Wildfire in California, August 5 to 8, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
930 AM PDT SAT AUG 5 2006

.UPDATE...WATER VAPOR PIX SHOW WELL DEFINED UPPER LOW OFF THE CA
COAST...WHICH WILL CONTINUE TO MEANDER AROUND 128W/35N TODAY. FT
ORD PROFILER SHOWS DEEP BUT ILL-DEFINED MARINE LAYER...WHICH
BROUGHT STRATUS INLAND TO THE EAST SLOPES OF THE COAST RANGE
BORDERING THE SJV. IMPACT ON COOLING FOR THE VALLEY A LITTLE
UNCLEAR THIS MORNING. ONSHORE COASTAL GRADS ARE VERY WEAK SO NO
GREAT INFLUX OF MARINE AIR SEEN. WILL LEAVE CURRENT FCST ALONE FOR
NOW...BUT FCST MAX TEMPS IN THE SOUTH VALLEY MAY BE SEVERAL DEGS
TOO HIGH BASED ON CURRENT 24 HR TREND. FCSTS FOR REMAINDER OF THE
CWA OK.

.PREVIOUS DISCUSSION...ISSUED 250 AM...
SHORT TERM...FOR THE CENTRAL CALIFORNIA INTERIOR...THE 00Z MODELS
ARE BETTER INITIALIZED CONCERNING THE UPPER-LEVEL LOW THAN THE RUNS
24 HOURS EARLIER...BUT ARE A BIT TOO FAR SOUTH WITH THE SYSTEM.

WITH THE UPPER-LEVEL LOW OFF THE CENTRAL CALIFORNIA COAST...THE FLOW
ALOFT OVER THE CENTRAL CALIFORNIA INTERIOR IS FROM THE SOUTHEAST.
THE GOES WATER-VAPOR LOOP SHOWS DRY UPPER-LEVEL AIR OVER THE
SOUTHERN PART OF THE STATE...AND THIS DRY AIR WILL BE ADVECTED INTO
THE HANFORD WARNING/FORECAST AREA THE NEXT FEW DAYS...FOR MOSTLY
CLEAR SKIES OVER THE REGION. HOWEVER...THERE IS SOME MOISTURE
WRAPPING AROUND THE LOW...AND THIS COULD SPIN INTO THE NORTHERN HALF
OF THE HANFORD WARNING/FORECAST AREA. THE 06Z NAM-12/WRF...WHICH DID
A GOOD JOB WITH THE THUNDERSTORMS THAT DEVELOPED OVER THE SOUTHERN
SIERRA NEVADA FRIDAY...FORECASTS 700-500-MB RELATIVE HUMIDITIES OF
60-80 PERCENT OVER THE SOUTHERN SIERRA NEVADA CREST AT 00Z SUNDAY
WITH SURFACE COMPUTED CAPES OF 1800+ JOULES/KG AND LIFTED INDEXES OF
-4 TO -6. ALTHOUGH THE 06Z NAM-12/WRF RUN HAS LESS AREAL EXTENT OF
THE HIGH MID-LEVEL HUMIDITIES THAN THE 00Z RUN...THESE PARAMETERS
WARRANT CONTINUING THE SLIGHT CHANCE OF AFTERNOON AND EVENING
THUNDERSTORMS OVER THE SOUTHERN SIERRA NEVADA TODAY.

FOR SUNDAY...THE 06Z NAM-12/WRF SHIFTS THE FOCUS OF STRONGEST
CONVECTION NORTH OF YOSEMITE NATIONAL PARK...BUT STILL HAS SURFACE
COMPUTED CAPES PEAKING AROUND 1000 JOULES/KG NEAR KINGS CANYON. THE
BIGGEST CHANGE FROM THE EARLIER RUN IS THAT THE AIRMASS OVER THE
SOUTHERN SIERRA NEVADA NOW IS FORECAST TO BE DRIER...REFLECTING THE
DRY AIR ADVECTION. IF THIS CHANGE PERSISTS IN THE 12Z RUN...THE NEXT
CREW MAY WISH TO REMOVE THE SLIGHT CHANCE POPS FROM THE MOUNTAINS
SUNDAY.

HIGH TEMPERATURES FRIDAY IN THE OUTLYING AREAS OF THE CENTRAL AND
SOUTHERN SAN JOAQUIN VALLEY WERE DOWN 5-6 DEGREES FROM THURSDAY...
REFLECTING THE INFLUX...ALBEIT WEAK...OF MARINE AIR INTO THE SAN
JOAQUIN VALLEY. HOWEVER...THE LARGER CITIES SHOWED LITTLE COOLING...
WITH FRESNO DOWN ONLY 2 DEGREES AND BAKERSFIELD DOWN 3 DEGREES. FOR
TODAY...THE MODELS FORECAST LITTLE CHANGE IN 850-MB TEMPERATURES AND
ONLY SLIGHT FALLS IN 1000-500-MB THICKNESSES. HAVE GONE A DEGREE OR
TWO BELOW PERSISTENCE...ALTHOUGH HAVE ADJUSTED THE URBAN AREAS DOWN
MORE TO BETTER REFLECT TRENDS.

FOR SUNDAY...THE MODELS FORECAST A 2 C COOLING AT 850 MB. CHANGES IN
1000-500-MB THICKNESSES ARE DEPENDENT ON HOW EACH MODEL HANDLES THE
UPPER-LEVEL LOW AS IT MEANDERS OFFSHORE.

THE LOW IS FORECAST TO LIFT NORTHEAST INTO NORTHERN CALIFORNIA
SUNDAY NIGHT AND MONDAY...WITH 1000-500-MB THICKNESSES OVER CENTRAL
CALIFORNIA REBOUNDING BEHIND THE TROUGH AND 850-MB TEMPERATURES
WARMING BY 1 C. HAVE GONE WITH AROUND 2 DEGREES  COOLING SUNDAY...
THEN WARMED TEMPERATURES A DEGREE OR SO MONDAY.

AS THE LOW LIFTS INTO NORTHERN CALIFORNIA...A DRY SOUTHWEST FLOW
ALOFT DEVELOPS OVER CENTRAL CALIFORNIA...ENDING THE THREAT OF
CONVECTION.

.LONG TERM...MONDAY NIGHT THROUGH FRIDAY...MEDIUM RANGE MODELS HAVE
COME INTO BETTER AGREEMENT THIS MORNING. REMNANTS OF WEAK UPPER LEVEL
LOW LIFT OUT OF NRN CA MON NIGHT. THE FOUR CORNERS HIGH IS FORECAST
TO BEGIN BUILDING WESTWARD TUE...THEN CONTINUE TO SLOWLY BUILD INTO
CENTRAL AND SOUTHERN CA WED THRU FRI. MEANWHILE...THE MODELS KEEP A
RATHER BAGGY UPPER LEVEL TROUGH SITUATED OVER THE EASTERN PACIFIC.
IT IS DOUBTFUL THAT THIS TROUGH WILL HAVE MUCH INFLUENCE ON THE
PATTERN OVER THE CENTRAL CA INTERIOR. HOWEVER...ITS PROXIMITY TO
THE CA COAST WILL PROBABLY ENSURE NIGHT AND MORNING STRATUS AT THE
BEACHES ALONG WITH LOCAL AFTN SEABREEZES. FARTHER INLAND...TEMPS
WILL LIKELY UNDERGO A WARMING TREND DURING MID TO LATE WEEK JUST AS
THE MODELS SUGGEST. FRIDAY WILL PROBABLY BE OUR WARMEST DAY WITH MAX
TEMPS AT OR ABOVE THE CENTURY MARK IN MOST SJ VLY LOCALES. ONE THING
THAT BEARS WATCHING LATE IN THE WEEK IS THE NORTHWARD ADVECTION OF
TROPICAL MOISTURE. THE GFS BRINGS SOME OF THIS MOISTURE INTO KERN
COUNTY BY FRIDAY. HOWEVER...THE DEEPEST MOISTURE APPEARS AS THOUGH
IT WILL REMAIN ACROSS SE CA AND AZ SO WILL LEAVE TOKEN POPS OUT OF
THE KERN CO DESERT AND MTNS ON DAY 7 FOR NOW. OTHERWISE...PATTERN
WILL REMAIN DRY THROUGH FRIDAY.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH 12Z SUNDAY. FOR
SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

BINGHAM/SANGER/DURFEE