Flood in California, August 8, 2001

EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 AM PDT WED AUG 8 2001

                             ...SYNOPSIS...
MOIST FLOW ALOFT WILL PRODUCE SCATTERED THUNDERSTORMS OVER THE
MOUNTAINS AND DESERTS CONTAINING LOCALLY GUSTY WINDS THIS AFTERNOON.
SOME DRYING DUE TO SOME WEAK WEST FLOW ALOFT SHOULD DECREASE THE
THUNDERSTORM CHANCES SOME ON THURSDAY...THOUGH MORE THUNDERSTORMS
ARE POSSIBLE EARLY NEXT WEEK AS THE FLOW ALOFT BECOMES EASTERLY. A
STRONG MARINE INVERSION WILL BRING EXTENSIVE LOW CLOUDS TO THE
COAST...LINGERING IN THE AFTERNOON IN SOME AREAS.

                            ...DISCUSSION...
THE INVERSION WAS 11 DEG C STRONG THIS MORNING AND A BIT DEEPER THAN
ON TUE...AND WITH LOCAL CLOUDS BEING SOLID OVER THE OCEAN...EXPECT
LOW CLOUDS TO LINGER THIS AFTERNOON AT MOST BEACHES. SLIGHT COOLING
ALOFT THU SHOULD WEAKEN THE INVERSION FOR A BIT MORE CLEARING.

THE NKX SOUNDING THIS MORNING HAD A THIN ERRONEOUS DRY LAYER
IMMEDIATELY ABOVE THE INVERSION...BUT THIS WAS MUCH BETTER THAN THE
SOUNDING FROM TUE. PREC WATER WAS AROUND 1.2 IN WHICH IS NOT ALL
THAT HIGH...BUT VALUES WERE MUCH HIGHER TO THE EAST...INCLUDING
AROUND 1.7 IN AT YUMA. SO...TSTORMS SHOULD BE EXPECTED OVER THE
MTNS...THOUGH AREAL COVERAGE SHOULD NOT BE AS GREAT AS WAS INDICATED
BY THE MIDNIGHT SHIFT...SO POPS WILL BE LOWERED SOMEWHAT. ALSO...THE
FLOW ALOFT WAS MOSTLY SOUTHERLY...WITH THE AREAS OF SOUTHEAST FLOW
AROUND 700 MB BEING MODELED TO SWITCH TO THE SOUTHWEST TODAY...SO
AREAS WEST OF THE MTNS SHOULD NOT SEE TSTORMS. TEMPS ARE SLIGHTLY
COOLER TODAY IN MOST AREAS...SO THE INSTABILITY WILL BE A BIT LESS.
THE EASTERLY WAVE OVER SW TEXAS DOES NOT APPEAR TO BE MOVING WEST AT
THIS TIME...SO WE SHOULD BE FREE OF ANY SORT OF CONVECTION-ENHANCING
DYNAMICS FOR THE NEXT FEW DAYS.

HOWEVER...THE UPPER HIGH IS EXPECTED TO MOVE ALMOST
OVERHEAD...THOUGH IN A SLIGHTLY WEAKENED STATE. THIS HIGH IS NOT
ACCOMPANIED BY ANY OFFSHORE LOW-LEVEL FLOW TRENDS...SO OUR MARINE
LAYER SHOULD CONTINUE AT ABOUT ITS CURRENT DEPTH...MEANING MOSTLY
THE ORANGE AND SAN DIEGO COUNTY COASTS AND SAN DIEGO COUNTY VALLEYS
WILL BE AFFECTED BY NIGHT/MORNING LOW CLOUDS...WITH A FEW COASTAL
AREAS REMAINING CLOUDY IN THE AFTERNOON...ESPECIALLY TODAY. SOME
MOISTURE/INSTABILITY WILL CONTINUE...PROBABLY ENOUGH FOR A SLIGHT
CHANCE OF TSTORMS...AND THIS MAY BE INTRODUCED IN THE AFTERNOON
PACKAGE FOR THU/FRI...DEPENDING PARTLY ON AVN AND THE 18Z MSO.

AN UPDATE TO THE ZONES WILL BE ISSUED SHORTLY.

.SAN...NONE.

MAXWELL