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TROPICAL DEPRESSION OLIVIA DISCUSSION NUMBER  30
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT MON OCT 09 2000
 
SOME MODERATE CONVECTION HAS REDEVELOPED NEAR THE CENTER IN A LONG
CURVED BAND ON THE SOUTH SIDE.  OTHER SMALL CONVECTIVE ELEMENTS HAVE
ALSO FILLED IN AROUND THE REST OF THE CIRCULATION...SO I HAVE OPTED
TO MAINTAIN THE INTENSITY AT 30 KT IN CASE THE CONVECTION DECIDES TO
COME BACK LATER THIS EVENING.
 
THE INITIAL MOTION IS 315/6.  THE FORWARD SPEED OF OLIVIA HAS
DECREASED DURING THE PAST 6 HOURS.  THIS MAY BE DUE TO THE LACK OF
DEEP CONVECTION TO MAINTAIN A DEEP VERTICAL CIRCULATION.  AS
MENTIONED IN THE PREVIOUS ADVISORY...THE STRONG SURFACE HIGH
PRESSURE TO THE RIDGE TO THE NORTHWEST AND NORTH SHOULD IMPEDE ANY
SIGNIFICANT NORTHWESTWARD MOTION.  THE KEY TO THE FORECAST REMAINS
WHETHER OR NOT OLIVIA DEVELOPS ANY MORE DEEP CONVECTION NEAR THE
CENTER...WHICH WOULD CAUSE THE SYSTEM TO BE STEERED NORTH AND THEN
NORTHEAST BY THE DEEP LAYER FLOW THAT THE GLOBAL MODELS ARE
FORECASTING.  THE OFFICIAL FORECAST MAINTAINS THE EARLIER
RECURVATURE SCENARIO...WHICH IS SIMILAR TO THE MAJORITY OF THE MODEL
GUIDANCE.  HOWEVER...IF DEEP CONVECTION DOES NOT REDEVELOP IN THE
NEXT 12 HOURS...THEN OLIVIA WILL TAKE SLOW NORTHWEST TRACK AND
QUICKLY DISSIPATE.
 
THERE IS NO CHANGE TO THE PREVIOUS INTENSITY FORECAST REASONING. 
OLIVIA HAS BEEN TRYING TO DEVELOP NEW CONVECTION NEAR THE CENTER THE
PAST 4 TO 6 HOURS.  IF THIS TREND PERSISTS...THEN OLIVIA COULD
REMAIN A TROPICAL DEPRESSION THROUGH THE FORECAST PERIOD...AND
POSSIBLY BEYOND THAT.  HOWEVER...IF THE CURRENT MODERATE CONVECTION
WEAKENS...THEN OLIVIA WILL LIKELY DISSIPATE IN 24 HOURS.
 
NOTE...12 FT SEAS RADII HAVE BEEN ADDED TO THE FORECAST ADVISORY.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     09/2100Z 20.6N 118.2W    30 KTS
12HR VT     10/0600Z 21.6N 118.4W    25 KTS
24HR VT     10/1800Z 23.3N 117.8W    25 KTS
36HR VT     11/0600Z 24.9N 116.1W    20 KTS...DISSIPATING
48HR VT     11/1800Z 26.0N 113.5W    20 KTS...DISSIPATING
72HR VT...DISSIPATED
 
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