EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 300 AM PDT TUE SEP 14 1999
...SYNOPSIS...
A WEAK UPPER LOW OVER NORTHERN AND CENTRAL CALIFORNIA WILL BRING
WEAK ONSHORE FLOW TO SOUTHERN CALIFORNIA THE NEXT FEW DAYS WITH
SEASONAL INLAND TEMPERATURES AND SLIGHTLY BELOW NORMAL COASTAL
TEMPERATURES. SLOW DRYING OF MONSOONAL MOISTURE WILL CONTINUE IN THE
MOUNTAINS AND DESERTS WITH FEWER AFTERNOON CLOUDS AND WITH
THUNDERSTORMS MOVING EAST OF SOUTHERN CALIFORNIA AFTER TODAY.
COASTAL AREAS WILL SEE A GRADUAL INCREASE IN NIGHT AND MORNING LOW
CLOUDS.
...DISCUSSION...
SHORT RANGE MDLS ARE IN AGREEMENT IN FORECASTING A DEAMPLIFICATION
OF THE PATTERN OVR WRN NOAM DURG THE NEXT TWO DAYS...BUT DIFFER IN
THE STRENGTH OF A LINGERING WK UPR TROUGH OVR CA. ONSHR LOW LVL FLOW
FOR SRN CA WL CONTINUE TO BE WK. ETA SHOWS THE LOW AND MID LVL FLOW
ACQUIRING A LTL GREATER WLY COMPONENT OVR SRN CA DURG THE NEXT TWO
DAYS WITH A SLOW DRYING OF THE MID LVL MSTR TODAY AND GREATER DRYING
FOR WED. RUC/MAPS KEEPS MOST CONVECTION THIS AFTERNOON OVR SRN NV
AND THE FAR ERN DESERTS OF SRN CA AS WELL AS THE MTNS OF NRN BAJA
WHILE KPG THUNDERSTORMS OUT OF THE MTNS OF SRN CA. THIS IS
CONSISTENT WITH THE GRADUAL DRYING TREND SHOWN BY THE ETA. WL RETAIN
PARTLY CLOUDY WORDING FOR MTNS/DESERTS FOR THIS AFTERNOON BUT LV OUT
POPS XCP FOR SRNMOST AND ERNMOST MTNS AND DESERTS. WL USE MOSTLY
SUNNY WORDING FOR WED AS ADDITIONAL DRYING OCCURS.
FOR CSTL SXNS...EARLY EVENING ACARS SOUNDINGS/RAOBS SHOWED A MARINE
LYR DEPTH OF AROUND 1000 FT WITH SOME SLOW DEEPENING LIKELY THE NEXT
TWO DAYS AS HEIGHTS ALF SLOWLY LWR. ONSHR FLOW TO REMAIN WK. BOTH
THE RUC AND 12Z COMAPS SHOWED A WK CSTL EDDY DEVELOPING BY MORNING...
THEN DISSIPATING BY AFTERNOON. 00Z COMAPS HAS BACKED OFF ON THE WK
CSTL EDDY FOR THIS MORNING. IN THE PAST...COAMPS HAS BEEN CORRECT IN
TRENDING CORRECTLY WITH REGARD TO EDDY DEVELOPMENT...SO NOW EXPECT
ANY EDDY DEVELOPMENT THIS MORNING TO BE VERY WK IF IT OCCURS AT ALL.
LIKEWISE...COAMPS IS LESS THAN GUNG HO IN FORECASTING AN EDDY FOR
TONIGHT/WED MORNING. WL JUST CONTINUE THE TREND OF A GRADUAL INCR IN
CSTL LOW CLOUDS EACH DAY.
EXTENDED...MED RANGE MDLS ARE FORECASTING A REDEVELOPMENT OF A
BLOCKING PATTERN IN THE VCNTY OF WRN NOAM...THIS TIME SLIGHTLY TO THE
E OF THE CURRENT BLOCK (I.E. OVR BRITISH COLUMBIA AND THE W CST
STATES INSTEAD OF OVR THE ERN PAC JUST OFF THE CST). THIS WOULD
PLACE A WK UPR LOW OVR CA...SUFFICIENT TO KP MONSOONAL MSTR
DISPLACED E OF THE LCL FORECAST AREA...INLAND TEMPERATURES NR
NORMAL...AND CSTL TEMPERATURES SLIGHTLY BLO NORMAL.
SAN 000
.SAN...NONE.
MARTIN