Wildfire in California, August 25 to 31, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
930 PM PDT WED AUG 24 2011

.SYNOPSIS...
THE WARMING TREND WILL CONTINUE THROUGHOUT THE REGION FOR THE
REMAINDER OF THIS WEEK DUE TO A BUILDING RIDGE OF HIGH PRESSURE.
UPPER-LEVEL MOISTURE WILL BRING A SLIGHT CHANCE OF SHOWERS ALONG THE
SIERRA NEVADA CREST THIS EVENING.

&&
...MIN TEMPS TONIGHT AND MAX TEMPS THURSDAY AMENDED BASED ON 24-HR
TRENDS...

.DISCUSSION...TEMPS ARE TRENDING A BIT WARMER OVER MUCH OF THE CWA
THIS EVENING COMPARED TO 24 HRS AGO. THE ONLY EXCEPTION IS RIGHT
BELOW PACHECO PASS WHERE SOME OCEAN COOLED AIR IS TRICKLING INTO
WESTERNMOST MERCED COUNTY. OTHERWISE...THE MARINE LAYER ALONG THE
CENTRAL CA COAST REMAINS QUITE SHALLOW...GENERALLY LESS THAN 700
FEET DEEP ACCORDING TO THE LATEST FORT ORD PROFILER. ALTHOUGH ONSHORE
GRADIENTS HAVE INCREASED BY A FEW MB SINCE THIS TIME YESTERDAY
AND WILL REMAIN MODERATELY STRONG THROUGH FRIDAY...THE MARINE LAYER
ALONG THE COAST IS NOT LIKELY TO DEEPEN MUCH...IF AT ALL...TO BRING
COOLER AIR INTO THE SJ VLY DURING THE NEXT 2-3 DAYS.

INSTEAD...A VERY STRONG RIDGE OF HIGH PRESSURE ALOFT CENTERED OVER
THE FOUR CORNERS REGION WILL DOMINATE OUR PATTERN THROUGH THE END
OF THIS WEEK. IT BROUGHT TRIPLE DIGIT HEAT TO THE KERN COUNTY DESERT
AND MUCH OF THE SJ VLY THIS AFTERNOON AND WILL LIKELY DO SO AGAIN
THURSDAY AND FRIDAY. INTERESTING TO NOTE THAT MOS GUIDANCE IS TRENDING
SLIGHTLY COOLER IN THE SJ VLY DURING THIS PERIOD BUT THIS DOES NOT
MAKE METEOROLOGICAL SENSE AS THE MODELS FORECAST A DEGREE OR TWO OF
WARMING AT 850 MB THURSDAY WITH LITTLE CHANGE FRIDAY AND KEEP 500 MB
HEIGHTS AT OR ABOVE 590 DM. HENCE...THURSDAY SHOULD BE AS HOT AS
TODAY...IF NOT SLIGHTLY HOTTER...IN MOST AREAS WITH LITTLE CHANGE
FRIDAY.

ADDITIONALLY...A SLIGHTLY DRIER AND MORE STABLE AIRMASS HAS MOVED
INTO THE CWA. ITS PRESENCE HAS DEFINITELY MINIMIZED CONVECTIVE
DEVELOPMENT ALONG THE SIERRA CREST THIS AFTERNOON COMPARED TO
YESTERDAY. THE NEXT 2-3 DAYS WILL PROBABLY BRING LITTLE MORE THAN
SOME AFTERNOON CUMULUS ALONG THE SIERRA CREST AS THE FOUR CORNERS
RIDGE REMAINS FIRMLY IN CONTROL.

THE MODELS ARE IN VERY GOOD AGREEMENT AND FORECAST THE FOUR CORNERS
RIDGE TO DOMINATE OUR WEATHER PATTERN THROUGH MONDAY. HENCE...
TRIPLE DIGIT HEAT WILL LIKELY PERSIST THROUGHOUT THE SJ VLY AND THE
KERN COUNTY DESERT DURING THIS PERIOD. MOS GUIDANCE APPEARS TO BE
TOO COOL AND FEEL IT MAY BE HEAVILY WEIGHTED WITH CLIMATOLOGY.
EVEN DURING THE PAST COUPLE OF DAYS...MAX TEMPS HAVE FARED SLIGHTLY
HIGHER THAN MOS GUIDANCE...ESP IN THE SJ VLY...SO MAX TEMPS MAY NEED
TO BE BUMPED UP A BIT IN THE 3 TO 5 DAY PERIOD.

THE GOOD NEWS...AT LEAST FOR THOSE WHO DISLIKE HOT WEATHER...IS THAT
THE MODELS BREAK DOWN THE RIDGE BY THE MIDDLE OF NEXT WEEK AND BRING
A WEAK UPPER LEVEL TROUGH INTO THE PAC NW. IN TURN...THIS SHOULD COOL
TEMPS TO AT LEAST NORMAL BY NEXT WEDNESDAY.

&&

.PREV DISCUSSION... /ISSUED 202 PM PDT WED AUG 24 2011/

DISCUSSION...MOSTLY SUNNY SKIES PREVAILING ACORSS OUR AREA TODAY
AS AN UPPER LOW OFF THE NORCAL COAST CONTINUES TO TRACK NORTHWARD
AND TAKE IT/S MOISTURE ALONG WITH IT. MEANWHILE...AN UPPER HIGH
PRESSURE CENTER OVER THE SOUTHERN ROCKIES HAS STRENGTHENED TODAY
RESULTING IN INCREASING HEIGHTS AND THICKNESSES. AS A
RESULT...TEMPERATURES ACROSS MOST OF OUR AREA ARE RUNNING 3-5 DEG
F ABOVE YDAY AND ARE ON TRACK TO REACH THE TRIPLE DIGITS ACROSS
THE SAN JOAQUIN VALLEY...LOWER SOUTHERN SIERRA FOOTHILLS AND THE
KERN COUNTY DESERTS. CONVECTION SO FAR TODAY HAS NOT BEEN AS
PRONOUNCED AS IT WAS YDAY. JUST A FEW ELEVATED BUILDUPS NEAR THE
CREST OF THE SOUTHERN SIERRA NEVADA. WITH PROGS INDICATING A LIMITED
AMOUNT OF CAPE AND INSTABILITY NEAR THE CREST THROUGH EARLY THIS
EVENING...WILL LEAVE MENTION OF A SLIGHT CHANCE OF SHOWERS FOR THE
THE SOUTHERN SIERRA CREST.

12Z WRF/GFS ARE INDICATING A SLIGHT STRENGTHENING OF THE RIDGE
THROUGH FRIDAY AS 850 MB TEMPS ARE PROGGED TO RISE BY 1 DEG C ON
BOTH THURSDAY AND FRIDAY WHICH MIGHT BE OFFSET BY SOME LOW LEVEL
MARINE COOLED AIR SPILLING IN THROUGH THE DELTA INTO THE SAN
JOAQUIN VALLEY. AS A RESULT...MINIMUM TEMPERATURES ACROSS THE SAN
JOAQUIN VALLEY AND SOUTHERN SIERRA FOOTHILLS WILL CONTINUE TO
FLIRT WITH THE CENTURY MARK WHILE TRIPLE DIGIT HEAT WILL CONTINUE
TO BE THE RULE ACROSS THE KERN COUNTY DESERTS. RH PROGS ARE
INDICATING SOME HIGH LEVEL MOISTURE POSSIBLY STREAMING IN FROM THE
SOUTH FRIDAY NIGHT AND SATURDAY. HOWEVER...THE MID LEVELS ARE
EXPECTED TO REMAIN VERY DRY SO NO CONVECTION IS ANTICIPATED FOR
THURSDAY AND FRIDAY. BY SATURDAY...THE UPPER RIDGE IS PROGGED TO
BEGIN TO FLATTEN AS VORT ENERGY STREAMS INTO THE PAC NW. THIS
WILL TURN THE UPPER FLOW TO THE SOUTHWEST AND KEEP ANY TROPICAL
MOISTURE WELL TO THE EAST OF OUR AREA. THE MEDIUM RANGE PROGS
INDICATES THE RIDGE WILL SLOWLY WEAKEN DURING THE FIRST HALF OF
NEXT WEEK WHILE A TROUGH DIGS OVER THE WESTERN CONUS. THE GFS IS
MORE AGGRESSIVE AT BREAKING DOWN THE RIDGE THEN THE ECMWF IS IS
INDICATES A MORE PRONOUNCED COOLING TREND THAN THE ECMWF INDICATES
FOR NEXT WEEK. THE ECMWF SHOWS BETTER RUN TO RUN CONSISTENCY
THOUGH SO HAVE DECIDED TO TREND MORE TOWARD THIS SOLUTION SO HAVE
BUMPED UP TEMPERATURES TO NEAR TO SLIGHTLY ABOVE SEASONAL NORMALS
THROUGH THE MEDIUM RANGE PERIOD.

&&

.AVIATION...
VFR CONDITIONS EXPECTED ACROSS THE CENTRAL CA INTERIOR THROUGH 06Z
FRIDAY.

&&

.AIR QUALITY ISSUES...
ON THURSDAY AUGUST 25 2011... UNHEALTHY FOR SENSITIVE GROUPS IN
FRESNO... KERN... KINGS... MADERA... MERCED AND TULARE COUNTIES.
FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG

&&

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

PUBLIC...DURFEE
PREVIOUS DISCUSSION...DS
AVN/FW...JEB
SYNOPSIS...BSO

WEATHER.GOV/HANFORD