Wildfire in California, August 22 to 26, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
915 AM PDT WED AUG 22 2007

.UPDATE...
THE COASTAL MARINE LAYER HAS DEEPENED TO AROUND 2300 FEET AT FORT
ORD THIS MORNING. HOWEVER...SURFACE-PRESSURE GRADIENTS ARE LESS THAN
1 MB STRONGER THAN 24 HOURS EARLIER...AND WINDS AT TRAVIS AFB ARE
ONLY 13 KTS FROM THE SOUTHWEST...SO DO NOT EXPECT ANY SIGNIFICANT
MARINE AIR PUSH INTO THE SAN JOAQUIN VALLEY BEFORE LATE AFTERNOON AT
THE EARLIEST.

THIS MORNING/S LOW-LEVEL SOUNDING FOR FRESNO IS IN AGREEMENT WITH
THE FORECASTED HIGH OF 101...SO DO NOT SEE ANY NEED TO CHANGE THE
FORECAST AT THIS TIME.

THE LONG-TERM CONCERN CONTINUES TO BE THE TROPICAL MOISTURE FROM
HURRICANE DEAN. THE LAST FEW MEDIUM-RANGE MODEL RUNS HAVE BACKED OFF
ON THE STRENGTH OF THE UPPER-LEVEL SHORT-WAVE FORECAST TO MOVE
THROUGH THE PACIFIC NORTHWEST SUNDAY. THIS WOULD ALLOW THE UPPER-
LEVEL RIDGE OVER THE SOUTHEASTERN U.S. TO BUILD BACK INTO CALIFORNIA
WITH MOISTURE WRAPPING AROUND THE RIDGE INTO THE MOUNTAINS AND
DESERTS OF THE HANFORD WARNING/FORECAST AREA. SLIGHT CHANCE POPS FOR
SUNDAY NIGHT THROUGH MONDAY NIGHT OVER THE MOUNTAINS AND DESERTS
CONTINUE TO LOOK GOOD...AND THE 00Z GFS EXTENDED MEX GUIDANCE FOR
EDWARDS AFB AND CHINA LAKE ALSO IS IN AGREEMENT WITH 15-20 PERCENT
POPS DURING THAT PERIOD /WITH THE GFS BRINGING 15 PERCENT POPS INTO
EDWARDS AFB DURING THE DAY SUNDAY/.

&&

.DISCUSSION...
STRONG HIGH PRESSURE ALOFT OVER THE FORECAST AREA IS WEAKENING IN
RESPONSE TO A PACIFIC TROUGH DIGGING SOUTH OVER THE GREAT BASIN.
EVEN WITH LOWERING H5 HEIGHTS OF 3-4 DM...FORECAST CHARTS INDICATE
LITTLE CHANGE IN 1000-500 MB THICKNESS VALUES FOR THIS AFTERNOON.
MAX TEMPS THIS AFTERNOON LIKELY TO REMAIN ABOUT THE SAME AS
YESTERDAY. AS THE TROUGH DIGS FARTHER SOUTH AND BECOMES A LITTLE
DEEPER ON THU OVER THE WESTERN STATES... SLIGHTLY LOWER
HEIGHTS/THICKNESS WILL RESULT IN A FEW DEGREES COOLING FOR THE CWA
THU AND FRI. THE AIRMASS WILL REMAIN DRY IN THE PREDOMINATE
NORTHWEST FLOW ALOFT WITH GENERALLY CLEAR SKIES CONTINUING OVER
THE AREA INTO THE WEEKEND.

THE WEAK TROUGH OVER THE WESTERN STATES WILL SHIFT EAST LATE FRIDAY
WITH HIGHER PRESSURE REBUILDING OVER THE WEEKEND. CONTINUED DRY
SAT AND SUN WITH MOSTLY CLEAR SKIES. GFS STILL SHOWING WEAK
SOUTHERLY FLOW NEXT MON WITH MOISTURE FROM HURRICANE DEAN REACHING
SOUTHERN CALIF AS EARLY AS SUN MORNING. BOTH GFS AND ECMWF SHOW
ENOUGH SOUTHERLY COMPONENT IN THE UPPER WINDS TO POSSIBLY SPREAD
MOISTURE AND THE SLIGHT CHANCE OF PRECIP NORTH OVER THE KERN
COUNTY MOUNTAINS AND DESERTS AS WELL AS THE SIERRA NEVADA. WILL
KEEP THE THREAT OF PRECIP OVER THESE AREAS...MAINLY ON MON.

&&

.AVIATION...LOOK FOR VFR CONDITIONS ACROSS THE CENTRAL CA INTERIOR
THROUGH 18Z THURSDAY AS THE FLOW ALOFT BECOMES MORE NORTHWESTERLY.

FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT
AND KBFL...AND TWEB ROUTES 421 AND 423.

&&

.AIR QUALITY ISSUES...
NONE.

&&

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

&&

UPDATE...SANGER/DCH
PREVIOUS...GREISS/MOLINA

WEATHER.GOV/HANFORD