Flood in California, April 24, 2002

EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 AM PDT WED APR 24 2002

.SYNOPSIS...MID AND HIGH CLOUDS MOVING UP FROM THE SOUTH WILL BRING
A FEW LIGHT SHOWERS TO SOUTHWEST CALIFORNIA TODAY. A COOL LOW
PRESSURE SYSTEM TO THE WEST OF THE SOUTHERN CALIFORNIA COAST WILL
MOVE INLAND LATE THURDAY NIGHT AND FRIDAY BRINGING SHOWERS AND A
CHANCE OF THUNDERSTORMS TO THE AREA. A WEAK RIDGE WILL FOLLOW THIS
LOW FRIDAY NIGHT INTO SATURDAY BUT ANOTHER UPPER LOW WILL MOVE INTO
THE AREA LATE SUNDAY AND MONDAY.

.DISCUSSION...ALREADY UPDATED THE ZONE FORECAST TO PUT ISOLATED
SHOWERS AND 20 PERCENT POPS FOR ALL AREAS FOR TODAY AND TO SCALE
BACK MAXIMUM TEMPERATURES FOR TODAY BECAUSE OF THE THICK CLOUD
COVER. NO FURTHER UPDATES ARE PLANNED.

KSOX AND KNKX 88DS ARE SHOWING A SIGNIFICANT AREA OF PRECIPITATION
TO THE SOUTH AND SOUTHWEST OF SOUTHERN CALIFORNIA MOVING NORTH INTO
THE AREA. SOME RETURNS AS HIGH AS 45 TO 50 DBZS ARE SHOWING UP ON
THE KNKX 88D. THE AREA JUST SOUTH OF SAN DIEGO COUNTY IS MOVING
NORTH ABOUT 30 KNOTS WHILE THE AREA FURTHER OFFSHORE IS MOVING NORTH
ABOUT 45 KNOTS AND THIS IS SUPPORTED BY THE VWP FROM BOTH 88DS.
EXCEPT FOR THE BOUNDRY LAYER...THE LOWER LEVELS ARE STILL FAIRLY DRY
SO EXPECT MOST OF THE PRECIPITATION TO NOT REACH THE GROUND BUT SOME
AREAS MIGHT ACTUALLY RECEIVE MEASURABLE AMOUNTS.

12Z ETA IS A LITTLE SLOWER THAN THE 06Z AVN WITH THE CUTOFF LOW
MOVING THROUGH LATE THURSDAY NIGHT AND FRIDAY BUT ONLY BY ABOUT 6
HOURS. THE 06Z AVN SHOWED A FAIRLY SIGNIFICANT AREA OF HIGH RH
MOVING THROUGH BETWEEN 06Z AND 12Z FRIDAY WITH LIFTED INDECIES NEAR
ZERO. THE 12Z ETA IS NOT QUITE AS LOW WITH THE LIFTED INDEX BUT IT
STILL SHOWS ENOUGH INSTABILITY TO SUPPORT AT LEAST ISOLATED
THUNDERSTORMS LATE THURSDAY INTO FRIDAY MORNING.

MEDIUM RANGE MODELS ARE IN CLOSE AGREEMENT THROUGH THE EXTENDED
PERIOD BRINGING ANOTHER UPPER LOW SOUTH ON SUNDAY TO OFF THE CENTRAL
CALIFORNIA COAST THEN SWINGING THIS LOW INLAND ACROSS SOUTHERN
CALIFORNIA DURING THE LATTER PART OF NEXT WEEK. THIS LOW DOES NOT
DEVELOP AS FAR OFFSHORE AS THE CURRENT LOW SO DO NOT EXPECT MUCH
RIDGING AHEAD OF THIS LOW OVER SOUTHERN CALIFORNIA. IT APPEARS MOST
OF NEXT WEEK WILL BE COOL AND UNSETTLED.

.SAN...NONE.

HORTON