Extreme Fire Weather, Red Flag Warning

FIRE WEATHER PLANNING FORECAST FOR SOUTHWESTERN CALIFORNIA NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 930 AM PDT SUN SEP 26 2010 ...RED FLAG WARNING IN EFFECT UNTIL 9 PM PDT MONDAY DUE TO GUSTY NORTHEAST WINDS AND VERY LOW RELATIVE HUMIDITY FOR THE MOUNTAINS OF VENTURA AND LOS ANGELES COUNTIES...THE VENTURA COUNTY VALLEYS AND THE SANTA CLARITA VALLEY... ...FIRE WEATHER WATCH IN EFFECT FROM THIS EVENING THROUGH MONDAY EVENING FOR THE SAN GABRIEL AND SAN FERNANDO VALLEYS... .DISCUSSION...UPPER LEVEL HIGH PRESSURE WILL CONTINUE TO DOMINATE OVER THE AREA THROUGH TUESDAY...BRINGING VERY HOT AND DRY CONDITIONS TO THE AREA. INLAND LOCALES WILL EXPERIENCE AFTERNOON TEMPERATURES BETWEEN 100 AND 110 DEGREES. AFTERNOON RELATIVE HUMIDITY ACROSS INLAND AREAS WILL FALL INTO THE SINGLE DIGITS AND LOW TEENS FOR EXTENDED PERIODS...WITH VERY POOR OVERNIGHT RECOVERIES. AS FOR WINDS...THE NORTHEAST WINDS ARE WEAKER THIS MORNING DUE TO A WEAKER PRESSURE GRADIENT. HOWEVER THE OFFSHORE GRADIENTS ARE EXPECTED TO INCREASE THIS EVENING AND MONDAY WHICH WILL HELP PRODUCE SOME STRONGER WINDS. THROUGH AND BELOW PASSES AND CANYONS...NORTHEAST WINDS 15 TO 25 MPH ARE EXPECTED WITH SOME HIGHER GUSTS...ESPECIALLY TONIGHT. THROUGH MONDAY...THE COMBINATION OF VERY HOT TEMPERATURES... EXTENDED PERIODS OF LOW RELATIVE HUMIDITY AND SOME GUSTY NORTHEAST WINDS WILL CONTINUE TO PRODUCE CRITICAL FIRE WEATHER CONDITIONS ACROSS THE MOUNTAINS OF VENTURA AND LOS ANGELES COUNTIES...AS WELL AS THE VENTURA COUNTY VALLEYS AND THE SANTA CLARITA VALLEY FROM THIS EVENING THROUGH MONDAY EVENING. THEREFORE...A RED FLAG WARNING REMAINS IN EFFECT FOR THESE AREAS. ACROSS THE SAN FERNANDO AND SAN GABRIEL VALLEYS...CONFIDENCE IS NOT AS HIGH IN REACHING REQUIRED DURATION OF RED FLAG CONDITIONS. THEREFORE...THESE AREAS WILL REMAIN IN A FIRE WEATHER WATCH FROM THIS EVENING THROUGH MONDAY EVENING. VERY WARM TEMPERATURES ARE STILL EXPECTED ON TUESDAY...THEN SOME COOLING IS EXPECTED BY WEDNESDAY AND THURSDAY AS THE UPPER LEVEL RIDGE OF HIGH PRESSURE WEAKENS. AS THE HIGH WEAKENS...SOME MID LEVEL MOISTURE IS EXPECTED TO MOVE INTO THE AREA ON THURSDAY. THIS MOISTURE WILL LIKELY PRODUCE SOME AFTERNOON CUMULUS BUILDUPS OVER THE MOUNTAINS AND DESERTS. AT THIS TIME...NO PRECIPITATION IS FORECAST FOR THURSDAY. HOWEVER...IF THE MOISTURE BECOMES MORE SIGNIFICANT THAN CURRENTLY FORECAST...SOME PRECIPITATION CHANCES MAY BE INTRODUCED. THE SITUATION WILL BE MONITORED CLOSELY.