FNUS76 KSTO 131703
FWSSTO

SPOT FORECAST FOR SAN DIMAS ENGINE BURN OVER STUDY
NATIONAL WEATHER SERVICE SACRAMENTO CA
1003 AM PDT TUE SEP 13 2011

IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE NATIONAL WEATHER SERVICE.

.DISCUSSION...
UPPER LEVEL LOW PRESSURE SITTING OVER CENTRAL CA AND NV WILL WEAKEN
SLIGHTLY TODAY. THIS WILL STILL CAUSE SOME INSTABILITY NEAR THE
REGION. THE BEST INSTABILITY WILL BE IN THE FOOTHILLS AND MOUNTAINS
TO THE EAST OF THE BURNSITE WITH A SLIGHT CHANCE OF THUNDERSTORMS.
MODEL SOUNDINGS SHOW WEAK INSTABILITY NEAR THE BURNSITE THIS
AFTERNOON WITH LIFTED INDEX VALUES NEAR -1...BUT THE INSTABILITY IS
ELEVATED NEAR 10,000 FT ABOVE GROUND LEVEL AND HIGHER. VERTICAL WIND
PROFILE INDICATES LIGHT WINDS UP TO AROUND 15,000 FT SO INSTABILITY
MAY NOT MIX DOWN TO THE SURFACE OF THE BURNSITE. SURFACE WINDS NEAR
THE BURNSITE WILL BE LIGHT TO MODERATE.

THE LOW PRESSURE IS FORECAST TO WEAKEN AND MOVE EASTWARD BETWEEN
NEVADA AND THE FOUR CORNERS AREA BY THURSDAY. THUS...THE AIR MASS
WILL BE MORE STABLE WITH WEAKER WINDS ALOFT AND AT THE SURFACE.
CURRENT FORECAST HAS NO THUNDERSTORMS ON THURSDAY FOR NORTHERN
INTERIOR CALIFORNIA INCLUDING THE TERRAIN TO THE EAST OF THE
BURNSITE.


.TODAY...

SKY/WEATHER.........MOSTLY SUNNY OVER BURNSITE. SLIGHT CHANCE OF
                    THUNDERSTORMS DURING THE DAY IN THE UPPER
                    FOOTHILLS TO THE EAST OF THE BURNSITE.
MAX TEMPERATURE.....91-96.
MIN HUMIDITY........23-28 PERCENT.
WIND (20 FT)........
   SLOPE/VALLEY.....LIGHT WINDS BECOMING WEST 5 TO 10 MPH IN THE
                    AFTERNOON.
   RIDGETOP.........LIGHT WINDS.
MIXING HEIGHT.......500-1500 FT AGL INCREASING TO 5000-6000 FT AGL.
MIXING WINDS........SOUTHWEST TO WEST AROUND 5 MPH.

.THURSDAY THE 15TH...

SKY/WEATHER.........MOSTLY CLEAR.
MAX TEMPERATURE.....86-90.
MIN HUMIDITY........24-30 PERCENT.
WIND (20 FT)........
   SLOPE/VALLEY.....SOUTHWEST 1 TO 6 MPH.
   RIDGETOP.........LIGHT WINDS.
MIXING HEIGHT.......INCREASING TO 4000-5000 FT AGL
                    EARLY IN THE AFTERNOON.
MIXING WINDS........LIGHT WINDS.


FORECASTER...JBB
REQUESTED BY...BILL BAXTER
REASON FOR REQUEST...PRESCRIBED

$$

REQUESTED BY...BILL BAXTER
REASON FOR REQUEST...STATE, TRIBAL OR LOCAL FIRE AGENCY WORKING IN COORDINATION WITH A
FEDERAL PARTICIPANT IN THE INTERAGENCY AGREEMENT FOR METEOROLOGICAL SERVICES.