Wildfire in California, September 9, 2001

EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
212 PM PDT SUN SEP 9 2001

                             ...SYNOPSIS...

THE MARINE LAYER WILL CONTINUE NIGHT AND MORNING LOW CLOUDS AND
LOCAL FOG WEST OF THE MOUNTAINS. OTHERWISE DEVELOPING SOUTHWEST FLOW
ALOFT WILL KEEP THE WEATHER DRY THROUGH TUESDAY. A WEAK TROUGH
PUSHING ONSHORE TO THE NORTH WILL DEEPEN THE MARINE LAYER AGAIN
TUESDAY NIGHT AND WEDNESDAY...FOR MORE EXTENSIVE NIGHT AND MORNING
LOW CLOUDS...ALONG WITH PATCHY DRIZZLE AND FOG. BELOW NORMAL DAYTIME
TEMPERATURES WILL CONTINUE FOR COASTAL AREAS THROUGH THE WEEK.

                            ...DISCUSSION...

THE WANING SEPTEMBER SUN WAS TRUMPED BY THE MARINE LAYER TODAY AS
THE STRATUS REMAINED ENTRENCHED ALONG THE COAST MUCH OF THE DAY
UNDER A 10 DEGREE C INVERSION BASED NEAR 2.9K FT. PATCHY DRIZZLE
DEVELOPED AS WELL WITH ONLY LINDBERGH FIELD MEASURING A TRACE.
DAYTIME TEMPS REMAINED WELL BELOW SEASONAL AVERAGES ALONG THE COAST.

THE 12Z AVN AND ETA MODELS ARE IN GENERAL AGREEMENT...BRINGING THE
WEAK UPPER LOW OFF THE CA COAST INLAND WEDNESDAY AS A BROAD AREA OF
HIGH PRESSURE BUILDS OVER THE SOUTH CENTRAL PART OF THE COUNTRY. AS
THE LOW MOVES INLAND...IT IS REPLACED BY ANOTHER ONE ALONG THE
NORTHERN CA COAST BY FRIDAY.  THE NET RESULT IS INCREASING SW FLOW
ALOFT WITH LITTLE OVERALL CHANGE IN OUR BASIC WEATHER PATTERN. THE
ONLY EXCEPTION IS TUESDAY NIGHT AND WEDNESDAY AS THE UPPER LOW
MOVES ONSHORE TO THE NORTH. THIS SHOULD DEEPEN THE MARINE LAYER
FURTHER...INCREASE THE WINDS IN THE MOUNTAINS AND DESERTS...AND
CAUSE TEMPORARY COOLING INLAND. SOME HIGH LEVEL TROPICAL MOISTURE
MAY GET ENTRAINED IN THE FLOW ABOUT MIDWEEK BUT APPEARS TO BE
INSIGNIFICANT AT THIS TIME AND WILL NOT BE A FACTOR IN THE FORECAST.
MAIN FORECAST PROBLEM WILL BE CLEARING OF THE MARINE LAYER STRATUS
AND MAX TEMP FORECASTS WEST OF THE MOUNTAINS. SINCE THE MODELS ARE
NOT BEEN ABLE TO HANDLE THE MARINE LAYER...IT IS UNLIKELY THAT MOS
OUTPUT WILL COME CLOSE TO REALITY REGARDING MAX TEMPS PARTICULARLY
OVER THE VALLEYS.

LOOKING AHEAD...NO MAJOR CHANGES ARE ADVERTISED BY THE MRF. THE NEXT
UPPER LOW ALONG THE CA COAST IS DRAWN INLAND ABOUT MID NEXT WEEK AND
THE MODEL DOES TRY TO BRING IN SOME SUBTROPICAL MOISTURE OVER SOCAL
BUT WILL HAVE TO WAIT AND SEE IF A FEW MORE RUNS CONFIRM THIS.

JAD