EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDLOX 845 PM PDT WED MAY 3 2000
...SYNOPSIS...
A WEAK CATALINA EDDY WILL BRING NIGHT AND MORNING LOW CLOUDS TO
COASTAL AREAS...OTHERWISE MOSTLY CLEAR THROUGH FRIDAY WITH A GRADUAL
COOLING TREND...AND IN THE MOUNTAINS AND DESERTS LOCALLY BREEZY EACH
AFTERNOON AND EVENING. FOR SATURDAY THROUGH MONDAY...FAIR WITH A
GRADUAL WARMING TREND.
...DISCUSSION...
WK CSTL EDDY TO CONTINUE THE NEXT TWO NIGHTS. LATE AFTERNOON AND
EARLY EVENING ACARS SOUNDINGS SHOW THE BASE OF THE MARINE INVERSION
AROUND 2000 FT ALG THE CST FM LAX TO SAN WITH THE BASE OF THE
INVERSION AROUND 2500 FT IN THE INLAND VLYS (ONT). HEIGHTS ALF
TONIGHT CHANGE LTL...THEN LWR A LTL EACH NIGHT THU NIGHT AND FRI
NIGHT. ACCORDINGLY...LTL DEEPENING OF MARINE LYR IS EXPECTED
OVERNIGHT TONIGHT...THEN SLOW DEEPENING THU NIGHT AND FRI NIGHT.
MAIN DIFFERENCE FM 24 HOURS AGO IS THAT CSTL STRATUS HAS DEVELOPED
AND BEGUN TO SPREAD INLAND ALG THE CST SOONER. DEPTH OF THE
INVERSION IS SUFFICIENT FOR STRATUS TO BE ABLE TO REACH THE INLAND
EMPIRE BY MORNING...HOWEVER PATCHY WORDING MAY BE BETTER FOR
TONIGHT...THEN AREAS THU NIGHT AND FRI NIGHT. MINOR COOLING AT THE
CST SHOULD SPREAD GRADUALLY INLAND THU AND FRI...THEN A GRADUAL
WARMING TREND INLAND FM THE CST SAT THRU MON AS WK UPR RDGG BUILDS
OVR SRN CA. CSTL WATERS REMAIN QUIET WITH ONLY MINOR NW SWELL
CONTINUING.
SAN 000
.SAN...NONE.
MARTIN
INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
AFDLOX 840 PM PDT WED MAY 3 2000
SATELLITE LOOPS SHOW THE UPPER-LEVEL LOW CENTERED NEAR 54N/126W...
WEST OF THE SOUTHERN END OF THE ALASKAN PANHANDLE. SEVERAL VORTICITY
LOBES CONTINUE TO ROTATE AROUND THE LOW WITH THE NEXT SHORT-WAVE
IMPULSE CURRENTLY MOVING ACROSS THE PACIFIC NORTHWEST. THE ONLY
IMPACT FROM THIS SHORT-WAVE HAS BEREN LOCALLY BREEZY CONDITIONS IN
THE SAN JOAQUIN VALLEY AND GUSTS TO 40-45 MPH THROUGH THE TEHACHAPI
PASS AND ONTO THE MOJAVE DESERT. THE MARINE LAYER REMAINS SHALLOW AT
THIS TIME...LESS THAN 2000 FEET DEEP...SO ONLY A FEW DEGREES COOLING
THURSDAY...WITH MORE SIGNIFICANT COOLING FRIDAY AS A STRONGER SHORT-WAVE
TROUGH MOVES ONTO THE WEST COAST THURSDAY NIGHT AND ACROSS CENTRAL
CALIFORNIA DURING THE DAY.
SURFACE PRESSURE GRADIENTS...WHICH HAD BEEN RELAXING A BIT THIS
AFTERNOON...HAVE BEGUN TIGHTENING AGAIN AS THE SHORT-WAVE PASSES TO
THE NORTH. THUS...BREEZY CONDITIONS WILL CONTINUE THROUGH THE
EVENING. THE PRESSURE GRADIENTS BEGIN TO RELAX AFTER 06Z...SO WINDS
SHOULD DIMINISH AFTER MIDNIGHT. WINDS WILL PICK UP AGAIN THURSDAY
AFTERNOO0N AS THE MODELS FORECAST THE PRESSURE GRADIENTS TO AGAIN
TIGHTEN BY 00Z FRIDAY FOR ANOTHER ROUND OF LOCALLY GUSTY WINDS ON
THE WEST SIDE OF THE SAN JOAQUIN VALLEY AND IN THE TEHACHAPI
MOUNTAINS AND KERN DESERTS LATE THURSDAY AFTERNOON AND EVENING.
TEMPERATURES THIS EVENING IN THE SAN JOAQUIN VALLEY ARE RUNNING
SIMILAR TO TUESDAY EVENING...BUT DEW POINTS ARE SEVERAL DEGREES
LOWER. AS THE WINDS SUBSIDE OVERNIGHT...COULD SEE MINIMUMS DIP INTO
THE MID TO UPPER 40S IN THE COLDEST LOCATIONS. THEREFORE...WILL
UPDATE THIS EVENING/S FORECAST TO LOWER MINIMUMS A FEW DEGREES.
ALL POPS ZERO. SANGER
.HNX...NONE.
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
AFDLOX 900 PM PDT WED MAY 3 2000
A STRATUS FIELD IS DRIVING RAPIDLY ASHORE THIS EVENING. MOST OF THE
CLOUDS FORMED OUT OF THE BLUE LATE THIS AFTN AND ARE RIDING A 3.7 MB
SFO-SAC ONSHORE GRADIENT INLAND. EXPECT THE CLOUDS TO FILL MOST OF
OUR VALLEYS OVERNIGHT. WITH THE STRONG MARINE PUSH AND SOMEWHAT
LOWER 500 MB HEIGHTS AND THICKNESSES FORECAST FOR THU...EXPECT TEMPS
TO GO DOWN A FEW DEGREES ON THU IN MOST AREAS EXCEPT ALONG THE
IMMEDIATE COAST. A STRONG BREEZE CURRENTLY BLOWING INTO LIVERMORE
AND THE DELTA WILL CONTINUE ON THU. WITH THE MARINE LAYER AT LEAST
2000 FEET DEEP...EXPECT CLOUDS TO MIX OUT IN MOST IF NOT ALL AREAS
THU AFTN BUT THEY WILL BE BACK THU NIGHT.
THE NEW ETA AGREES WITH THE MORNING RUNS IN BRINGING A RESPECTABLE
VORT MAX INTO OUR REGION LATE THU NIGHT...MAKING LANDFALL AROUND
MIDNIGHT. THIS SYSTEM IS ASSOCIATED WITH THE TROF W AND NW OF 40/130
SEEN ON THE WATER VAPOR PIX AT THIS TIME. THE MODELS DONT FORECAST
ENOUGH MOISTURE WITH THIS SYSTEM TO BRING US SIGNIFICANT RAIN...
THOUGH THERE WILL PROBABLY BE SOME COASTAL DRIZZLE. WITH THIS NEW
INFLUX OF MARINE AIR PLUS A FURTHER DECREASE IN HEIGHTS AND
THICKNESSES...FRI SHOULD BE EVEN COOLER THAN THU OVER THE INTERIOR
OF OUR DISTRICT.
FRI SHOULD BE THE COOLEST DAY IN THIS SEQUENCE. STARTING ON SAT THE
HEIGHTS ARE FORECAST TO BEGIN INCREASING...WITH A SHORT WAVE RIDGE
BUILDING INTO CA SUN/MON. THE MRF HAS MUCH MORE RIDGING THAN THE
EURO/NOGAPS...BUT ALL HAVE HIGH 500 MB HEIGHTS SUN/MON. ONSHORE FLOW
WILL NOT END BUT SHOULD WEAKEN...WITH LOTS OF WARMING INLAND AND A
LITTLE ON THE COAST BY MON. POPS ZERO. MARKKANEN
.SFO...NONE.
N
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
AFDLOX 300 PM PDT WED MAY 03 2000
ONSHORE PRESSURE GRADIENT IS EXPECTED A LITTLE MORE THROUGHOUT THE
REMAINDER OF THE AFTERNOON. SFO-SAC AND SFO-SCK GRADIENT CURRENTLY AT
3.4 MB AT 2 PM. EXPECT DELTA BREEZE TO PICK UP OVER NEXT COUPLE OF
HOURS...BECOMING BREEZY FOR THE CENTRAL VALLEY FOR THIS EVENING. DUE
TO THE STRONG ONSHORE FLOW...I EXPECT SOME LOW CLOUDS TO MAKE IT BACK
INTO THE CENTRAL VALLEY FOR FRIDAY MORNING. IT MAY END UP TAKING A
LITTLE LONGER THAN LAST NIGHT...SINCE LOW CLOUDS HAVE DISSIPATED FROM
THE COAST.
A WEAK TROF IS SWEEPING BY TO THE NORTH WITH A JET STREAK LOCATED
NEAR 40N AND 130 W ALONG THE BASE OF THE TROF. AS THAT ROTATES
THROUGH THE REGION LATE TONIGHT IT MAY BRING SOME SHOWERS TO NORTHERN
SAC VLY AND SURROUNDING MOUNTAINS. CLOUDS SHOULD CLEAR OUT ON
THURSDAY...WITH ANOTHER WEAK WAVE ROTATING THROUGH TO THE NORTH
THURSDAY NIGHT. 850 MB TEMPS DON'T CHANGE THAT MUCH FROM TODAYS
VALUES SO EXPECT THURSDAYS HIGHS TO BE NEAR TODAYS HIGHS. MODELS
INDICATE SOME COOLING WILL OCCUR FRIDAY AS UPPER TROF DEEPENS A
LITTLE MORE ON FRIDAY. DECENT DELTA BREEZE LATE AFTERNOON AND EVENING
SHOULD CONTINUE INTO THE WEEKEND AS TROF IS CURRENTLY PROGGED SLOWLY
DEEPEN OVER AREA FRIDAY AND FRIDAY NIGHT.
CURRENTLY I AM JUST LEAVING SLIGHT CHANCES ACROSS THE NORTHERN SAC
VLY AND IN SIERRA ZONES FOR FRIDAY AND SATURDAY. PROBLEMS WILL BE IN
TIMING OF SHORT WAVES AS THEY ROTATE AROUND THE BASE OF THE
TROF...AND THE EXTENT THAT THE WILL HAVE ON WEATHER PATTERN. IN
GENERAL I EXPECT WE SHOULD SAY DRY MOST OF THE TIME...BECOMING A
LITTLE COOLER AND CONTINUE DELTA BREEZES THROUGH PERIOD. EXTENDED
MODELS CONTINUE TO PUSH BACK TIMING OF RIDGE BUILDING BACK OVER THE
REGION...NOW SHOWING THE RIDGE BUILDING BACK OVER THE AREA LATE
SUNDAY AND MONDAY.
.STO...NONE.
BLU UB 046/060 045/057 045 75100
RBL BB 054/079 053/076 053 75201
SAC UB 050/079 050/077 050 75000
AREA FORECAST DISCUSSION
NWS EUREKA CA
AFDLOX 230 PM PDT WED MAY 3 2000
A FEW SHOWERS ARE STARTING TO MOVE INTO THE RANGE OF THE RADAR THIS
AFTN AS THE S/WV MOVES THROUGH THE AREA. BAROCLINIC BAND IS RAPIDLY
APPROACHING THE COAST AND WITH ALL MODELS SHOWING WEAK LIFT...PVA
AND SUFFICENT MOISTURE...HAVE DECIDED TO GO HIGH CHANCE TONIGHT
ACROSS THE NRN PART OF THE FA. OTHERWISE...WILL GO LOW CHANCE OR
SLIGHT CHANCE POPS FOR THE REMAINDER OF THE FA. H10/H5 THCKS DROP AROUND
10 DM TMRW...BUT WITH MORE SUN INLAND TEMPS SHOULD COOL ONLY A FEW
DEGREES. THEN OVER THE NEXT COUPLE OF DAYS...A SERIES OF FAST MOVING
S/WVS MOVE ACROSS THE AREA IN THE SW FLOW ALOFT. THE STRONGEST OF THE
WAVES WILL BE ON FRIDAY WHICH MAY CAUSE A FEW SHOWERS ACROSS THE
AREA. WILL NEED TO KEEP POPS ON FRIDAY FOR ISOLATED SHOWERS.
OTHERWISE...THESE WAVES WILL NOT BE STRONG ENOUGH TO CAUSE THE
MARINE LAYER TO DISSIPATE...HOWEVER THEY WILL BE ENOUGH TO LIFT THE
MARINE LAYER AND CAUSE DRIZZLE TO FALL ACROSS THE COASTAL AREAS.
WILL THEREFORE HAVE TO KEEP DRIZZLE IN FOR THE FCST PERIOD ACROSS
THE COAST. TEMPS MAY COOL A DEGREE OR TWO MORE ON FRIDAY AS THERE
SHOULD BE A LITTLE MORE CLOUDINESS THAN ON THURSDAY. EVEN THOUGH THE
H5 TEMPS COOL TO NEAR -20C...NONE OF THE MODELS INDICATE ENOUGH
INSTABILITY TO CAUSE ANY INLAND SHOWER/TSTM ACTIVITY ON THU. SNOW
LEVELS ALSO WILL NOT BE A CONCERN AS THEY SHOULD STAY WELL ABOVE
5500 FEET.
FOR THE EXTENDED...WILL KEEP POPS IN FOR SAT AND SUN AS THE AREA
CONTINUES IN CYCLONIC FLOW. WILL GO DRY ON MONDAY AS MRF SHOWS A
RIDGE TO POP UP OVER THE WEST COAST. TEMPS WILL BE SLIGHTLY BELOW
NORMAL ON SAT AND THEN WARM TO ABOVE NORMAL BY MONDAY.
CEC 5202 EKA 5201 UKI 2100.
.EKA...SMALL CRAFT ADVISORY PT ST GEORGE TO PT ARENA OUT 60 NM.
MRD
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
AFDLOX 243 PM PDT WED MAY 3 2000
VISIBLE SATELLITE PICTURE INDICATING COMPLETELY CLEAR SKIES OVER THE
CWA AT THIS TIME WITH THE STRATUS BAND WELL OFFSHORE. WITH A MARINE
LAYER ESTABLISHED OFFSHORE AND A ROBUST ONSHORE SURFACE PRESSURE
GRADIENT AT THIS TIME BETWEEN SFO AND SAC (3.4 MB)...EXPECT LOW
CLOUDS...ETC...TO RETURN INTO THE AREA OVERNIGHT TONIGHT.
SYNOPTICALLY...A BROAD TROUGH REMAINS OVER THE EASTERN PACIFIC WITH
NEARLY ZONAL FLOW FORECAST FOR THE CENTRAL CALIFORNIA COAST THROUGH
THE FORECAST PERIOD. WEAK IMPULSES ARE PROGGED TO BRUSH ACROSS MAINLY
OREGON AND WASHINGTON OVER THE NEXT FEW DAYS WITH ONLY THE TAIL ENDS
OF THESE SYSTEMS REACHING INTO OUR DISTRICT. DURING THE EXTENDED
PERIOD...THE EASTERN PACIFIC TROUGH IS PROGGED TO MOVE ONSHORE LATE
FRIDAY AND SATURDAY. FOR SUNDAY AND MONDAY...MOST OF THE MEDIUM RANGE
FORECAST MODELS BUILD A RIDGE SOUTHWEST OF POINT CONCEPTION FOR A
WARMING TREND FOR LATE IN THE WEEKEND AND EARLY NEXT WEEK. ANDERSON
POPS ZERO.
.SFO...TNGT..SCA...SAN FRANCISCO BAY.
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 145 PM PDT WED MAY 3 2000
NO REAL BIG SURPRISES IN THE WEATHER FORECAST THIS AFTERNOON. TYPICAL
SPRING WEATHER THROUGH SAT WITH NIGHT AND MORNING LOW CLOUDS AND FOG
WITH AFTERNOON CLEARING IN MOST LOCATIONS. FRIDAY MAY BE THE COOLEST
DAY AS A WEAK TROF MOVES INTO CENTRAL CALIFORNIA. THIS WILL DEEPEN THE
MARINE LYR AND POSSIBLY KEEP SKIES OVERCAST LONGER THAN USUAL. BUT IT
DOESN'T LOOK LIKE IT WILL BE A SITUATION WHERE MARINE LYR WILL DEEPEN
SO MUCH THAT SKIES WILL REMAIN CLOUDY ALL DAY. MAIN THING TO WATCH FOR
WILL BE THE STRENGTH OF THE EDDY. LATEST MM5 MODEL INDICATES THE CURRENT
EDDY CIRCULATION WILL STRENGTHEN OVERNIGHT TONIGHT AND INTO TOMORROW BUT
WILL WEAKEN CONSIDERABLY TOMORROW AFTERNOON. THIS SEEMS A LITTLE TOO
SOON GIVEN THE APPROACHING TROF. FOR NOW WILL INDICATE A MOSTLY SUNNY
DAY FRIDAY WITH JUST SOME LINGERING CLOUDS AT THE BEACHES. TEMPS WILL
BE COOLER NEXT COUPLE DAYS, WITH VALLEYS SEEING THE BIGGEST DROP
FRIDAY.
TROF WILL PASS THROUGH THE AREA FRIDAY INTO EARLY SAT WITH TEMPS
REBOUNDING A COUPLE OF DEGREES BY SUN. MRF MOS TEMPS IN THE UPPER 80S
FOR THE VALLEYS SUN IS PROBABLY TOO WARM, BUT WARMING TREND LOOKS GOOD
FOR THE LATTER HALF OF THE WEEKEND AND INTO NEXT WEEK.
LAX 0000. WOFFORD
.LAX...GALE WARNING/SMALL CRAFT ADVISORY (SEE LAXCWFLAX).
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 900 AM PDT WED MAY 3 2000
FORECASTS LOOK TO BE ON TRACK AND EXPECT NO UPDATES THIS MORNING. MAIN
WEATHER FACTOR AS USUAL TODAY IS THE MARINE LYR, WHICH WITH THE HELP
OF THE CATALINA EDDY, HAS DEEPENED AND CONTINUES TO SPREAD NORTHWARD
AND WESTWARD ALONG THE COAST. AS OF THIS WRITING THE CLOUDS EXTEND JUST
ABOUT TO THE LA/VENTURA COUNTY BORDER WITH A FEW STRAGGLING CLOUDS
FURTHER WEST. BY THIS AFTERNOON, THE CLOUDS WILL LIKELY BE MOVING INTO
SOUTHERN SANTA BARBARA COUNTY. ALONG THE CENTRAL COAST, STRONG NW WINDS
HAVE ERODED THE INVERSION AND MARINE LYR CLOUDS ONLY EXIST OVER LAND
AND A FEW MILES OFFSHORE. WEAKER INVERSION ON VBG SOUNDING INDICATES
BURN OFF SHOULD BE FAIRLY QUICK THIS MORNING BUT CLOUDS WILL LIKELY
RETURN AGAIN TONIGHT. THE DIFFERENCE TODAY IS THAT THERE IS NO
EXTENSIVE CLOUD LAYER OFFSHORE TO MOVE IN DURING THE AFTERNOON SO
CLOUDS WILL LIKELY MAKE A MUCH LATER RETURN THAN TUESDAY.
TEMPS WILL BE COOLING OFF SLIGHTLY DUE TO THE MARINE LYR PRESENCE, BUT
TODAY THE MOST NOTICEABLE DECREASE WILL BE ALONG THE COAST AND THE
IMMEDIATE COASTAL PLAIN. VALLEYS WILL STILL BE INTO THE 80S BUT WILL
COOL OFF MORE ON THURSDAY AS MARINE LYR STARTS TO WORK ITS WAY INLAND.
COOLING TREND WILL CONTINUE INTO FRIDAY AS A WEAK TROF MOVES INTO
NORTHERN AND CENTRAL CALIFORNIA. MARINE LYR WILL DEEPEN AND CLOUDS WILL
BE LATER TO CLEAR. THE WEEKEND FORECAST IS A BIT OF A REVERSAL FROM
LAST SATURDAY WHEN THE MRF WAS INDICATING A 590 RIDGE AND 582
THICKNESSES OVER THE AREA FOR THIS WEEKEND. LATEST MODEL RUNS ARE
SUGGESTING A MUCH MORE TYPICAL SPRINGTIME PATTERN WITH NIGHT AND
MORNING LOW CLOUDS AND FOG AND NEAR NORMAL TEMPS. WARMING TREND IS
INDICATED BY SUN AND MON, BUT DON'T WANT TO GET TOO EXCITED ABOUT THIS
YET.
LAX 000. WOFFORD
.LAX...GALE WARNING/SMALL CRAFT ADVISORY (SEE LAXCWFLAX).
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 330 AM PST SUN MAR 5 2000
CURRENTLY THE ENTIRE DISTRICT IS BLANKETED WITH LIGHT SHOWERS. THE
HEAVIER ACTIVITY IN SOUTHEASTERN LOS ANGELES COUNTY HAS MOVED INTO THE
NEIGHBORING DISTRICT AS THE OLD UPPER LOW CENTERED OVER THE COLORADO
RIVER VALLEY ROTATES EAST...BUT THE COLD FRONT ASSOCIATED WITH THE
UPPER TROUGH JUST OFFSHORE IS DRAGGING A SOLID-LOOKING BAND OF RADAR
ECHOES TOWARD THE COAST OF CENTRAL CALIFORNIA. THIS SAME BAND PRODUCED
HEAVY RAIN AT MONTEREY EARLIER...AND LOOKS PRETTY SUBSTANTIAL ON
SATELLITE PICS AS WELL...BUT WITHOUT MANY CURRENT SURFACE OBSERVATIONS
...IT IS DIFFICULT TO ASSESS THE ACTUAL INTENSITY OF THE RAINFALL
UNDERNEATH THE BAND.
MODELS IN PRETTY GOOD AGREEMENT. ALL SHOW THE EASTERN PACIFIC UPPER
TROUGH RAPIDLY MOVING INTO THE DISTRICT AND CUTTING OFF LATER THIS
MORNING...THEN STAYING IN THE AREA THROUGH MONDAY NIGHT. PERIODS OF
RAIN WILL ACCOMPANY SHORTWAVES ROTATING AROUND THE LOW...BUT WITH THE
ACHINGLY COLD AIR ALOFT...AND COPIOUS MOISTURE AT LOW LEVELS...IT SEEMS
LIKELY THAT LIGHT RAIN COULD FALL MUCH OF THE TIME...AS IT HAS BEEN
DOING THIS MORNING OVER MUCH OF THE DISTRICT.
WITH HEIGHTS LIKELY TO DIP BELOW 531 DM BY TONIGHT...SNOW WILL
CERTAINLY FALL IN THE LOCAL MOUNTAINS. CURRENT THINKING ALONG THESE
LINES SEEMS ON TRACK...AND WITH REPORTS OF SIX INCHES OF SNOW JUST EAST
OF THE DISTRICT LAST EVENING WITH LITTLE ON THE RADAR AT THE TIME...OUR
HIGHER ESTIMATES DO NOT SEEM AT ALL EXCESSIVE FOR OVERNIGHT TONIGHT.
THUS...IT IS PRUDENT TO UPGRADE WATCH TO WINTER STORM WARNING FOR THE
MOUNTAINS...AND ISSUE WATCH FOR ANTELOPE VALLEY.
IN THE EXTENDED PERIOD...SKIES WILL START TO CLEAR OVER THE SOUTHLAND
ON TUESDAY...BUT ANOTHER SYSTEM WILL REACH THE DISTRICT ON WEDNESDAY
AND LINGER INTO THURSDAY.
LAX ++8. RYSHKO.
.LAX...WINTER STORM WARNING (SEE LAXWSWLAX).
...WINTER STORM WATCH (SEE LAXWSWLAX).
...FLASH FLOOD WATCH (SEE LAXFFALAX).
...SMALL CRAFT ADVISORY AND GALE WARNINGS (SEE LAXCWFLAX).
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
AFDLOX 900 AM PDT WED MAY 03 2000
AREAS OF MORNING LOW CLOUDS MANAGED TO MAKE IT INTO THE SRN SAC VLY
THIS MORNING. CURRENTLY SATELLITE PICTURE SHOWS LOW CLOUDS RAPIDLY
DISSIPATING FROM THE DELTA AND AREAS OF LOW CLOUDS ON EASTERN END OF
SAC COUNTY SLOWLY EVAPORATING. MORNING PRESSURE GRADIENT SFO-SAC
CURRENTLY AT 1.8 MB UP .5 MB FROM 24HR AGO. ONSHORE PRESSURE GRADIENT
IS EXPECTED TO INCREASE THROUGHOUT THE DAY AND PEAK BY LATE
AFTERNOON/EARLY EVENING. CURRENT WIND FORECAST ARE PROBABLY A LITTLE
ON THE WEAK SIDE BUT WILL WAIT FOR NOW BEFORE MAKING ANY CHANGES.
MORNING SOUNDING SHOWS COOLING OVER YESTERDAY UP TO 1500 FEET. EXPECT
TEMPS TO BE SLIGHTLY COOLER THAN YESTERDAY. CURRENT TEMP FORECAST
LOOKS OK SO WILL NOT MAKE ANY CHANGES. MANY LOCATIONS WITHIN THE
VALLEY SHOULD TOP OUT IN THE UPPER 70S TODAY.
.STO...NONE.
INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
AFDLOX 850 AM PDT WED MAY 3 2000
UPPER LOW CENTER CURRENTLY NEAR 53N/137W WITH A BROAD TROUGH
COVERING THE EAST PACIFIC SOUTHWARD TO ABOUT 30N. SEVERAL
SHORTWAVES ARE ROTATING AROUND THE UPPER LOW...WITH THE LATEST TO
MOVE ONSHORE NOW LIFTING NORTH ACROSS THE PACIFIC NORTHWEST INTO
BRITISH COLUMBIA. THE NEXT UPSTREAM SHORTWAVE IS LOCATED NEAR
40N/136W BEING DRIVEN BY A STRONG UPPER JET AND IS SLATED TO MOVE
ASHORE LATE TONIGHT AND THURSDAY MORNING ACROSS NORTHERN CALIFORNIA
AND OREGON.
IN THE NEAR TERM...ONSHORE PRESSURE GRADIENTS ARE A LITTLE STRONGER
THAN YESTERDAY MORNING WITH SFO-LAS JUST OVER 9MB AT 15Z.
WESTERLY FLOW ALOFT STRENGTHENS SOME TODAY SO EXPECT A LITTLE
BETTER SUPPORT FOR THE ONSHORE BREEZES THIS AFTERNOON BUT NOTHING
MEETING ADVISORY CRITERIA. MODELS SHOWING A SLIGHTLY WARMER LOW LEVEL
THERMAL STRUCTURE ACROSS THE FA TODAY. THE MARINE LAYER IS ABOUT 1700
FEET DEEP THIS MORNING. THIS WAS ENOUGH TO BRING A SHALLOW LAYER OF
MARINE AIR INTO THE CENTRAL SAN JOAQUIN VALLEY LAST NIGHT.
24 HOUR CHANGE SHOWS TEMPERATURES STARTING THE DAY A FEW DEGREES
COOLER ACROSS THE CENTRAL VALLEY BUT THE SHALLOW MARINE AIR SHOULD
MIX QUICKLY AND TEMPERATURES THROUGHOUT THE FA SHOULD BE AT OR
SLIGHTLY HIGHER THAN YESTERDAY. CURRENT FORECAST PACKAGE LOOKS
FINE.
.HNX...NONE.
TAL
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
AFDLOX 833 AM PDT WED MAY 3 2000
THE STRATUS PATTERN THIS MORNING IS A LOT LESS EXTENSIVE THAN
YESTERDAY'S IN THE NORTHERN ZONES WITH MARIN AND CONTRA COSTA
COUNTIES ALMOST COMPLETELY CLOUD-FREE...WHILE THE PENINSULA
HAS ONLY A FEW STRATUS WISPS AT THIS TIME. SOUTHERN ZONES...HOWEVER
...HAVE MORE CLOUDS...ESPECIALLY MONTEREY COUNTY AS THE SALINAS
VALLEY IS COMPLETELY FILLED IN WITH STRATUS. THERE WAS ALSO
APPRECIABLE AMOUNTS OF DRIZZLE AROUND THE MONTEREY BAY OVERNIGHT AND
THIS MORNING. IT WILL LIKELY TAKE A WHILE FOR THE STUFF TO BURN OFF
HERE IN MONTEREY TODAY...BUT THE REST OF THE CWA SHOULD SEE PLENTY OF
SUN. WILL UPDATE ZONES TO MODIFY SKY CONDITIONS AND MAYBE TWEAK A FEW
TEMPERATURES.
MEANWHILE...ZONAL FLOW ALOFT TO CONTINUE OVER THE AREA. A WEAK
TROUGH TO ALIGN WITH THE WEST COAST BY FRIDAY MORNING WHICH WILL
INCREASE THE ALREADY-PRESENT MARINE LAYER ALONG THE COAST AND
INLAND...BUT NOT A LOT OF DYNAMICS THIS FAR SOUTH. ANDERSON
POPS ZERO EXCEPT STS 011.
.SFO...TDA...SCA...SAN FRANCISCO BAY.
AREA FORECAST DISCUSSION
NWS EUREKA CA
AFDLOX 820 AM PDT WED MAY 3 2000
WILL ONLY NEED TO UPDATE TO MAKE SOME COSMETIC CHANGES...OTHERWISE
ZFP SEEMS TO HAVE THE SITUATION HANDLED QUITE WELL. WEAK TROFFINESS
AND PVA THIS MORNING HAS DEEPENED THE MARINE LAYER AND CAUSED
DRIZZLE TO FORM ACROSS MOST OF THE NORTH COAST. THE BAROCLINIC BAND
THAT IS MOVING THROUGH 140W ATTM IS PROGGED BY THE MESOETA TO MOVE
ACROSS THE NRN PART OF THE FA TONITE. LIKELY POPS FOR THIS EVENING
ACROSS THE NORTH CONTINUE TO BE ON TRACK AS THE 12Z ETA CONTINUES TO
SHOW WEAK LIFT AND SUFFICENT MOISTURE AS THE VORT MAX MOVES ACROSS
THE AREA. ONLY DOWNSIDE TO SEEING RAIN THIS AFTN AND THIS EVENING IS
THAT THE BEST PVA AND STAYS TO THE N OF THE AREA AND THE AREA
REMAINS UNDER THE UNFAVORABLE QUAD OF THE JET.
THE MARINE FCST CONTINUES TO LOOK GOOD. THE 18 FT SWELL CURRENTLY AT
BUOY 2 DECAYS TO 14-15 FEET ACROSS THE AREA TONIGHT WHICH IS ALREADY
IN THE FCST. OTHERWISE...WINDS SHOULD NOT BE MUCH OF A FACTOR AS THE
GRADIENT STAYS WEAK.
CEC 572 ACV 372 UKI 021.
.EKA...SMALL CRAFT ADVISORY PT ST GEORGE TO CAPE MENDOCINO OUT 60NM
THIS AFTERNOON AND TONIGHT.
...SMALL CRAFT ADVISORY CAPE MENDOCINO TO PT ARENA OUT 60NM
TONIGHT AND THURSDAY.
MRD
AREA FORECAST DISCUSSION
NWS EUREKA CA...RE-XMTD...
AFDLOX 300 AM PDT WED MAY 3 2000
WEAK FRONT MOVES ONSHORE LATER THIS MORNING FOR CHANCE OF -RA N OF
THE CAPE. ANOTHER WAVE NEAR 140W BETWEEN 38N AND 40N PROGGED BY AVN
MODEL TO ARRIVE THIS AFTERNOON AND EVENING. MODEL OMEGA AND RH FIELDS
DON'T LOOK ALL TO IMPRESSIVE WITH THIS WAVE SO HAVE LOWER THE POPS.
THE APPROACHING FRONT HAS DISRUPTED THE MARINE INVERSION...BUT
SUSPECT AS HIGH PRES BUILDS TOWARD COAST AND 1000-850MB THICKNESS
VALUES CONTINUE TO FALL TONIGHT AND THURSDAY THE MARINE LAYER WILL
DEEPEN AND PUSH INLAND ONCE AGAIN. HAVE ADDED FOG AND DRIZZLE TO
MOST ALL ZONES. WITH NEAR SURFACE FLOW PROGGED BY AVN TO BECOME MORE
NW THUR AFTERNOON WILL MENTION CLEARING IN THE AFTERNOON ZONES 1 AND
3.
MARINE WISE...OFFSHORE BUOYS WERE INDICATING SWELL FROM 13 TO 17 FT
WITH PERIODS OF 13 TO 14 SECONDS. ARRIVAL TIME AND DECAY HEIGHTS WILL
BE TRICKY. HAVE ADJUSTED THE CWF FOR FASTER ARRIVAL OF SWELL TRAIN
AND BOOSTED SWELL FCST N OF THE CAPE TO 14 FT FOR TONIGHT. NWW3 SIG
WAVE HEIGHTS WERE AS MUCH AS 5 FT TOO LOW.
EXTENDED...BAGGY UPPER TROUGH BEGINS LIFTING OUT OF THE AREA FRIDAY.
NO MOISTURE BUT WITH COOL TEMPS ALOFT WILL CONTINUE THE CHC OF SHWRS.
A WET JET DEVELOPS ACROSS THE PAC ALONG 40N FRIDAY NIGHT AND SAT FOR
A CHC OF -RA THROUGH SUNDAY. HEIGHTS AND THICKNESSES RISE SAT AND
SUNDAY FOR SOME WARMING. FOG AND LOW CLOUDS WILL CONTINUE TO BE A
PROBLEM ALONG THE COAST.
CEC 572 ACV 372 UKI 021.
.EKA...SMALL CRAFT ADVISORY PT ST GEORGE TO CAPE MENDOCINO OUT 60NM
THIS AFTERNOON AND TONIGHT.
...SMALL CRAFT ADVISORY CAPE MENDOCINO TO PT ARENA OUT 60NM
TONIGHT AND THURSDAY.
DJB
EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDLOX 330 AM PDT WED MAY 3 2000
...SYNOPSIS...
A COASTAL EDDY WILL SLOWLY DEEPEN THE MARINE LAYER WEST OF THE MOUNTAINS.
THIS WILL RESULT IN LATE NIGHT AND EARLY MORNING CLOUDS AND FOG
REACHING THE INLAND VALLEYS AND A COOLING TREND. FOR THE MOUNTAINS
AND DESERTS LITTLE CHANGE IS EXPECTED WITH FAIR AND WARM WEATHER
THROUGH THURSDAY.
...DISCUSSION...
BASED ON THE MODELS ALONE...A PERSISTENCE FORECAST IS CALLED FOR THE
NEXT TWO DAYS. OVER THE SW CALIFORNIA MOUNTAINS AND DESERT AREAS
THIS SHOULD SUFFICE. I BASELINED THE TEMPERATURE FORECASTS FOR
THESE ZONES ON YESTERDAYS OBSERVED MAX/MIN NUMBERS AND SURFACE
WINDS...THEN MADE MINOR ADJUSTMENTS PER THE 1000-500 MB THICKNESS
CHANGES. WEST OF THE MOUNTAINS...THE POTENTIAL FOR A 8-12 DEGREE
COOL DOWN OVER THE INLAND EMPIRE/SAN DIEGO COUNTY VALLEYS
EXISTS...BASED ON THE PRESENCE OF THE EDDY AND THE DEEPENING MARINE
LAYER. THE QUESTIONS THAT NEED TO BE ANSWERED ARE WILL THE MARINE
AIR SURGE INLAND OR SEEP...AND WHEN WILL THIS OCCUR. THE PRESSURE
GRADIENTS HAVE BEEN RUNNING AROUND +6 MB BETWEEN THE SW COAST AND SE
DESERTS. SINCE THE MODELS DO NOT SIGNIFICANTLY CHANGE THIS
GRADIENT...AND THE KNKX SOUNDINGS HAVE BEEN SHOWING THE MARINE LAYER
DOUBLING IN HEIGHT ABOUT EVERY TWELVE HOURS DURING THE PAST 36
HOURS...A SLOW SEEPAGE SOLUTION SEEMS WARRANTED. THE 03/00Z KNKX
SOUNDING AND METAR CLOUD BASES SINCE THEN IMPLY THE MARINE LAYER IS
CURRENTLY AROUND 1500 FT DEEP. UPSTREAM... THE KVBG SOUNDING AT
03/00Z SHOWED SIGNIFICANT COOLING BETWEEN 1800 AND 3500 FT DURING
THE PAST 24 HOURS. THE SURFACE WINDS AROUND POINT CONCEPTION AND THE
OFFSHORE WATERS ARE NOW SUSTAINED NW 30 KT. THE 925 MB WINDS BOTH
OBSERVED AND FORECAST ARE WNW 10-20 KTS. ADVECTING THE COOLING
DOWNSTREAM AT ABOUT HALF THESE SPEEDS... ASSUMING THEY REPRESENT THE
MEAN LAYER FLOW...YIELDS A TRAVEL TIME OF ABOUT 1 DAY. THIS WOULD
SUPPORT CONTINUED DOUBLING OF THE MARINE LAYER. WEIGHING AGAINST IS
IS THE OBSERVATIONAL EVIDENCE AND CLIMATOLOGY. THE 24 HOUR
TEMPERATURE CHANGES WEST OF THE MOUNTAINS YESTERDAY DID NOT REFLECT
UNIFORM COOLING...SOME AREAS WERE ACTUALLY WARMER...AND EDDY STUDIES
SUPPORT ADVECTING THE MARINE AIR INLAND MORE RAPIDLY...ON THE ORDER
OF 12 HOURS OF LESS. SO...WHEN FACED WITH CONFLICTING GUIDANCE...THE
BEST COURSE OF ACTION IS NO CHANGE. THEREFORE THE CLOUD/TEMPERATURE
FORECAST FOR NEXT 36 HOURS WILL BE GRADUAL INLAND PENETRATION OF THE
MARINE LAYER WITH ABOUT 3 DEGREES COOLING PER DAY. BURNOFF TIMES
ALONG THE COAST ARE EXPECTED TO BE LATER EACH MORNING.
THE MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THROUGH 120 HOURS WITH
ABOUT 60 METER HEIGHT FALLS AT 500 MB ON FRIDAY AS RIDGE TEMPORARILY
FLATTENED...WITH HEIGHTS REBOUNDING ACROSS SW CALIFORNIA SUNDAY TO
AROUND 5820 METERS. LUMPED FRIDAY THROUGH SATURDAY TOGETHER TO SHOW
SLIGHT COOLING/BREEZY CONDITIONS MOUNTAINS AND HIGH DESERTS. AFTER
DAY 5...THE ECMWF AND MRF AGAIN GO 180 DEGREES OUT OF PHASE WITH
EACH OTHER AND THE MRF WANTING TO BUILD ANOTHER SUPER RIDGE...
ALTHOUGH A LITTLE FURTHER EAST EACH SUCCESSIVE RUN. THE CULPRIT
SEEMS TO BE THE PRESENCE OF THE TROPICAL UPPER TROPOSPHERIC TROUGH
AND THE MODEL WANTING TO SPIN UP AN UPPER LOW NEAR BAJA CALIFORNIA.
IF VALID THIS COULD SET THE STAGE FOR DIVERGENCE ALOFT THAT WOULD
AMPLIFY ANY MID LATITUDE TROUGHS MOVING ONSHORE. WILL SEE HOW THIS
WORKS OUT NEXT WEEK.
SAN 000
.SAN...NONE.
BALFOUR