Excessive Heat in California, June 20 to 21, 2008

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
200 PM PDT FRI JUN 20 2008

...VERY HOT TEMPERATURES TO CONTINUE THROUGH SATURDAY...

.SHORT TERM...(TODAY-MONDAY)
HOTTEST DAY YET REALIZED THROUGHOUT THE REGION AS UPPER LEVEL RIDGE
PEAKS...WITH QUITE AMAZING TEMPS THUS FAR. A NORTHEAST WIND WAS
EXPECTED ALONG THE CENTRAL COAST THIS MORNING...BUT IT LASTED LONGER
THAN PREVIOUSLY THOUGHT. AS A RESULT...PLACES LIKE SANTA MARIA AND
SLO SOARED UP TO 108. THE WARMEST VALLEY LOCATIONS STILL LOOK GOOD
TO REACH 110+ BY THE END OF THE DAY. EXCESSIVE HEAT WARNINGS REMAIN
IN PLAY THROUGH EARLY THIS EVENING...AND WENT AHEAD AND UPGRADED THE
WATCHES FOR TOMORROW. TO MAKE CLEAR...THESE WARNINGS ARE UP FOR THE
VERY HOT TEMPERATURES ALONE AND NOT FOR HIGH HUMIDITIES. THE AIR IS
VERY DRY OVERALL...AND HEAT INDEX VALUES ARE ACTUALLY BELOW AMBIENT
AIR TEMPS BECAUSE OF THIS. RED FLAG WARNINGS STILL LOOK GOOD AS
WELL...THANKS TO MANY SINGLE DIGIT HUMIDITY VALUES.

MIN TEMPS WILL BE QUITE WARM AGAIN TONIGHT...AS A STRONG INVERSION
AND INCREDIBLY WARM AIRMASS REMAINS IN PLACE. EXPECTING ANOTHER
ROUND OF NORTHERLY WINDS OVER AND JUST DOWN WIND OF THE MTNS...BUT
NOT EXPECTING THE SAME NORTHEAST WINDS OVER THE CENTRAL COAST. THESE
WINDS SHOULD BE MAINLY BELOW ADVISORY LEVELS...BUT A FEW SPOTS
THROUGH THE I5 CORRIDOR SHOULD SEE GUSTS INTO THE 40 MPH RANGE
AGAIN. EXPECTING DENSE FOG AGAIN ALONG THE IMMEDIATE LA COAST...AND
IT MAY SKIRT INTO THE VTU COAST BY DAY BREAK.

SAT SHOULD BE FAIRLY SIMILAR TO TODAY...THOUGH SOME OF THE IMMEDIATE
COASTAL SITES SHOULD SEE SOME COOLING WITH A BIT STRONGER ONSHORE
PUSH IN THE AFTERNOON. THE CENTRAL COAST SHOULD SEE EXTRA COOLING
THANKS TO A WEAKER NORTHEAST WIND. THE NEW ADDITION TO THE FORECAST
IS A SLIGHT CHANCE OF DRY THUNDERSTORMS FOR SLO AND SBA COUNTY.
CONSIDERING THERE WAS SOME HIGH BASED CONVECTION LAST NIGHT OVER THE
WATERS TO THE NORTH...AND THE NAM SHOWS A SLUG OF 500 MB MOISTURE
OFF THE BAJA COAST SWINGING UP NORTH OF POINT CONCEPTION
TOMORROW...COULD NOT ARGUE AGAINST A SLIGHT CHANCE. THESE POTENTIAL
THUNDERSTORMS WILL LACK PRECIPITATION DUE TO THE INCREDIBLY DRY
LOWER LEVELS...AND WILL BE OF MOST CONCERN TO FIRE WEATHER FOLKS.

SUNDAY WILL BE LIKE SAT WITH SOME NORTHERLY FLOW AND DENSE FOG...BUT
WILL START THE COOLING TREND AS THE RIDGE ALOFT FLATTENS OUT. MOST
SITES WILL STAY RATHER HOT...BUT SHOULD SEE ABOUT 3 TO 6 DEGREES OF
COOLING. THE CENTRAL COAST SHOULD SEE THE MOST COOLING AS NORTHWEST
FLOW WILL PICKUP IN THE AFTERNOON. THIS NORTHWEST FLOW SHOULD ALSO
HELP TO KICK UP A MODERATE SUNDOWNER SUN NIGHT OVER SBA COUNTY. THE
MARINE LAYER SHOULD BE ON THE RISE AS WELL OVERNIGHT...WHICH WHEN
ADDED TO STRENGTHENING ONSHORE GRADS AND LOWERED THICKS...TEMPS
SHOULD SEE ANOTHER HEALTHY DROP ON MON. LA/VTU COAST AND VALLEYS
WILL LIKELY SEE THE MOST COOLING THIS TIME.

.LONG TERM (TUESDAY-FRIDAY)...
THINGS SHOULD SETTLE BACK DOWN TO NORMAL BY TUES...AND REMAIN RATHER
UNCHANGED THROUGH FRI. ONSHORE GRADS AND 950MB TEMPS LOOK TO BE
TYPICAL FOR THIS TIME OF THE YEAR. UPPER LEVEL PATTERN LOOKS FAIRLY
ZONAL TO SOUTHWESTERLY TUE AND WED...WHICH AGAIN POINTS AT TYPICAL
CONDITIONS. THE GFS AND ECMWF BOTH SHOW A VERY WEAK TROUGH DROPPING
DOWN OFF THE CA COAST THU AND FRI...AS A BLOCKING HIGH NUDGES
NORTHWARD OVER NEW MEXICO AND COLORADO. ALTHOUGH THIS PATTERN DOES
NOT LOOK CONDUCIVE TO MUCH TEMP CHANGE...IT DOES ALMOST RESEMBLE A
FAVORABLE PATTERN FOR SOME MOISTURE TO SKIRT UP FROM MEXICO. CURRENT
MODELS ARE BONE DRY...BUT CANNOT HANG TOO MUCH ON THAT AS IT IS TOO
FAR OUT IN TIME. BUT IF SOME CONVECTION FIRES UP IN MEXICO AND
MOISTENS UP THE MID LEVELS...AND THE HIGH PUSHES A BIT FARTHER TO
THE NORTH...WE MIGHT HAVE SOME MOIST SOUTHEAST FLOW TO CONTEND WITH
AND IS CERTAINLY WORTH KEEPING AN EYE ON.

&&

.AVIATION...20/1800Z.

AN UPPER LEVEL RIDGE OF HIGH PRESSURE CENTERED SOUTH WILL PERSIST
WHILE A TROUGH OF LOW PRESSURE UPSTREAM APPROACHES. LIGHT UPPER
LEVEL SOUTHWEST WIND WILL BECOME MODERATE OVER THE AREA BY THE END
OF THE PERIOD. A WEAK ONSHORE PRESSURE GRADIENT WILL EXIST IN THE
AFTERNOON...OTHERWISE A WEAK NORTHERLY PRESSURE GRADIENT WILL
REDEVELOP OVER THE MOUNTAINS OVERNIGHT. BASE OF THE CAPPING
MARINE INVERSION WAS BELOW .3KFT THIS MORNING AND HEIGHT WILL VERY
LIKELY CHANGE LITTLE THROUGH FRIDAY MORNING.

KLAX...THERE IS A CHANCE MARINE STRATUS NEAR SHORE WILL RETURN FOR A
SHORT PERIOD IN THE NEXT FEW HOURS AND AGAIN SATURDAY MORNING.

KBUR...VIRTUALLY CERTAIN CLEAR SKIES BELOW 12KFT WILL PERSIST.

VIRTUALLY CERTAIN - 95-100%
VERY LIKELY       - 80-95%
LIKELY            - 60-80%
CHANCE            - 30-60%
NOT VERY LIKELY   - 20% OR LESS
&&

.LOX WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING (SEE LAXNPWLOX).
RED FLAG WARNING (SEE LAXRFWLOX).

&&

PUBLIC...KITTELL
AVIATION...30

WWW.WEATHER.GOV/LOSANGELES

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
931 AM PDT FRI JUN 20 2008

CAZ034>041-044>047-051>054-059-087-088-211300-
SAN LUIS OBISPO COUNTY CENTRAL COAST-
SANTA BARBARA COUNTY CENTRAL COAST-SANTA YNEZ VALLEY-
SAN LUIS OBISPO COUNTY INTERIOR VALLEYS-CUYAMA VALLEY-
SANTA BARBARA COUNTY SOUTH COAST-VENTURA COUNTY COAST-
LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES-
VENTURA COUNTY INTERIOR VALLEYS-VENTURA COUNTY COASTAL VALLEYS-
SANTA MONICA MOUNTAINS RECREATIONAL AREA-
LOS ANGELES COUNTY VALLEYS-SAN LUIS OBISPO COUNTY MOUNTAINS-
SANTA BARBARA COUNTY MOUNTAINS-VENTURA COUNTY MOUNTAINS-
LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA MONICA RANGE-
ANTELOPE VALLEY-CATALINA ISLAND-SANTA CLARITA VALLEY-
931 AM PDT FRI JUN 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE...TODAY

EXCESSIVE HEAT EXTENDING FROM THE MOUNTAINS TO THE COAST AS WELL AS
AREAS OF EXTREMELY LOW HUMIDITIES WILL PERSIST.

* EXCESSIVE HEAT WARNING.....SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* RED FLAG WARNING...........SEE WWUS86 KLOX - RFWLOX FOR DETAILS *

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

EXCESSIVE HEAT EXTENDING FROM THE MOUNTAINS TO THE COAST AS WELL AS
AREAS OF EXTREMELY LOW HUMIDITIES WILL LIKELY PERSIST THROUGH
SATURDAY.

* EXCESSIVE HEAT WATCH.....SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* RED FLAG WARNING...........SEE WWUS86 KLOX - RFWLOX FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

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