000
WTPZ43 KNHC 020834
TCDEP3
TROPICAL STORM OLAF DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP182009
200 AM PDT FRI OCT 02 2009
 
SATELLITE IMAGES SHOW A LARGE AREA OF DEEP CONVECTION CONFINED TO
THE NORTHERN SEMICIRCLE OF THE CIRCULATION. THIS ASYMMETRIC
STRUCTURE IS LIKELY DUE TO 10-15 KT OF SOUTHERLY VERTICAL WIND
SHEAR...ACCORDING TO ANALYSES FROM CIMSS AT THE UNIVERSITY OF
WISCONSIN. SATELLITE INTENSITY ESTIMATES ARE 35 KT AND 45 KT FROM
TAFB AND SAB...RESPECTIVELY. THE INITIAL INTENSITY IS RAISED TO
40 KT IN AGREEMENT WITH THESE ESTIMATES AND A 0142 UTC QUIKSCAT
PASS.
 
OLAF HAS ONLY A SMALL WINDOW TO STRENGTHEN FURTHER. A LARGE-SCALE
DEEP-LAYER TROUGH EXTENDING SOUTHWESTWARD FROM CALIFORNIA WILL
INDUCE STRONG SOUTHWESTERLY SHEAR OVER OLAF WITHIN THE NEXT DAY OR
SO. THIS...COMBINED WITH GRADUALLY COOLING SSTS SHOULD CAUSE
WEAKENING TO A REMNANT LOW BY 48 HOURS. THIS INTENSITY FORECAST IS
IN GOOD AGREEMENT WITH DYNAMICAL AND STATISTICAL GUIDANCE AND IS AN
UPDATE OF THE PREVIOUS ONE.
 
A SERIES OF MICROWAVE PASSES HAVE HELPED LOCATE THE CENTER AND THE
INITIAL MOTION ESTIMATE IS 360/10...SLIGHTLY FASTER AND TO THE
RIGHT OF THE PREVIOUS ESTIMATE. OLAF IS LOCATED AT THE WESTERN
PERIPHERY OF A MID-LEVEL RIDGE CENTERED OVER MEXICO AND THIS
SHOULD BE THE PRIMARY STEERING FEATURE OVER THE NEXT 12-24 HOURS.
THEREAFTER...THE DEEP-LAYER TROUGH TO THE NORTHWEST IS EXPECTED TO
SHIFT EASTWARD CAUSING A NORTHEASTWARD MOTION TO COMMENCE. THIS
TRACK FORECAST HAS SHIFTED TO THE RIGHT AND IS FASTER THAN THE
PREVIOUS FORECAST TO ACCOUNT FOR THE INITIAL MOTION AND TO COME IN
BETTER AGREEMENT WITH THE MODEL GUIDANCE.
 
THE 34-KT WIND RADII HAVE BEEN ADJUSTED OUTWARD OVER THE EASTERN
SEMICIRCLE BASED ON A 0142 UTC QUIKSCAT PASS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/0900Z 22.0N 117.5W    40 KT
 12HR VT     02/1800Z 23.0N 117.7W    40 KT
 24HR VT     03/0600Z 24.3N 117.6W    35 KT
 36HR VT     03/1800Z 25.3N 116.7W    30 KT
 48HR VT     04/0600Z 26.2N 115.5W    25 KT...REMNANT LOW
 72HR VT     05/0600Z 27.5N 113.0W    20 KT...REMNANT LOW
 96HR VT     06/0600Z...DISSIPATED
 
$$
FORECASTER CANGIALOSI/BEVEN