EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION...CORRECTION
NWS SAN DIEGO CA
AFDMTR 300 AM PDT SUN APR 30 2000
...SYNOPSIS...
HIGH PRESSURE BUILDING OVER THE GREAT BASIN WILL BRING MOSTLY CLEAR
SKIES WITH WARMER DAYS INTO MONDAY. WEAK SANTA ANA WINDS ARE
EXPECTED THIS MORNING BELOW MOUNTAIN CANYONS AND PASSES. ONSHORE
FLOW WILL RETURN TUESDAY THROUGH THURSDAY FOR MORE NIGHT AND MORNING
COASTAL LOW CLOUDS AND COOLER DAYS.
...DISCUSSION...
PER LATEST NCEP MODEL DISCUSSION...PMDHMD...THE MODELS ARE NOT
INITIALIZED WELL IN HANDLING THE DOWNSTREAM TROUGH NOR THE
APPROACHING UPSTREAM SYSTEMS AND THEREFORE CONFIDENCE NOT VERY HIGH
IN MODEL BOTH SHORT AND MEDIUM RANGE SOLUTIONS. NEVERTHELESS...OF
THE 30/00Z MODELS...THE NGM HAD THE STRONGEST LOW LEVEL WIND
FORECAST FOR THE SANTA ANA WIND EVENT THIS MORNING. THE LATEST RUC
AND MESOETA MODELS DO SHOW SUPPORT WITH DOWNWARD VERTICAL VELOCITIES
OF -6 UBAR/SEC AND NE 25 KT WINDS AT 700 MB BETWEEN 09Z AND 15Z. THE
SURFACE PRESSURE GRADIENTS HAVE REVERSED ABOUT 20 MB IN THE PAST 48
HOURS BETWEEN THE N GREAT BASIN AND THE SW CALIFORNIA COAST AND
FORECAST TO BECOME -9 MB BY 12Z. AN 07Z ACARS SOUNDING OUT OF KONT
SHOWED NE 20 KT WINDS HAD LOWERED TO 2500 MSL AND THE KSOX VAD WINDS
HAVE SHOWN E-NE 25 KT WINDS SINCE 07Z ABOVE 4000 FT. BASED ON CLIMATOLOGY
WILL ISSUE NPW FOR WIND PRONE AREAS OF INLAND EMPIRE AND ORANGE
COUNTY THROUGH 9 AM PDT AND BOOST WIND GUSTS ACROSS COACHELLA VALLEY
AND SAN DIEGO COUNTY TO JUST BELOW ADVISORY CRITERIA THROUGH MID
AFTERNOON. WILL DOUBLE CHECK OBSERVATIONS JUST AFTER SUNRISE TO SEE
IF UPDATE WILL BE NEEDED. AS FOR THE LOCALLY GENERATED SWELL...IT
HAS DROPPED ABOUT AS FORECAST AND SHOULD CONTINUE TO DO SO THROUGH
THE DAY. AT 10Z THE INNER BUOY WAVE HEIGHTS WERE STILL AROUND 5 FT
BETWEEN OCEANSIDE AND POINT LOMA...AND WILL PROBABLY REMAIN SO FOR
ANOTHER 8 HOURS...BEFORE DROPPING BELOW 3 FT...BASED ON OUTER BUOYS
STILL REPORTING AROUND 10 FT AND A TRAVEL TIME OF AROUND 10 KTS.
AS FOR THE EXTENDED OUTLOOK...THE MEDIUM RANGE MODELS ARE IN
AGREEMENT THROUGH NEXT FIVE DAYS ON KEEPING A FLAT RIDGE OVER SW
CALIFORNIA WITH 500 MB HEIGHTS NEAR 5820 METERS. AFTER THAT MRF
BUILDS SUPER RIDGE OVER THE SW UNITED STATES. BASED ON MY OPENING
SENTENCE TO ABOVE PARAGRAPH...WOULD RECOMMEND CAUTION AT THIS TIME.
MAIN SUPPORT FOR BUILDING HEIGHTS TO 5940 METERS OVER 4 CORNERS
REGION SEEMS TO COME FROM A SECOND UPSTREAM TROUGH PHASING WITH A
TROPICAL UPPER TROPOSPHERIC TROUGH...WHICH MAY BE THE REMAINDER OF
THE CURRENT TROUGH ALONG 150W AFTER IT CUTOFFS BETWEEN HAWAII AND
BAJA CALIFORNIA. HOWEVER AFTER DAY 4 IT BECOMES INCREASINGLY
DIFFICULT TO FOLLOW THE INITIAL CAUSATIVE EVENTS.
SAN 000
.SAN...WIND ADVISORY THROUGH 9 AM PDT FOR CAZ048-049-057.
WILL ISSUE LAXNPWSAN AROUND 1000 UTC.
BALFOUR
AREA FORECAST DISCUSSION
NWS EUREKA CA
AFDMTR 230 AM PDT SUN APR 30 2000
UPPER RIDGE CURRENTLY OVER THE WEST COAST WILL SHIFT INLAND TODAY
BUT CWA WILL SEE ONE MORE DRY AND MOSTLY SUNNY DAY. CLOUDS SHOULD
INCREASE OVER THE AREA TONIGHT AS A FRONT APPROACHES FROM THE WEST.
MODELS WASH FRONT OUT AS IT MOVES ONSHORE MONDAY MORNING. MOISTURE
IS LIMITED AND UPWARD VERTICAL VELOCITIES ARE FORECAST TO BE WEAK AT
BEST SO DO NOT EXPECT MUCH PRECIP OUT OF THIS SYSTEM. INTERIOR
MENDOCINO COUNTY WILL PROBABLY NOT SEE ANY PRECIP OUT OF THIS EVENT.
IN THE SHORT TERM...SATELLITE SHOWS FOG/LOW CLOUDS HAVE DEVELOPED
OVER MUCH OF COASTAL MENDOCINO COUNTY WITH MORE PATCHY STRATUS IN
HUMBOLDT AND TRINITY COUNTIES. WILL MENTION IN ZONES THIS MORNING.
EXTENDED...TUESDAY LOOKS DRY WITH WEST/SOUTHWEST FLOW OVER THE AREA.
ANOTHER WEAK FRONT SHOULD MOVE THROUGH THE CWA WEDNESDAY BUT THIS
FEATURE ONLY WARRANTS MENTIONING CHANCE POPS OVER THE NORTHERN
ZONES. DRY AGAIN ON THURSDAY ALL AREAS WITH HIGH TEMPS NEAR NORMAL.
SCHNEIDER
CEC 012 EKA 012 UKI 000.
.EKA...NONE.
INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
AFDMTR 220 AM PDT SUN APR 30 2000
TEMPERATURES SATURDAY WERE MOSTLY 6-8 DEGREES WARMER THAN FRIDAY FOR
THE SAN JOAQUIN VALLEY AND 12-15 DEGREES WARMER IN THE MOUNTAINS AS
THE UPPER-LEVEL RIDGE BUILT INTO CALIFORNIA. COLD AIR HAS MIXED OUT
OF THE VALLEY AND WITH ANOTHER 40-50 METER RISE IN 500-MB HEIGHTS
AND 1000-500-MB THICKNESSES...WILL SEE VALLEY TEMPERATURES WARM
ANOTHER 8-10 DEGREES SUNDAY WHILE THE MOUNTAINS WARM 6-8 DEGREES.
THE MODELS ARE IN GOOD AGREEMENT WITH THE RIDGE PERSISTING INTO
MONDAY FOR A FEW MORE DEGREES OF WARMING...THEN THE RIDGE GIVES WAY
MONDAY NIGHT TO A SHORT-WAVE TROUGH THAT WILL MOVE INTO THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA. THIS TROUGH WILL ALLOW MARINE AIR
TO SPILL THROUGH THE SACRAMENTO DELTA INTO THE SAN JOAQUIN VALLEY
LATE MONDAY NIGHT AND TUESDAY FOR COOLER TEMPERATURES. THIS TROUGH
HAS LIMITED MOISTURE...SO ONLY IMPACT WILL BE SOME HIGH CLOUDS AND
BREEZY CONDITIONS.
THE MEDIUM-RANGE MODELS HAVE A WEAK ZONAL FLOW WEDNESDAY OVER THE
REGION IN THE WAKE OF THE TROUGH. THE MRF NOW BUILDS ANOTHER UPPER-
LEVEL RIDGE INTO CALIFORNIA FOR THE WEEKEND WITH A 5900-METER CENTER
AT 500 MB. THIS COULD SEND SAN JOAQUIN VALLEY HIGHS INTO THE 90S...
SHOULD THIS RUN OF THE MRF VERIFY. HOWEVER...PREVIOUS MRF RUNS WERE
BRINGING ANOTHER TROUGH IN ON FRIDAY...AS DOES THE LATEST ECMWF...
WHICH HAS SHOWN BETTER CONTINUITY. AS MAJOR CHANGES IN THE MRF OFTEN
REVERT ON SUBSEQUENT RUNS...WILL LEAVE CURRENT EXTENDED FORECAST
ALONE PENDING TONIGHT/S MRF AND OTHER MEDIUM-RANGE MODEL SOLUTIONS.
ALL POPS ZERO. SANGER
.HNX...NONE.
FAT UU 083/054 085/051 079 90000
BFL UU 082/053 085/049 079 90000
YNP UU 076/043 078/041 075 90000
EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION...CORRECTION
NWS SAN DIEGO CA
AFDMTR 930 PM PDT SAT APR 29 2000
...CORRECTED TO DROP LAXMWSSAN AND ADD LAXSPSSAN...
...SYNOPSIS...
UPPER LEVEL HIGH PRESSURE COMBINED WITH A BUILDING SURFACE HIGH
PRESSURE OVER THE PLATEAU WILL BRING MOSTLY CLEAR SKIES WITH WARMER
DAYS INTO MONDAY. WEAK SANTA ANA WINDS ARE EXPECTED THROUGH AND
BELOW MOUNTAIN CANYONS AND PASSES LATE TONIGHT AND SUNDAY. WEAK
ONSHORE FLOW WILL RETURN TUESDAY THROUGH THURSDAY FOR MORE NIGHT AND
MORNING COASTAL LOW CLOUDS AND COOLER DAYS...OTHERWISE MOSTLY
CLEAR.
...DISCUSSION...
NGM/ETA/AVN ARE IN FOR THE NEXT 24 HRS AND ARE BASICALLY SIMILAR.
ALL SHOW THE OFFSHORE PRESSURE GRADIENTS...HOWEVER THE AVN IS A BIT
WEAKER THAN THE NGM OR ETA. CURRENT CONDITIONS SHOW OFFSHORE FLOW
FIGHTING TO GET ESTABLISHED. ALOFT...THERE IS NOT MUCH TO DRIVE A
STRONG WIND PATTERN. THEREFORE THIS LOOKS TO BE MORE GRADIENT
DRIVEN. THERE SHOULD BE ENOUGH PUNCH TO SEND THE WIND GUSTS INTO
THE 40S BELOW CAJON PASS AND IN SANTA ANA CANYON...HOWEVER NOT FOR
ANY EXTENDED PERIOD OF TIME. THERE COULD ALSO BE LOCAL BLOWING DUST.
I WILL NOT ISSUE A WIND ADVISORY MAINLY DUE TO THE SHORT DURATION OF
VERIFYING WINDS.
THE OFFSHORE PUSH SHOULD RESULT IN AFTERNOON HIGH TEMPERATURES WELL
ABOVE NORMAL SUNDAY...ESPECIALLY COASTAL PLAIN AND COASTAL VALLEYS.
WILL UPDATE ZONES WITH HIGHER TEMPERATURES IN SELECTED ZONES. ALSO
WILL BEEF UP SOME OF THE WINDS.
MONDAY STILL LOOKS ABNORMALLY WARM...ESPECIALLY INLAND. MOUNTAINS
AND DESERTS SHOULD BE WARMER MONDAY THAN ON SUNDAY. BY TUESDAY
MORNING THERE COULD BE SOME RATHER DENSE FOG ALONG THE COAST ALONG
WITH A SIGNIFICANT DROP IN MAXIMUM TEMPERATURES. THE PATTERN BECOMES
MORE AND MORE FAVORABLE INTO THE WEAK FOR SETTING UP THE NORMAL
DIURNAL NIGHT AND MORNING LOW CLOUDS AND FOG PATTERN.
SAN 0000
.SAN...SEE SPECIAL WEATHER STATEMENT FOR SANTA ANA WIND CONDITIONS
...LAXSPSSAN
SMALL
INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
AFDMTR 920 PM PDT SAT APR 29 2000
AFTER FRIDAY/S BIG COOLOFF THE TEMPS HAVE RECOVERED IN A ROBUST
FASHION TODAY WITH READINGS UP FROM 7-9 DEGF IN THE SAN JOAQUIN VLLY
AND 10-15 DEGF IN MOST MOUNTAIN LOCATIONS. A VERY TRANQUIL NIGHT IS
IN PROGRESS OVER THE CWA AS UPPER RIDGE CONTINUES TO BUILD AND PRES
GRADS WEAKEN FURTHER. WITH NEARLY CALM WINDS IN SJ VLLY AND CLEAR
SKIES WE/LL SEE IDEAL RADIATIONAL COOLING EFFECTS TONIGHT. THIS WILL
HELP MINS TO DROP ABOUT AS FAR AS DIURNAL THERMAL RANGES FOR LATE
APRIL WILL ALLOW. GUID MINS CERTAINLY LOOK OVERLY WARM AND
OPTIMISTIC. CURRENT FCST MINS MIGHT EVEN BE JUST A BIT WARM FOR SOME
LOCATIONS...BUT OVERALL THE CURRENT FCST TEMPS LOOK IN THE RIGHT
BALLPARK SO WILL NOT MAKE ANY TWEAKS WITH THIS UPDATE CYCLE. AFTER A
COOLISH START EARLY SUN MORN...THE TEMPS SHOULD MAKE ANOTHER STRONG
UPWARD JUMP DURING THE DAY.
EXTENDED FCST LOOKS OK FOR MONDAY WITH READINGS EDGING SLIGHTLY
HIER. FOR TUE/WED WILL NEED TO BE WATCHING CLOSELY FOR LLVL COOLING
EFFECTS INTO SJ VLLY FLOOR FROM AN INTRUSION OF MARINE AIR INLAND AS
ONSHORE FLOW INCREASES. CURRENT FCST TRENDS LOOK REASONABLE TUE/WED
BY MAY NEED SOME ADJUSTMENT AS WE GET CLOSER.
.HNX...NONE.
LAVIS
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
AFDMTR 900 PM PDT SAT APR 29 2000
NO UPDATES ANTICIPATED THIS EVENING WITH UPPER RIDGE FIRMLY IN
CONTROL OF NORCAL WEATHER. AS TROUGH OUT AROUND 145W DIGS...OUR
HEIGHTS ARE PROGGED TO CONTINUE TO RISE INTO SUNDAY. SLACKENED
SURFACE PRESSURE GRADIENTS WITH WEAK THERMAL TROUGHING INTO THE
COASTAL RANGE SHOULD MAKE FOR A RATHER WARM DAY TOMORROW. IN FACT...
850 MB TEMPS ARE PROGGED TO CLIMB INTO THE MID TEENS C...A SOLID 3-5
DEGREES WARMER THAN TODAY. MIXING THOSE TYPES OF READINGS DOWN A DRY
ADIABAT WOULD YIELDS HIGHS IN THE MID 80S FOR SOME OF THE WARMER
VALLEY LOCALES. WE MAY BE A TAD ON THE COOL SIDE IN THE GOING
ZONES...BUT NOT ENOUGH TO WARRANT AN UPDATE. BETTER ONSHORE
GRADIENTS DEVELOP LATE TOMORROW AND CARRY RIGHT INTO THE FIRST HALF
OF THE UPCOMING WORK WEEK AS SERIES OF WEAK TROUGHS WORK THEIR WAY
THROUGH THE PACIFIC NORTHWEST. THE ASSOCIATED COOL WEATHER MAY BE
SHORT LIVED...ESPECIALLY IF THE MRF IS CORRECT IN BUILDING A STRONG
RIDGE INTO THE FOUR CORNERS REGION. TOO FAR OUT TO GET CARRIED AWAY
AT THIS TIME...BUT WE COULD BE SETTING UP FOR OUR FIRST REAL HOT
WEATHER PATTERN SO FAR THIS SEASON BY WEEKS END.
.STO...NONE
JUSKIE
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDMTR 845 PM PDT SAT APR 29 2000
CONT FORECAST TRENDS FOR CLEAR AND WARM OVER CENTRAL CA CST AND SOCAL
THROUGH MONDAY...THEN GRADUAL RETURN OF COASTAL CLOUDS AND SEASONABLY
COOLER NEXT WEEK WITH INCREASING ONSHORE FLOW.
SATELLITE SHOWS CLEAR SKIES OVER OUR DISTRICT ATTM. GRADIENTS HAVE
WEAKENED A LITTLE SOONER THAT I HAD THOUGHT BUT WINDS MAY STILL BE
GUSTY BELOW PASSES AND CANYONS THRU SUNDAY MORNING.
EVENING MODELS SIMILAR TO PREV RUNS. SURFACE HIGH WILL SPREAD ACROSS
THE WEST COAST AND NW STATES THIS WEEKEND. HIGH PRES WILL BUILD ALOFT
OVER CENTRAL AND SOCAL THROUGH MONDAY...THEN MOVE EASTWARD. LOW PRES
SYSTEM MOVING ACROSS N PACIFIC WILL APPROACH WEST COAST BY MID-WEEK.
LAX 0000. SIMPSON.
.LAX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX).
AREA FORECAST DISCUSSION
NWS EUREKA CA
AFDMTR 830 PM PDT SAT APR 29 2000
PREVIOUS PACKAGE ON TRACK. DEVELOPING TROUGH OUT AT 150W PUSHES EAST
WITH A WEAKENING FRONT APPROACHING THE DISTRICT MONDAY. MOST OF THE
ENERGY SHIFTS WELL NORTH AND WE ARE LEFT WITH A DEEPER MARINE LAYER
...COOLER WITH POSSIBLY SOME DRIZZLE. WEAK SHORTWAVE RIDGING AND DRY
TUESDAY BEFORE NEXT WEAK FRONT ON WEDNESDAY. UNTIL THEN ANOTHER FAIR
DAY AND WARMER ON SUNDAY AS UPPER RIDGE AXIS SLIDES EAST. SEAS DOWN
TO 7 TO 8 FEET THIS EVENING AND WILL CONTINUE TO SLACKEN OVERNIGHT.
CEC 0011 EKA 0011 UKI 0000.
.EKA...NONE.
OSIENSKY
AREA FORECAST DISCUSSION
NWS EUREKA CA
AFDMTR 230 PM PDT SAT APR 29 2000
MAIN CHALLENGE THROUGHOUT THE ENTIRE 5 DAY PACKAGE WILL BE TO
DESCRIBE SKY CONDITIONS. WITH VARIABLE AMOUNTS OF CLOUD COVER AND
INTERMITTENT PERIODS OF MERGING LAYERS AT SEVERAL DEPTHS...SATURATION
WILL INVARIABLY OCCUR SEVERAL TIMES ON WINDWARD SLOPES AND PERHAPS AT
SEA LEVEL. TIMING THE DURATION AND AREAL COVERAGE OF THE THICKEST
CLOUD COVER AND MOISTURE WILL DETERMINE WHETHER OR NOT THE
PRECIPITATION IS VIRGA OR LEGITIMATE RAINFALL BELOW 1000 FT MSL. IN
EITHER CASE...SIGNIFICANT RAINFALL OVER THE NEXT 10 DAYS LOOKS RATHER
BLEAK ACROSS MENDOCINO AND TRINITY COUNTIES.
AN UPPER SHORTWAVE IS SHARPENING A TROUGH AXIS ALONG 155W BETWEEN
30-40N. THERE IS GENERAL AGREEMENT THAT CLOUDINESS GENERATED OUT
AHEAD OF THIS TROUGH AXIS PASSES VERY NEAR THE NW CORNER OF CALIF ON
SUNDAY EVENING AND DEVELOPS MOSTLY CLOUDY SKIES ON SUNDAY NIGHT
AND MONDAY MORNING ACROSS MOST THE AREA. THE CLOUDINESS WILL BE
MAINLY A THICK CIRRUS DECK SUNDAY NIGHT AND TRANSITION TO CASTELLANUS
BY MID MORNING MONDAY AS IT SWEEPS EWD ACROSS NRN CALIF. WILL
INTRODUCING SOME -DZ ALONG CAZ001 AND ISOLD/SLGT CHC OF A -SHRA ALONG
THE WINDWARD COASTAL RANGES...CAZ003/004 FOR UP TO MAYBE 5/100THS IN
A FEW SPOTS.
THIS SYSTEM INCREASES THE DEPTH/BREATH OF THE MARINE LAYER INTO TUES
MORNING. MOISTURE MAY BE SHALLOW ENOUGH TO PROVIDE SOME CLEARING
MONDAY AFTERNOON THRU PORTIONS OF THE INTERIOR...BUT THE INITIAL
MARINE PUSH SHOULD FILL THE INTERIOR VALLEYS WITH ENOUGH MOISTURE TO
KNOCK HI TEMPS DOWN 5 TO 10F ON MONDAY AND DEVELOP SOME VALLEY LOW
CLOUD AND FOG DURING THE MON NITE AND TUESDAY MORNING TIME PERIOD.
THE NORTH COAST MAY SEE VERY LITTLE SUNSHINE ON MONDAY. A SHORTWAVE
RIDGE ON TUES WARMS AND DRIES OUT THE REGION AND SETS THE STAGE FOR
ANOTHER MARINE PUSH AND WEAK FRONT MOVING EAST OF 130W ON WED. THIS
FRONT MAY NEVER MAKE IT SOUTH AND EAST OF CAPE MENDOCINO AND IF THIS
PANS OUT...THU FRI AND SAT ARE THE BEGINNING OF A SUMMER-LIKE WARMING
TREND. CEC 0011 EKA 0011 UKI 0000.
.EKA...NONE.
MJV
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
AFDMTR 250 PM PDT SAT APR 29 2000
AXIS OF UPPER LEVEL RIDGE OF HIGH PRESSURE MOVING THROUGH THE COUNTY
WARNING AREA THIS AFTERNOON/EVENING. TEMPERATURES ARE WARMING
ACCORDINGLY WITH THE AWIPS 24 HOUR CHANGE GRAPHIC SHOWING FROM 7 TO
14 DEGREE INCREASES IN MANY LOCATIONS AT 21Z OVER FRIDAY AT THE SAME
TIME. SURFACE RIDGE CENTERED OVER WESTERN OREGON CONTINUES TO COUPLE
WITH RELATIVELY LOWER PRESSURES OVER SOUTHERN NEVADA RESULTING IN A
PREDOMINATELY NORTHWEST TO SOUTHEAST GRADIENT/FLOW ACROSS THE REGION.
CONTINUED MINOR HEIGHT RISES ACROSS THE DISTRICT SUNDAY WILL FURTHER
THE HIGH TEMPERATURE INCREASES A LITTLE FOR SUNDAY. BY MONDAY THE
FIRST IN A SERIES OF SHORT-WAVE TROUGHS WILL MOVE OUT OF THE GULF OF
ALASKA TOWARD THE PACIFIC NORTHWEST. NOT EXPECTING MUCH MORE THAN
COOLER TEMPERATURES WITH INCREASING CLOUDS IN THE NORTH. THE EXTENDED
OUTLOOK INDICATES MORE MODERATING TEMPERATURES AND BREEZY CONDITIONS
IN THE NORTH ON TUESDAY AND WEDNESDAY AS THE NEXT FEW RIPPLES MOVE
THROUGH BEFORE THE PACIFIC HIGH BUILDS ANOTHER SURFACE RIDGE INTO
OREGON. SOME MAXIMA RECOVERY IS EXPECTED BY THURSDAY. Randy Hartley
STO...NONE.
BLU UA 047/064 048/062 048 69000
RBL UB 047/083 053/081 054 69000
SAC UA 047/080 049/079 050 69000
INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
AFDMTR 240 PM PDT SAT APR 29 2000
UPPER RIDGE WAS SHIFTING ONSHORE THIS AFTERNOON WITH STRONG WARMING
EVIDENT IN SURFACE OBS. ALTHOUGH RIDGE AXIS WILL SHIFT EAST OF THE
DISTRICT LATE TONIGHT/SUN...TEMPS SHOULD CONT AN UPWARD TREND AS
SURFACE THERMAL TROUGH STRENGTHENS AND 850MB TEMPS INCREASE AN
ADDITIONAL 3-4C. LOCAL BREEZES SHOULD CONT THIS EVE THROUGH KERN
COUNTY PASSES IN RESPONSE TO RELATIVELY TIGHT NW GRADIENTS...
HOWEVER SURFACE RIDGE BUILDING INTO THE GREAT BASIN IS ALLOWING LOW
LEVEL WINDS TO VEER OFFSHORE AND DIRECTION SHOULD SWING MORE NELY
AFTER SUNSET. OFFSHORE FLOW WAS ALSO RESULTING IN LOCALLY STRONGER
BREEZES ALONG THE WEST SIDE OF THE CENTRAL/SOUTHERN SJ VALLEY THIS
AFTERNOON...HOWEVER SPEEDS SHOULD DECREASE OVERNIGHT AS VALLEY
INVERSION DEVELOPS.
DESPITE MINOR DIFFERENCES...12Z PROGS ARE SIMILAR SHOWING A PATTERN
CHANGE OVER THE EASTERN PACIFIC DURING THE NEXT 48 HOURS AS GULF OF
ALASKA LOW EJECTS A SERIES OF SHORTWAVES TOWARD THE PAC NW.
STRENGTHENING W-SW FLOW ALOFT WILL ALLOW WEAK FRONTAL BOUNDARIES TO
APPROACH NORCAL LATE SUN NIGHT/MON AND AGAIN WED...HOWEVER TRACK OF
VORTS SHOULD KEEP BULK OF LOW-MID LEVEL MOISTURE AND ANY CAA NORTH
OF THE FA THROUGH AT LEAST MIDWEEK. IMPACTS ON CWA SHOULD BE MINIMAL
...HOWEVER MAY NEED TO MONITOR SOUTHERN EXTENT OF WAVES AND
STRENGTHENING ONSHORE FLOW FOR POSSIBLE INTRUSION OF MARINE AIR INTO
THE VALLEY. ALL POPS ZERO.
.HNX...NONE.
FAT UU 049/086 054/087 054 88000
BFL UU 048/085 053/087 054 88000
YNP UU 044/075 046/077 048 88000
JSN
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
AFDMTR 300 PM PDT SAT APR 29 2000
MODEL DATA IN GOOD AGREEMENT WITH HIGH PRESSURE IN FIRM CONTROL TODAY
AND SUNDAY. THE ONSHORE FLOW WEAKENS A BIT TOMORROW AFTERNOON SO WILL
SLACK OFF SOME ON THE COASTAL WINDS. HEIGHTS AND THICKNESSES REACH
THEIR MAXIMUM ON SUNDAY SO EXPECT A WARMER DAY THAN TODAY WITH CLEAR
SKIES. NEXT LOW PRESSURE TROUGH APPROACHES THE DISTRICT MONDAY
MORNING BUT MAIN ENERGY STAYS WELL TO THE NORTH OF OUR AREA. MAIN
CHANGE WILL BE THE RETURN OF LOW CLOUDS AND MARINE LAYER SO HAVE
REINTRODUCED THEM IN THE FORECAST FOR MONDAY MORNING. BEYOND THAT...
I WOULD NOT BE SURPRISED TO SEE MONDAY END UP AS A MOSTLY CLOUDY DAY
FROM THE MOISTURE THAT WILL SPILL OVER THE AREA WITH THE APPROACHING
TROUGH. THE CHANCE OF RAIN FOR US AT THIS POINT FOR MONDAY THOUGH IS
ZERO. LOOKING TOWARD MIDWEEK ANOTHER SHORTWAVE TROUGH ROTATES THROUGH
CENTRAL CALIFORNIA WEDNESDAY BUT AGAIN FOR US IT SHOULD BE A NO-RAIN
SITUATION WITH JUST A MIXED BAG OF MOSTLY MID AND UPPER LEVEL
MOISTURE MOVING THROUGH THE AREA...OF COURSE THE USUAL COASTAL LOW
CLOUDS WILL BE A GIVEN. LONGER RANGE MODELS IN GOOD AGREEMENT ON THIS
SCENARIO AS THEY ARE FOR THURSDAY WHICH IS SHAPING UP TO BE A SUNNIER
AND WARMER DAY AS HEIGHTS AND THICKNESSES INCREASE NICELY FROM
WEDNESDAY. ALL POPS ZERO. WJK
.SFO...TNGT...SCA...PT ARENA TO PT PIEDRAS BLANCAS AND SFO BAY.
N
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDMTR 200 PM PDT SAT APR 29 2000
CLEAR SKIES AND WARM TEMPS WILL BE THE RULE NEXT 36 TO 48 HOURS.
GRADIENTS TRENDING OFFSHORE AND MUCH WARMER AIR IS ADVECTING IN TO THE
AREA. THUS, DAYTIME TEMPS SUNDAY SHOULD BE VERY WARM JUST ABOUT
EVERYWHERE, INCLUDING THE COASTS. WILL LIKELY GET SOME LOCALLY GUSTY
CANYON WINDS LATER TONIGHT AND SUN BUT NO ADVISORIES EXPECTED AS
GRADIENTS AND SUPPORT FROM ALOFT ARE MARGINAL AT BEST.
SLIGHT COOLING TREND AT THE LOWER ELEVATIONS EXPECTED MONDAY AS
PRESSURE GRADIENTS TREND ONSHORE. THIS COULD BE A TRICKY TEMPERATURE
FORECAST AS TRANSITION DAYS OFTEN ARE. BUT FOR NOW WILL INDICATE 3 TO
8 DEGREES OF COOLING MONDAY AND ANOTHER 5 TO 10 PROBABLY ON TUESDAY AS
A WEAK TROF PASSES TO THE NORTH. THIS TROF WILL BRING A RETURN OF THE
MARINE LYR TO THE COASTAL AREAS TUESDAY AND WEDNESDAY, BUT INVERSION
SHOULDN'T DEEPEN ENOUGH TO BRING LOW CLOUDS TO THE VALLEYS.
MODELS INDICATING AN EVEN BIGGER RIDGE DEVELOPING OVER THE AREA AT THE
END OF NEXT WEEK SO WE COULD BE LOOKING AT A SECOND CONSECUTIVE WARM
WEEKEND.
LAX 0000. WOFFORD
.LAX...GALE WARNING/SMALL CRAFT ADVISORY (SEE LAXCWFLAX).
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDMTR 930 AM PDT SAT APR 29 2000
WINDS HAVE DIMINISHED EVERYWHERE EXCEPT FOR THE COASTAL WATERS WHERE
GALES REMAIN IN EFFECT. LOCALLY GUSTY WINDS ARE STILL OCCURRING IN THE
MOUNTAINS BUT EVERYTHING IS WELL BELOW ADVISORY LEVELS SO DECIDED TO
CANCEL ALL WADS AT 9 AM. WE ARE NOW TRANSITIONING FROM A STRONG NW FLOW
TO A WEAK TO MODERATE OFFSHORE FLOW. MODELS ARE A LITTLE STRONGER WITH
THE NE FLOW THAN THEY WERE FRIDAY MORNING, BUT NOT REALLY ENOUGH TO
MAKE ME WORRY ABOUT WIND ADVISORIES. SURFACE GRADIENTS DON'T GET MUCH
MORE OFFSHORE THAN ABOUT 2 MB AND FLOW ALOFT IS MARGINAL. WHAT THIS
MEANS IS THAT THERE WILL BE SOME CANYON WINDS TONIGHT AND SUN BUT
NOTHING WIDESPREAD AND NOT WORTHY OF ADVISORIES. BUT TEMPS WILL TAKE A
NICE JUMP FROM TODAY'S LEVELS, WHICH IN AND OF THEMSELVES WILL BE A
MARKED INCREASE OVER YESTERDAY. STILL HAVE SOME LINGERING COLD
ADVECTION TO DEAL WITH TODAY SO HIGHER VALLEYS AND MOUNTAINS WILL STILL
BE SOMEWHAT COOL, BUT ON THE WHOLE TEMPS TODAY WILL BE MUCH CLOSER TO
NORMAL. WITH 850 TEMPS RISING AS MUCH AS 15 DEGREES SUNDAY, I EXPECT
AFTERNOON TEMPS TO ROAST, ESPECIALLY IN THE VALLEYS WHERE WE COULD BE
LOOKING AT MID TO UPPER 90S AGAIN AT THE WARMER SPOTS. EVEN COASTAL
AREAS WILL BE QUITE WARM WITH NO MARINE LYR CONCERNS AND A WEAK
OFFSHORE FLOW TO WARM THINGS UP.
MONDAY WILL BE QUITE SIMILAR TO SUN THOUGH PERHAPS A FEW DEGREES
COOLER, ESPECIALLY NEAR THE COAST. A VERY WEAK TROF WILL PASS TO THE
NORTH OF THE AREA BY TUESDAY AND THIS WILL HELP REVERSE THE OFFSHORE
FLOW TO A WEAK ONSHORE FLOW BY LATE MONDAY AFTERNOON BRINGING AN
EARLIER SEA BREEZE. BY TUES, VALLEYS SHOULD START SEEING THE COOLING
TREND BUT PROBABLY NOT ANY MARINE LYR AS TROF SHOULD NOT BE STRONG
ENOUGH TO DEEPEN THE MARINE LYR MUCH BEYOND ABOUT 1000 FEET OR SO.
LAX 000. WOFFORD
.LAX...GALE WARNING (SEE LAXCWFLAX).