOW CONTINUATION OF DRY ATMOSPHERE AND SATELLITE IMAGES DEPICT NEAREST CLOUDS TO BE ABOUT 80 MILES OFFSHORE. SIGNIFICANT WARMING INDICATED AT 950 MB...UP ALMOST 10C IN THE LAST 24 HOURS. PRESSURE PATTERN IS QUITE WEAK ATTM AND NO SIGNIFICANT WINDS ARE BEING OBSERVED EVEN IN THE MOUNTAINS. EXPECT WEAK OFFSHORE GRADIENTS LATER TONIGHT WITH CLEAR SKIES CONTINUING AND NO MARINE STRATUS OR FOG.

INCOMING MODELS APPEAR SIMILAR TO PREVIOUS TRENDS. ONSHORE FLOW STRENGTHENS MONDAY AFTERNOON...BUT ON THE OTHER HAND LOW LEVEL TEMPS INCREASE SLIGHTLY. NET RESULT SHOULD BE A FEW DEGREES OF WARMING FOR DESERTS...MOUNTAINS AND VALLEYS WITH LITTLE CHANGE RIGHT ALONG THE COAST. TEMPS AT IMTERMEDIATE LOCATIONS SUCH AS CQT AND CMA WILL BE A BIT MORE UNPREDICTABLE...DEPENDING ON HOW QUICKLY AND HOW STRONGLY THE SEABREEZE CAN REACH THESE LOCATIONS.

MONDAY NIGHT AND TUESDAY...UPPER RIDGE FLATTENS AS WEAK SYSTEMS MOVE INTO THE PAC NW. ONSHORE GRADIENTS CONTINUE TO INCREASE AS WELL. HOWEVER 850 MB TEMPS CHANGE LITTLE AND 1000-500 THICKNESSES DROP ONLY SLIGHTLY. ALL THIS SHOULD RESULT IN SOME COOLING FOR COASTS AND VALLEYS DUE TO INCREASING MARINE INFLUENCE...BUT LITLE CHANGE FOR MOUNTAINS AND DESERTS...AS CURRENTLY FORECAST. PATCHY LOW CLOUDS AND FOG SHOULD RETURN TO THE COASTAL STRIP MONDAY NIGHT AND TUE MORNING...AND COULD SEE SOME HAZE GET INTO THE VALLEYS TUE AS WELL.

EXTENDED...30/12Z ECMWF HAS SOMEWHAT MORE TROFFING ALONG THE WEST COAST IN THE THU/FRI TIMEFRAME AS COMPARED TO THE 30/00Z MRF FORECAST OF A MIDSUMMER TYPE RIDGE OVER THE SW. COULD SEE A DEEPER MARINE LAYER AND COOLER TEMPS THAN PRESENTLY FORECAST IF THE EC VERIFIES...BUT WILL LEAVE ANY ADJUSTMENTS TO MID SHIFT AFTER VIEWING OF NEW MRF.

LAX 0000. JACOBSON

.LAX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX).



LEADING EDGE OF CIRRUS MAKING ITS WAY ACROSS THIS EVENING WITH THICKER CLOUDS LOOMING ON THE WESTERN HORIZON. MOSTLY MID AND UPPER LEVEL MOISTURE INITIALLY...BUT SUSPECT WITH INCREASE IN LOW LEVEL MOISTURE THAT STRATUS WILL DEVELOP TONIGHT. FRONT IS FALLING APART AS IT APPROACHES THE COAST PER IR SATELLITE IMAGERY. MARINE LAYER WILL CONTINUE TO THICKEN AS NEXT VORT MAX APPROACHES BY 18Z MONDAY. ANY PRECIPITATION WHICH DOES FALL WILL BE LIGHT AND CONFINED TO THE NORTH COAST ZONES. THE NEXT SYSTEM ON WEDNESDAY APPEARS SIMILAR TO MONDAYS. THE BOTTOM LINE IS A PERSISTENT MARINE LAYER WITH MAINLY CLOUDY CONDITIONS ALONG THE COAST AND A WARMUP INLAND TOWARD WEEKS END AS WE GET INTO A MORE ZONAL FLOW WITH AN INCREASE IN 500 MILLIBAR HEIGHTS.

CEC 1100 EKA 1100 UKI 0000.

.EKA...NONE.

OSIENSKY 

AFTERNOON TEMPERATURES ARE 4 TO 9 DEGREES ABOVE SATURDAY AT THIS TIME...IN LINE WITH WHAT WAS FORECAST. AXIS OF THE UPPER RIDGE OF HIGH PRESSURE WILL MOVE EAST OUT OF THE REGION BY MONDAY AS A UPPER TROUGH OF LOW PRESSURE OVER THE EASTERN PACIFIC TREKS TOWARD THE WEST COAST. WITH PROJECTED HEIGHT-FALLS...A LITTLE COOLER AIR ADVECTING IN ...SOME HIGHER CLOUDS IN THE NORTH...AND A BIT OF AN ON-SHORE BREEZE ...MAXIMA WILL SEE A SMALL DIP. THIS TREND WILL CONTINUE ON TUESDAY AND WEDNESDAY AS A SERIES OF SHORT-WAVE TROUGHS MOVE THROUGH THE PACIFIC NORTHWEST...THOUGH NO MEASURABLE RAIN IS EXPECTED TO FALL WITHIN OUR COUNTY WARNING AREA IN ASSOCIATION WITH THESE WEAK WEATHER SYSTEMS. BY THURSDAY AND FRIDAY A RIDGE OF HIGH PRESSURE OVER THE FOUR CORNERS AREAS IN THE UPPER ATMOSPHERE AND OFF THE COAST AT THE SURFACE WILL BEGIN TEMPERATURE RECOVERY WITH HIGHS WARMING TO AS MUCH AS TEN DEGREES ABOVE SEASONAL AVERAGES BY WEEK/S END. Randy Hartley

.STO...NONE.

BLU AB 051/065 048/061 050 69000 RBL BB 050/081 052/080 054 69000 SAC AA 049/080 051/080 050 69000



IT IS COMPLETELY CLEAR ACROSS THE DISTRICT THIS AFTERNOON WITH INLAND TEMPERATURES WARMING INTO THE 70S ALREADY. ALONG THE COAST...TEMPS IN THE LOWER TO MID 60S ARE THE RULE AS A WEAK SEABREEZE HAS ALREADY STARTED. SATELLITE PICTURES SHOW PATCHY LOW CLOUDS LURKING OVER THE EASTERN PACIFIC ABOUT 100 MILES FROM THE COAST. AS THE UPPER TROUGH CONTINUES TO EDGE EASTWARD...LOOK FOR AN INCREASING MARINE LAYER OVER THE AREA BY MONDAY NIGHT. 12Z MODEL GUIDANCE SUGGESTS THIS AS WELL AS THE AVN LOWERS THE PROGGED DEW POINT DEPRESSION BY TUESDAY MORNING ALONG THE COAST AND INLAND. THE WESTERLY SURFACE FLOW IS ALSO EXPECTED TO INCREASE...WITH COOLER DAYTIME TEMPS THE RESULT.

FOR THE EXTENDED PERIOD...THERE IS DECENT AGREEMENT AMONGST THE MEDIUM RANGE PROGS...AT LEAST THROUGH MIDWEEK. PROGS FEATURE A BROAD TROUGH OVER THE EASTERN PACIFIC EXTENDING FROM AN UPPER LOW AROUND 52N/140W. BY FRIDAY...THERE IS A BIT OF VARIANCE IN THE SOLUTIONS WITH THE UK MODEL BRINGING THIS TROUGH INLAND WHILE THE OTHERS HAVE MORE ZONAL FLOW DEPICTED. BY FRIDAY AFTERNOON...THE MAJORITY OF THE PROGS KEEP 500 MB HEIGHTS ABOVE 570 DAM OVER SFO FOR A WARMING TREND BY FRIDAY. POPS ZERO. ANDERSON

.SFO...TNGT...SCA...PT SUR TO PT PIEDRAS BLANCAS AND SFO BAY.



MODELS SEEM TO BE IN FAIRLY GOOD AGREEMENT IN THE NEAR TERM. A WEAK AND DYING FRONT WILL DISSAPATE AS IT MOVES ACROSS OUR AREA MONDAY. DON'T THINK THAT THERE IS MUCH CHANCE OF ANY PRECIP IN OUR CWA AND ANY THAT DOES OCCUR WILL BE EXTREMELY LIGHT. WEDNESDAYS SYSTEM LOOKS VERY SIMILAR TO MONDAYS AND WILL LIKELY FALL APART AND DISSAPATE TOO. TEMPERATURES WILL COOL A BIT WITH THESE SYSTEMS BUT THE MAIN CONCERN FOR OUR REGION WILL BE THE PERSISTENCE OF THE MARINE LAYER WITH THE MOSTLY ONSHORE FLOW. SINCE WE WON'T HAVE ANY STRONG SCOURING ACTION FROM EITHER THE MONDAY OR WEDNESDAY FRONTS WE COULD BE IN FOR A RELATIVELY CLOUDY WEEK. INLAND TEMPERATURES SHOULD BE FINE OVERALL AND WILL WARM NEAR THE END OF THE WEEK BUT COASTAL TEMPS WILL BE MORE DIFFICULT AND DEPENDENT ON THE CLOUD COVER.

SEEMS TO BE SOME DIVERGENCE IN THE LONG RANGE MODELS AT THE END OF THE WEEK AND OVER THE WEEKEND AS THE THICKNESS ADVECTION OVER THE GREAT BASIN AREA VARIES SOMEWHAT. BUT THE TRENDS BETWEEN MRF AND CANADIAN ARE SIMILAR IN THAT MID AND UPPER LEVEL HIGH PRESSURE IS FORECAST TO BUILD FROM THE SOUTHERN PLANES INTO THE GREAT BASIN WILL DEFINETLY AFFECT OUR REGION AND MAY END UP PUSHING WHAT'S LEFT OF OUR STORM TRACK WELL TO THE NORTH AND AT THE SAME TIME INCREASE INLAND TEMPERATURES GREATLY. LOOKS LIKE SUMMER IS AROUND THE CORNER.

CEC 1100 EKA 1100 UKI 0000.

.EKA...NONE.

JFB



IT IS COMPLETELY CLEAR ACROSS THE DISTRICT THIS AFTERNOON WITH INLAND TEMPERATURES WARMING INTO THE 70S ALREADY. ALONG THE COAST...TEMPS IN THE LOWER TO MID 60S ARE THE RULE AS A WEAK SEABREEZE HAS ALREADY STARTED. SATELLITE PICTURES SHOW PATCHY LOW CLOUDS LURKING OVER THE EASTERN PACIFIC ABOUT 100 MILES FROM THE COAST. AS THE UPPER TROUGH CONTINUES TO EDGE EASTWARD...LOOK FOR AN INCREASING MARINE LAYER OVER THE AREA BY MONDAY NIGHT. 12Z MODEL GUIDANCE SUGGESTS THIS AS WELL AS THE AVN LOWERS THE PROGGED DEW POINT DEPRESSION BY TUESDAY MORNING ALONG THE COAST AND INLAND. THE WESTERLY SURFACE FLOW IS ALSO EXPECTED TO INCREASE...WITH COOLER DAYTIME TEMPS THE RESULT.

FOR THE EXTENDED PERIOD...THERE IS DECENT AGREEMENT AMONGST THE MEDIUM RANGE PROGS...AT LEAST THROUGH MIDWEEK. PROGS FEATURE A BROAD TROUGH OVER THE EASTERN PACIFIC EXTENDING FROM AN UPPER LOW AROUND 52N/140W. BY FRIDAY...THERE IS A BIT OF VARIANCE IN THE SOLUTIONS WITH THE UK MODEL BRINGING THIS TROUGH INLAND WHILE THE OTHERS HAVE MORE ZONAL FLOW DEPICTED. BY FRIDAY AFTERNOON...THE MAJORITY OF THE PROGS KEEP 500 MB HEIGHTS ABOVE 570 DAM OVER SFO FOR A WARMING TREND BY FRIDAY. POPS ZERO. ANDERSON

.SFO...TNGT...SCA...PT SUR TO PT PIEDRAS BLANCAS.



UPPER RIDGE TO MOVE EAST DURING THE NEXT 36 HOURS WITH HEIGHTS FLATTENING OVER THE CWA AS WSW FLOW STRENGTHENS OVER THE ERN PAC AND SERIES OF SHORTWAVES GET EJECTED FROM GULF OF ALASKA LOW TOWARD THE PAC NW. PROGS SHOW FIRST WAVE MOVING ASHORE LATE TONIGHT/EARLY MON WITH ANOTHER TARGETED FOR LATE MON AFTERNOON. ASSOCIATED FRONTAL BAND WILL WEAKEN IN THE PROCESS AND IMPACTS ON THE CWA WILL BE DETERMINED BY STRENGTH OF ONSHORE FLOW AND SUBSEQUENT DEEPENING OF MARINE LAYER. ALTHOUGH PATTERN IS NOT THE MOST CONDUCIVE FOR A STRONG MARINE INTRUSION INTO THE CENTRAL/SOUTHERN SJ VALLEY...A SHALLOW INFILTRATION SHOULD OCCUR AND PROVIDE SLIGHT COOLING FOR VALLEY AND ADJACENT FOOTHILL LOCATIONS. SUBSEQUENT TIGHTENING OF SURFACE GRADS SHOULD ALSO RESULT IN RESUMPTION OF AFTERNOON BREEZES THROUGH KERN COUNTY MOUNTAINS/DESERTS.

ALTHOUGH X-SECTIONS SHOW SOME REMNANT MOISTURE CROSSING THE CWA WITH DISSIPATING FRONTAL BAND MON NIGHT/EARLY TUES...MOISTURE APPEARS FAIRLY SHALLOW AND LARGELY ABOVE 600MB SO WILL MAINTAIN MOSTLY CLEAR WORDING IN ZONES AT THIS TIME. OTHER THAN POSSIBLE MARINE INFLUENCE IN VALLEY ZONES...TEMP STRUCTURE SHOWS LITTLE CHANGE MON WITH SOME DYNAMIC COOLING TUES FOR A SLIGHT DECREASE IN TEMPS.

DESPITE MINOR DIFFERENCES...MEDIUM RANGE GUIDANCE CONTS TO INDICATE A QUASI-ZONAL FLOW PREVAILING OVER THE ERN PAC WED-FRI WITH THE FA REMAINING DRY AS ANY EMBEDDED WAVES STAY WELL NORTH OF THE CWA. ALL POPS ZERO.

.HNX...NONE.

FAT UU 053/086 051/079 050 88000 BFL UU 053/086 051/080 050 88000 YNP UU 047/078 045/075 045 88000

JSN



HAPPY MAY DAY. MDLS NOT DOING WELL TONIGHT. BY 06Z ALL RUNNING 4-5 DEGREES TOO SLOW WITH ALL APCHG SYSTEMS...INCLDG THAT MOVG THRU TONIGHT, THE ONE NR 140W AND ONE NR 150W. IS REASONABLE WHEN COMPARING PLOT/ACARS TO MDLS WITH KEY ERRORS IN BOTH APCHG JET ALG 40N W OF 140W...WITH INITIALIZATION ABV 500MB WK. WILL RESORT HEAVILY TO SATELLITE INTERPRETATION TONIGHT. AS SUCH... BAROCLINIC BAND CONTINUING TO STRETCH OVR PAC NW WITH BRIEF DRYING BHD BAND LATER THIS MORNING. YET LOW/MID LVL LAGGING BHD TIL MID MORNING THUS HIR POPS. SSMI DATA REVEALING WITH BAND LIGHT PCPN ALG 150W AT 07Z MOVG E AT RATE OF 7 DEGREES/9 HRS...THUS PUTTING IT INTO WRN WA NOON TUE. DVPG AREA OF PCPN NR 140W IN VIC OF 90KT JET CALCULATED TO ARRIVE CST 18Z...YET CRUX PCPN/INSTBY MOVG INTO OR/SRN WA. APPLYING ALL THAT TO FCST PACKAGE...WILL BOOST POPS ALL AREAS AND REVERSE TIMING OF DRY/WET. AS WELL WILL INTRODUCE LIKELY PCPN INTO TUE PACKAGE. ...XTNDD...GIVEN ERRORS IN TIMING IN SHORT RANGE...HAVE LITTLE CONFIDENCE IN DETAILS OF XTNDD. YET WELL ESTABLISHED LONG WAVE TROF BTWN 140W-170W RMNG STATIONARY AND FEEDING MOISTURE INTO REGION BYD XTNDD. IR IMAGERY SHOWING SPLIT FLOW W OF THE DATELINE WITH CONFLUENCE OF SPLIT SW QUADRANT OF LONG WAVE TROF. MOISTURE SOURCE W OF 150E AND BTWN 25-35N...TO BE SOURCE FOR PACIFIC NW PCPN MIDWEEK AND LIKELY INTO WEEKEND. MOISTURE AMTS NOT IMPRESSIVE...JUST THAT MAY WETNESS. QUERCIAGROSSA

UIL 868 SEA 738 OLM 738

.KATX...VCP21/CSR21...OPERATIONAL .SEW...SCA CST. N 

A FEW MINOR ADJUSTMENTS TO THE UPDATE TNGT. EVENING NLIES AFTER A WARM DAY IN THE WILLAMETTE DECREASING AND THE TREND TO LIGHT SLIES OVERNIGHT...WILL TIDY UP THE WND FCST. NOT MUCH PCPN SO FAR UP NORTH AND ONLY XPCT A FEW HUNDREDTHS AT BEST S OF KSEA. A RATHER WK FNT. MM

UIL 9651 SEA 6531 OLM 7541

.KATX...VCP21/CSR21...OPERATIONAL .SEW...SCA CST. N 

OVERVIEW...LITTLE EASTWARD PROGRESSION APPARENT WITH THE COLD FRONT OFFSHORE. RADAR CONTINUES TO SHOW THE NW COAST BEING BRUSHED WITH AT LEAST SOME MIDLEVEL MOISTURE AND PROBABLY LIGHT PRECIP NEAR TTI. YET THE MOISTURE IS ALSO STREAKED ANTICYCLONICALLY AND SUPPORTS FURTHER WEAKENING AND SLOWNESS OF THE FRONT. MM5 SHOWS WEAK FROPA MON MORNING AND APPEARS REASONABLE. BUT WITH MAIN UPPER LEVEL TROUGH REMAINING OFFSHORE NOT MUCH OF AN ONSHORE PUSH EXPECTED BEHIND THE FRONT. THIS WILL KEEP COOLING AND SHOWER ACTIVITY TO A MINIMUM. BY TUE THINGS DRY OUT AGAIN AHEAD OF NEXT APPROACHING FRONT. EXTENDED...MRF...ECMWF AND NOGAPS ALL SUPPORT SIGNIFICANT TROUGH DEEPENING OFF THE COAST WITH INCREASING SWLY FLOW OVER WA. NEXT FRONT IS A BIT SLOWER THAN PREVIOUS RUNS AND RAIN IS NOT EXPECTED TO START ON THE COAST UNTIL LATE TUE NIGHT. FROPA WILL BE WED MORNING WITH A BETTER PUSH OF MOIST AND COOL AIR LATER WED INTO THU. EXPECT SOME SHOWER ACTIVITY TO CONTINUE INTO FRI. SEASONAL TEMPERATURES. COLMAN UIL 9651 SEA 6531 OLM 7541

.KATX...VCP21/CSR21...OPERATIONAL .SEW...SCA CST. N 

UPPER RIDGE ACROSS THE AREA TODAY WITH WARM TEMPS. MORNING AIRCRAFT SOUNDINGS SHOW 5-8 DEGS F WARMING SURFACE-4K...CURRENT 24HR CHANGE SHOWS TEMPS UP 2-6. TROF APPROACHING 130W WILL CAUSE SOME MINOR THICKNESS FALLS TODAY...WHICH MAY OFFSET CURRENT TRENDS. ZONES HAVE TEMPS UP A COUPLE OF DEGS OVER SUN...AND THIS LOOKS GOOD. OHTERWISE JUST SOME HIGH THIN CIRRUS. SURFACE GRADS WEAK FOR ONLY LIGHT AFTERNOON BREEZES. SHORTWAVE TO MOVE THRU TONITE BRINGING A LITTLE COOLING TUES...MAINLY TO THE VALLEY IN THE FORM OF DELTA PUSH. CURRENT ADVERTISED TMMPS TUES MAY BE TOO LOW BUT WILL ADDRESS THAT IN AFTERNOON PACKAGE. ALL POPS ZERO. BINGHAM

.HNX...NONE.



QUIET DAY ACROSS THE DISTRICT THIS MORNING. MARINE LAYER HAS BEGUN TO MAKE SOME VERY MINOR INROADS THIS MORNING...WITH SOME STRATUS/FOG OVER LONG BEACH AND ACROSS THE CENTRAL COAST. ISSUED NOWCAST EARLIER TO ACCOUNT FOR THIS PATCHY MARINE LAYER...AS IT SHOULD BURN OFF VERY QUICKLY THIS MORNING. SURFACE GRADIENTS ARE MORE ONSHORE THIS MORNING WHICH SHOULD RESULT IN SOME COOLING FOR COASTAL AREAS. HOWEVER... INLAND SECTIONS SHOULD HAVE VERY SIMILAR TEMPS AS SUNDAY.

OVERALL...ZONES HAVE GOOD HANDLE ON EXPECTED SUNNY SKIES AND TEMP TRENDS. DO NOT ANTICIPATE ANY ZONE UPDATES THIS MORNING.

LAX 000. THOMPSON.

.LAX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX).



UPPER RIDGE OVER THE WESTERN U.S. BEGINNING TO FLATTEN OUT AND SHIFT EAST. FIRST SHORT WAVE LIFTING NEWRD ACROSS PUGET SOUND EARLY THIS MORNING WITH A FEW HIGH CLOUDS TRAILING SOUTH INTO NORCAL. NEXT WAVE APPROACHING 40N/140W ATTM WILL SPREAD MORE CLOUDS ACROSS THE NORTHERN PORTION OF THE CWA LATER TODAY AND THIS EVENING. HAVE INCLUDED A SLIGHT CHANCE OF PRECIP ACROSS THE FAR NORTH AS THIS FEATURE MOVES THROUGH...AS SOME INCREASE IN MOISTURE AND INSTABILITY IS INDICATED BY AVN AND ETA. OTHER THAN THAT...SHOULD BE A QUIET WEEK WITH FLAT WESTERLY FLOW ACROSS THE EPAC INTO NORCAL. EXPECT ANOTHER RATHER WARM DAY TODAY MOST AREAS...THEN TEMPS COOL BACK TO NEAR NORMAL THROUGH MIDWEEK AS HEIGHTS ERODE SLIGHTLY AND STRONGER ONSHORE FLOW DEVELOPS. MRF STILL BUILDING A STRONG RIDGE ALONG THE WEST COAST NEXT WEEKEND...BUT THIS LATEST RUN IS NOT AS STRONG WITH THE RIDGE AS THE PREVIOUS TWO. ROWE

.STO...NONE.

BLU UU 065/051 062/048 062 68000 RBL BB 082/056 082/053 081 68110 SAC UU 083/054 081/053 081 68000



...SYNOPSIS... WEAKENING HIGH PRESSURE WILL ALLOW ONSHORE FLOW TO INCREASE THE DEPTH OF THE MARINE LAYER THIS WEEK. THE FLOW ALOFT IS ALSO SHIFTING TO THE SOUTHWEST. THIS WILL ALLOW HIGH CLOUDS TO MOVE ACROSS THE REGION LATE TODAY AND TONIGHT.

...DISCUSSION... REX BLOCK SYNOPTIC PATTERN SHAPING UP WITH LOW DROPPING SOUTH INTO OVER TEXAS AND EVENTUALLY RETROGRADING ACROSS THE SOUTHWEST UNITED STATES/NORTHERN MEXICO. THE AMPLITUDE OF THE HIGH IS FLATTENED AND THE RIDGE AXIS SHIFTS INLAND UNDER ASSAULT OF SHORT WAVES MOVING ACROSS NE PACIFIC. THE 150 KT PLUS JET FROM THE DATELINE TO 150W LONGITUDE BETWEEN 40N-50N LATITUDE APPEARS TO BE THE DRIVING FORCE FOR THIS. THE OVERALL EFFECTS ON SW CALIFORNIA WEATHER PATTERN ARE SUBTLE BUT GENERALLY LEAD TO ONSHORE FLOW BECOMING DOMINATE FLOW PATTERN...RESULTING IN SLOW INCREASE IN MARINE LAYER DEPTH/COOLING TREND. SATELLITE IMAGERY AND COASTAL METAR REPORTS SHOW PATCHY STRATUS DEVELOPING ALREADY ALONG N BAJA/SAN DIEGO COAST. CLIMATOLOGY WOULD HAVE SUPPORTED A PERIOD OF DENSE FOG THE FIRST NIGHT FOLLOWING THE REVERSAL OF THE FLOW PATTERN. ACARS AND PROFILER DATA UNAVAILABLE AT THIS TIME BUT LATEST KSOX AND KNKX VAD WINDS SHOW SE 15 KT WINDS UP TO 10K FT. THIS MUST BE MECHANISM PROVIDING LIFT TO MARINE LAYER ALREADY. SO MUCH FOR CLIMATOLOGY AS A FORECAST TOOL. ALL THE MODELS SHOW AN INCREASE IN HIGH LEVEL RH TONIGHT AS REMNANTS OF SHORT WAVE TROUGH CURRENTLY ALONG 130W AND ENTRAINED SUBTROPICAL MOISTURE MOVE INLAND. INCLUDED MENTION OF VARIABLE HIGH CLOUDS ALL ZONES FOR TONIGHT VERSUS CLEAR SKIES...AS WELL AS DENSE FOG POSSIBILITY FOR SAN DIEGO INLAND VALLEYS. FOLLOWING COORDINATION CALL INCLUDED MENTION OF BREEZY FOR APPLE/YUCCA VALLEYS TUE AFTERNOON THOUGH MODEL MID LEVEL WIND FIELDS DO NOT SUPPORT THIS.

AS FOR THE EXTENDED OUTLOOK...THE MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THROUGH THURSDAY THEN GO 180 DEGREES OUT OF PHASE AFTER FRIDAY AS FAR AS THE SW UNITED STATES IS CONCERNED. THE EUROPEAN MODELS OPT FOR A TROUGH WHILE THE US MODELS BUILD SUPER RIDGE. DID NOT PERSONALLY LOOK AT THE CANADIAN MODEL BUT PER NWSFO LOX IT SUPPORTS A TROUGH. IN THE PAST IT HAS BEEN A GOOD TIE BREAKER. LOW FORECASTER CONFIDENCE DICTATES NO CHANGE.

SAN 000

.SAN...NONE.

BALFOUR



A FEW HIGH CLOUDS...ASSOCIATED WITH A WEAK SHORTWAVE TROF MOVING THROUGH THE SWLY FLOW ALOFT AND INTO THE PAC NW...ARE DRIFTING OVER OUR REGION THIS MORNING. OTHERWISE...SKIES ARE MOSTLY CLEAR. ANOTHER WEAK IMPULSE WILL SLIDE INTO THE PAC NW AND FAR NRN CA THIS AFTERNOON...BUT ITS AFFECTS ON OUR WEATHER WILL BE RATHER MINOR. THE AIRMASS ALOFT IS NOT FORECAST TO COOL UNTIL TONIGHT AFTER A THIRD WEAK IMPULSE MOVES INLAND. HOWEVER...A FEW DEGREES OF COOLING TODAY IS LIKELY DUE TO A SLIGHTLY STRONGER ONSHORE GRADIENT. A FEW MORE DEGREES OF COOLING IS ON TAP FOR TUESDAY...MAINLY INLAND...AFTER A NIGHT OF WEAK COOL ADVECTION. IT APPEARS SOME STRATUS IS FORMING WELL OFFSHORE THIS MORNING...BUT HIGH CLOUDS ARE MAKING IT DIFFICULT TO DISCERN THE EXTENT OF STRATUS DECK. IF STRATUS DOES DEVELOP OFFSHORE...A MODERATE ONSHORE FLOW WILL BRING IT TO THE COAST AND LOCALLY INLAND. SO FAR...IT APPEARS THE STRATUS IS STILL WELL OFFSHORE...SO WILL MENTION ONLY PATCHY COASTAL LOW CLOUDS IN THE FORECAST FOR THIS MORNING.

SYNOPTIC PATTERN DOES NOT CHANGE MUCH THROUGH MOST OF THIS WEEK. THRU FRIDAY...ALL MEDIUM RANGE MODELS KEEP AN UPPER LOW ANCHORED OVER THE GULF OF ALASKA...WITH WSW...SLIGHTLY CYCLONIC...FLOW ALOFT OVER NRN CA AND A SERIES OF WEAK SHORTWAVES PASSING WELL TO OUR NORTH. SO DON'T EXPECT MUCH CHANGE IN THE WEATHER PICTURE FROM TUESDAY THROUGH FRIDAY. THE EURO...UKMET AND CANADIAN MODELS CONTINUE WITH THE SAME GENERAL PATTERN INTO THE COMING WEEKEND. THE MRF...HOWEVER...BUILDS A STRONG H5 RIDGE OVER THE SWRN U.S. DURING THE WEEKEND. THE LATEST MRF HAS BACKED OFF ON THE RIDGE A BIT...BUT ITS PATTERN CONTINUES TO BE MUCH DIFFERENT THAN THE OTHER MEDIUM RANGE MODELS. THUS...BELIEVE ADVERTISEMENT OF A BIG WARMUP NEXT WEEKEND BASED ON THE MRF IS A BIT PREMATURE. POPS ZERO. DYKEMA

.SFO...TDA...SCA...PIGEON PT TO PT PIEDRAS BLANCAS.

N



AT 09Z...SATELLITE IMAGERY SHOWED A SHORT-WAVE TROUGH ZIPPING THROUGH THE PAC NW WITH ANOTHER ONE RAPIDLY MOVING ACROSS 140W N OF 40N. LOW LEVEL MOISTURE WITH A WEAK FRONT WAS OFFSHORE THIS MORNING. THIS MOISTURE SHOULD PUSH ONTO THE COAST THIS AFTERNOON AND TONIGHT. ETA RH AND OMEGA PROGS INDICATE THE BEST CHANCE FOR -RA TONIGHT. WILL EDGE POPS UP SOME FOR TONIGHT BUT KEEP IT DRY FOR TUESDAY. LOOKS LIKE ANOTHER WEAK SYSTEM APPROACHES THE COAST TUESDAY NIGHT FOR ANOTHER CHANCE OF -RA WED. WILL BROAD BRUSH THE EXTENDED WITH A CHANCE OF SHOWERS AS MODELS INDICATE A BAGGY UPPER TROUGH SAGGING INTO THE AREA THROUGH FRIDAY.

CEC 230 EKA 130 UKI 000.

.EKA...NONE.

DJB



STRONG SHORT-WAVE RIDGE REMAINS IN CONTROL OF CALIFORNIA/S WEATHER THIS MORNING. TEMPERATURES SUNDAY WERE 9-12 DEGREES WARMER THAN SATIRDAY IN THE SAN JOAQUIN VALLEY...UP TO 16 DEGREES WARMER IN THE MOUNTAINS...AND UP TO 11 DEGREES WARMER IN THE KERN COUNTY DESERTS. HIGH TEMPERATURES TODAY SHOULD BE A FEW DEGREES WARMER STILL...WITH THE WARMEST VALLEY SPOTS TOPPING 90.

CHANGES IN THE PATTERN DURING THE NEXT 18-24 HOURS WILL BRING A BRIEF COOLING SPELL TO THE REGION. A SHORT-WAVE TROUGH WILL MOVE INTO THE PACIFIC NORTHWEST TODAY AND ACROSS NORTHERN CALIFORNIA THIS EVENING...FLATTENING THE RIDGE AND BRINGING A PUSH OF MARINE AIR THROUGH THE SACRAMENTO DELTA INTO THE SAN JOAQUIN VALLEY. THE MARINE AIR WILL BRING COOLER TEMPERATURES TUESDAY...WITH VALLEY HIGHS DOWN 6-8 DEGREES. THE DEGREE THAT MOUNTAIN AND DESERT STATIONS COOL OVER THE HEIGHT/THICKNESS FALLS WILL DEPEND ON THE DEPTH OF THE MARINE AIR AND ANY SPILLOVER INTO THE PASSES AND CANYONS.

FOR THE EXTENDED FORECAST PERIOD...THE ECMWF SHOWS GOOD CONTINUITY WITH ANOTHER SHORT-WAVE TROUGH MOVING INTO CALIFORNIA FRIDAY. THE NEW MRF HAS BACKED OFF ON THE RIDGING FOR THE END OF THE WEEK THAT SUNDAY/S RUN INTRODUCED. RATHER...A SERIES OF WEAK IMPULSES WILL KEEP THE RIDGE FLAT THROUGH FRIDAY AND DELAY THE REBOUND IN TEMPERATURES BEHIND THE EXITING TROUGH. AS A RESULT...HAVE BACKED OFF ON WARMING BY A FEW DEGREES FOR THE SECOND HALF OF THE WEEK. THE NEW MRF DOES BRING STRONG RIDGING INTO CALIFORNIA FOR THE FIRST PART OF NEXT WEEK... BUT CONFIDENCE REMAINS SOFT AND WILL WAIT FOR ANOTHER MRF RUN TONIGHT BEFORE RAISING TEMPERATURES FOR DAY 5 BY ANY SIGNIFICANT AMOUNT AS THE EXTENDED FORECAST PERIOD BEGINS TO INCLUDE EARLY NEXT WEEK.

ALL POPS ZERO. SANGER

.HNX...NONE. FAT UB 087/051 079/050 081 90000 BFL UB 087/051 080/049 081 90000 YNP UB 083/045 078/045 079 90000



NO SIGNIFICANT CHANGES TO CURRENT THINKING AND NO UPDATES THIS CYCLE. AS EXPECTED THE TEMPERATURES MADE ANOTHER STRONG UPWARD JUMP TODAY ...WITH A ROBUST WARMING OF ABOUT 8-12 DEGF IN THE SAN JOAQUIN VLLY AND ANOTHER 10-15 DEGF IN THE MOUNTAINS. ANOTHER VERY TRANQUIL NIGHT IS IN STORE FOR THE CWA TONIGHT AS UPPER RIDGE BEGINS TO SHIFT EAST. VERY SLACK PRES GRADIENTS TONIGHT WITH NEARLY CALM WINDS AND CLEAR SKIES WILL BRING GOOD RADIATIONAL COOLING EFFECTS...HOWEVER DEWPOINTS HAVE RISEN SIGNIFICANTLY OVER THE PAST 24 HOURS AND EXPECT MIN TEMPS FOR MOST LOCALES TO BE 3 DEGF OR MORE ABOVE LAST NIGHT. CURRENT PROJECTIONS LOOK ON TRACK. MAX TEMPS MONDAY SHOULD RISE SLIGHTLY HIGHER ESPECIALLY AS WE START OFF WARMER IN THE EARLY MORN.

WSW FLOW ALOFT AND SURFACE ONSHORE PRES GRADS WILL BE INCREASING MON TO TUE AS A SERIES OF SHORTWAVES ARE EJECTED FROM GULF OF ALASKA LOW TOWARD THE PAC NW. ALTHOUGH PATTERN IS NOT THE MOST CONDUCIVE FOR A STRONG MARINE INTRUSION INTO THE CENTRAL/SOUTHERN SJ VALLEY...A DECENT BREEZE THRU THE SAC DELTA REGION LOOKS PROBABLE FOR LATE MON AFTN AND THAT WILL BE ALL IT TAKES FOR LLVL COOLER AIRMASS TO MOVE DOWN INTO SJ VLLY MON NIGHT AND RESULT IN SOME COOLING/DROP IN TEMPS FOR TUESDAY. ONLY SLIGHT COOLING ABV 3KFT TUESDAY WITH A SLIGHT DROP IN THICKNESSES.

OUTLOOK PERIOD...RECENT PROGS SUGGEST THAT ONSHORE FLOW THRU THE SAC DELTA WILL MOST LIKELY CONTINUE TUE AFTN/EVE AND THIS MAY RETARD THE WARMUP/TEMP RECOVERY THAT WAS SLATED FOR WEDNESDAY IN SJV AND LOWER FOOTHILLS. WILL RELAY THIS CONCERN TO MID CREW FOR NEXT EXTENDED ISSUANCE.

.HNX...NONE.

LAVIS



ZONE UPDATE WILL BE ISSUED BY 930 PM TO BUMP UP HIGHS FOR MONDAY A CATEGORY AT MOST INLAND LOCATIONS. NO OTHER CHANGES ANTICIPATED.

VERY QUIET WEATHER PATTERN ACROSS THE FORECAST AREA THIS EVENING. EVENING RAOBS SHOW CONTINUATION OF DRY ATMOSPHERE AND SATELLITE IMAGES DEPICT NEAREST CLOUDS TO BE ABOUT 80 MILES OFFSHORE. SIGNIFICANT WARMING INDICATED AT 950 MB...UP ALMOST 10C IN THE LAST 24 HOURS. PRESSURE PATTERN IS QUITE WEAK ATTM AND NO SIGNIFICANT WINDS ARE BEING OBSERVED EVEN IN THE MOUNTAINS. EXPECT WEAK OFFSHORE GRADIENTS LATER TONIGHT WITH CLEAR SKIES CONTINUING AND NO MARINE STRATUS OR FOG.

INCOMING MODELS APPEAR SIMILAR TO PREVIOUS TRENDS. ONSHORE FLOW STRENGTHENS MONDAY AFTERNOON...BUT ON THE OTHER HAND LOW LEVEL TEMPS INCREASE SLIGHTLY. NET RESULT SHOULD BE A FEW DEGREES OF WARMING FOR DESERTS...MOUNTAINS AND VALLEYS WITH LITTLE CHANGE RIGHT ALONG THE COAST. TEMPS AT IMTERMEDIATE LOCATIONS SUCH AS CQT AND CMA WILL BE A BIT MORE UNPREDICTABLE...DEPENDING ON HOW QUICKLY AND HOW STRONGLY THE SEABREEZE CAN REACH THESE LOCATIONS.

MONDAY NIGHT AND TUESDAY...UPPER RIDGE FLATTENS AS WEAK SYSTEMS MOVE INTO THE PAC NW. ONSHORE GRADIENTS CONTINUE TO INCREASE AS WELL. HOWEVER 850 MB TEMPS CHANGE LITTLE AND 1000-500 THICKNESSES DROP ONLY SLIGHTLY. ALL THIS SHOULD RESULT IN SOME COOLING FOR COASTS AND VALLEYS DUE TO INCREASING MARINE INFLUENCE...BUT LITLE CHANGE FOR MOUNTAINS AND DESERTS...AS CURRENTLY FORECAST. PATCHY LOW CLOUDS AND FOG SHOULD RETURN TO THE COASTAL STRIP MONDAY NIGHT AND TUE MORNING...AND COULD SEE SOME HAZE GET INTO THE VALLEYS TUE AS WELL.

EXTENDED...30/12Z ECMWF HAS SOMEWHAT MORE TROFFING ALONG THE WEST COAST IN THE THU/FRI TIMEFRAME AS COMPARED TO THE 30/00Z MRF FORECAST OF A MIDSUMMER TYPE RIDGE OVER THE SW. COULD SEE A DEEPER MARINE LAYER AND COOLER TEMPS THAN PRESENTLY FORECAST IF THE EC VERIFIES...BUT WILL LEAVE ANY ADJUSTMENTS TO MID SHIFT AFTER VIEWING OF NEW MRF.

LAX 0000. JACOBSON

.LAX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX).



LEADING EDGE OF CIRRUS MAKING ITS WAY ACROSS THIS EVENING WITH THICKER CLOUDS LOOMING ON THE WESTERN HORIZON. MOSTLY MID AND UPPER LEVEL MOISTURE INITIALLY...BUT SUSPECT WITH INCREASE IN LOW LEVEL MOISTURE THAT STRATUS WILL DEVELOP TONIGHT. FRONT IS FALLING APART AS IT APPROACHES THE COAST PER IR SATELLITE IMAGERY. MARINE LAYER WILL CONTINUE TO THICKEN AS NEXT VORT MAX APPROACHES BY 18Z MONDAY. ANY PRECIPITATION WHICH DOES FALL WILL BE LIGHT AND CONFINED TO THE NORTH COAST ZONES. THE NEXT SYSTEM ON WEDNESDAY APPEARS SIMILAR TO MONDAYS. THE BOTTOM LINE IS A PERSISTENT MARINE LAYER WITH MAINLY CLOUDY CONDITIONS ALONG THE COAST AND A WARMUP INLAND TOWARD WEEKS END AS WE GET INTO A MORE ZONAL FLOW WITH AN INCREASE IN 500 MILLIBAR HEIGHTS.

CEC 1100 EKA 1100 UKI 0000.

.EKA...NONE.

OSIENSKY