000
WTPZ43 KNHC 120833
TCDEP3
 
TROPICAL STORM HECTOR DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP082012
200 AM PDT SUN AUG 12 2012

THE CLOUD PATTERN OF THE STORM IS DOMINATED BY A MASS OF COLD-TOPPED
CONVECTION NEAR AND TO THE WEST OF THE ESTIMATED CENTER...AND
CONVECTIVE BANDING FEATURES HAVE BECOME ILL-DEFINED.  USING A BLEND
OF DVORAK ESTIMATES FROM TAFB AND SAB...THE CURRENT INTENSITY IS
SET AT 40 KT.  THE RATHER SHARP EASTERN EDGE OF THE CONVECTIVE MASS
IS HIGHLY SUGGESTIVE OF EASTERLY SHEAR...AND IN FACT THE SHIPS
MODEL DIAGNOSES THE VERTICAL SHEAR TO BE ON THE ORDER OF 20 KT FOR
THE NEXT DAY OR SO.  IN 36 TO 48 HOURS THE GLOBAL MODELS SHOW THE
UPPER-LEVEL ANTICYCLONE NORTH OF HECTOR WEAKENING...RESULTING IN A
REDUCTION OF THE EASTERLY SHEAR.  THIS WOULD ALLOW FOR SOME
STRENGTHENING UNTIL ABOUT 72 HOURS.  AFTER THAT TIME... HOWEVER...
HECTOR SHOULD BE MOVING OVER PROGRESSIVELY COOLER WATERS WHICH
SHOULD LEAD TO WEAKENING.  THE OFFICIAL INTENSITY FORECAST IS
SIMILAR TO THE PREVIOUS ONE AND REMAINS A LITTLE HIGHER THAN MOST OF
THE GUIDANCE.

WITH INFRARED IMAGERY...IT IS DIFFICULT TO LOCATE THE CENTER VERY
PRECISELY...AND THE INITIAL MOTION IS A RATHER UNCERTAIN 285/10. 
MUCH OF THE DYNAMICAL GUIDANCE SHOWS A SLOWING OF THE FORWARD SPEED
AND A TURN TOWARD THE LEFT AS HECTOR APPEARS TO BE INTERACTING WITH
A BROADER CYCLONIC GYRE OR A TROUGH TO THE SOUTH.  LATER IN THE
FORECAST PERIOD THIS INFLUENCE IS EXPECTED TO LESSEN...AND THE
MOTION SHOULD TURN BACK TOWARD THE WEST-NORTHWEST OR NORTHWEST AS
THE CYCLONE BECOMES STEERED BY THE FLOW TO THE SOUTHWEST OF A
MID-TROPOSPHERIC HIGH NEAR THE SOUTHWESTERN UNITED STATES.  THE
OFFICIAL TRACK FORECAST IS NOT MUCH DIFFERENT FROM THE PREVIOUS ONE
AND ROUGHLY BETWEEN THE LATEST GFS AND ECMWF TRACKS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  12/0900Z 18.6N 109.4W   40 KT  45 MPH
 12H  12/1800Z 18.7N 110.5W   40 KT  45 MPH
 24H  13/0600Z 18.5N 111.3W   45 KT  50 MPH
 36H  13/1800Z 18.4N 111.8W   45 KT  50 MPH
 48H  14/0600Z 18.5N 112.4W   50 KT  60 MPH
 72H  15/0600Z 19.4N 114.4W   55 KT  65 MPH
 96H  16/0600Z 20.5N 116.0W   50 KT  60 MPH
120H  17/0600Z 21.5N 118.5W   40 KT  45 MPH
 
$$
FORECASTER PASCH