000
WTPZ45 KNHC 080836
TCDEP5
 
TROPICAL STORM OLIVIA DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP152012
200 AM PDT MON OCT 08 2012
 
ASCAT DATA FROM 0552 UTC WAS INCREDIBLY HELPFUL FOR DETERMINING THE
CENTER LOCATION OF OLIVIA AND ADJUSTING THE WIND RADII.  THE ASCAT
AND OTHER MICROWAVE DATA CONFIRM THAT THE LOW-LEVEL CENTER IS
LOCATED NEAR THE SOUTHERN EDGE OF THE DEEP CONVECTION...AND MOST OF
THE TROPICAL-STORM-FORCE WINDS ARE CONFINED TO THE NORTHERN
SEMICIRCLE.  THERE IS A WIDE RANGE IN THE INTENSITY ESTIMATES WITH
THE ASCAT DATA SHOWING MAXIMUM WINDS OF 40-45 KT...AND TAFB AND SAB
ANALYSTS YIELDING 55 KT.  THE LOW BIAS AND RESOLUTION PROPERTIES OF
ASCAT WOULD SUGGEST AN INTENSITY OF ABOUT 50 KT...WHICH WILL REMAIN
THE ESTIMATED STRENGTH OF OLIVIA.

MODERATE SOUTHERLY SHEAR CONTINUES TO AFFECT OLIVIA...AND IT SEEMS
TO HAVE BEEN STRONG ENOUGH TO LIMIT FURTHER INTENSIFICATION.  WHILE
THE WINDOW FOR STRENGTHENING IS CLOSING...THE SHEAR IS NOT EXPECTED
TO INCREASE MUCH DURING THE NEXT 24 HOURS...AND THE INTENSITY OF
OLIVIA SHOULD CHANGE LITTLE DURING THAT TIME.  SOUTHWESTERLY SHEAR
INCREASES SIGNIFICANTLY AFTER 24 HOURS...AND OLIVIA IS FORECAST TO
WEAKEN QUICKLY AS THE LOW- AND MID-LEVEL CIRCULATIONS BECOME
DECOUPLED.  OLIVIA COULD BE A TROPICAL DEPRESSION OR A REMNANT LOW
BY 48 HOURS AND IS LIKELY TO DISSIPATE INTO A TROUGH BY 96 HOURS.

OLIVIA HAS BEEN SLOWING DOWN...AND THE INITIAL MOTION IS 360/4 KT. 
THE STORM IS FORECAST TO CONTINUE THIS MOTION FOR THE NEXT 12 HOURS
OR SO WHILE IT REMAINS ON THE WESTERN SIDE OF A MID-LEVEL
ANTICYCLONE...BUT IT SHOULD BECOME NEARLY STATIONARY BY 24 HOURS AS
THE STEERING CURRENTS COLLAPSE.  ONCE THE SHEAR INCREASES...THE
LOW-LEVEL CENTER WILL TURN TOWARD THE WEST AND WEST-SOUTHWEST UNDER
THE INFLUENCE OF THE TRADE WINDS.  THE PREVIOUS NHC TRACK FORECAST
IS LOCATED ALONG THE NORTHERN EDGE OF THE GUIDANCE ENVELOPE FROM 24
HOURS AND BEYOND...SO THE UPDATED NHC TRACK HAS BEEN NUDGED
SOUTHWARD TO BE CLOSER TO THE BULK OF THE TRACK MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  08/0900Z 16.4N 120.9W   50 KT  60 MPH
 12H  08/1800Z 16.9N 121.0W   50 KT  60 MPH
 24H  09/0600Z 16.9N 121.3W   45 KT  50 MPH
 36H  09/1800Z 16.7N 121.9W   35 KT  40 MPH
 48H  10/0600Z 16.5N 122.6W   30 KT  35 MPH
 72H  11/0600Z 15.5N 124.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  12/0600Z...DISSIPATED
 
$$
FORECASTER BERG