000
WTPZ44 KNHC 210852
TCDEP4
 
HURRICANE DORA DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042011
200 AM PDT THU JUL 21 2011
 
DORA HAS TAKEN ON THE APPEARANCE OF AN ANNUAL HURRICANE DURING THE
LAST SEVERAL HOURS...WITH BANDING FEATURES DIMINISHING AND THE
CLOUD PATTERN NOW MORE SYMMETRIC AROUND THE CIRCULAR EYE.
DVORAK CLASSIFICATIONS AT 0600 UTC SUPPORTED AN INTENSITY OF
115 KT...BUT SINCE THEN CLOUD TOPS AROUND THE EYE HAVE COOLED AND
THE LATEST OBJECTIVE T-NUMBERS FROM UW-CIMSS SUGGEST A SLIGHTLY
HIGHER INITIAL WIND SPEED.  THEREFORE...THE INITIAL INTENSITY IS
SET AT 120 KT FOR THIS ADVISORY.
 
THE HURRICANE HAS TURNED SLIGHTLY TO THE RIGHT DURING THE PAST 6
TO 12 HOURS...AND THE LATEST INITIAL MOTION ESTIMATE IS 305/11.
THIS GENERAL MOTION WITH A REDUCTION IN FORWARD SPEED IS FORECAST
DURING THE NEXT SEVERAL DAYS AS A RIDGE OVER THE CENTRAL UNITED
STATES SLIDES EASTWARD.  THE LATEST TRACK GUIDANCE HAS CHANGED
LITTLE FROM THE PREVIOUS CYCLE FOR THE FIRST 2 TO 3 DAYS...AND THE
OFFICIAL FORECAST IS AN UPDATE OF THE PREVIOUS ONE DURING THAT
PERIOD. BEYOND 3 DAYS...MOST OF THE MODELS HAVE AGAIN SHIFTED
EASTWARD...AND THE NEW NHC TRACK FORECAST HAS BEEN NUDGED IN THAT
DIRECTION.  DORA IS EXPECTED TO MAKE ITS CLOSEST APPROACH TO THE
SOUTHERN BAJA PENINSULA IN ABOUT 48 HOURS.
 
ENVIRONMENTAL CONDITIONS ARE CURRENTLY IDEAL FOR DORA...WITH VERY
LIGHT SHEAR...A MOIST ATMOSPHERE...AND SEA SURFACE TEMPERATURES
NEAR 30C.  THESE CONDITIONS COULD ALLOW DORA TO STRENGTHEN SOME
MORE DURING THE NEXT 12 HOURS OR SO.  THEREAFTER...THE MAJOR
HURRICANE WILL BE MOVING OVER A SHARP SEA SURFACE TEMPERATURE
GRADIENT...CROSSING THE 26C ISOTHERM IN 24-36 HOURS AND THE 22C
ISOTHERM IN 3 TO 4 DAYS.  THEREFORE...RAPID WEAKENING IS FORECAST
TO COMMENCE ON FRIDAY...AND DORA IS NOW EXPECTED TO BECOME A
REMNANT LOW BY DAY 4.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 16.6N 106.1W  120 KT 140 MPH
 12H  21/1800Z 17.5N 107.3W  125 KT 145 MPH
 24H  22/0600Z 18.6N 108.6W  120 KT 140 MPH
 36H  22/1800Z 19.5N 109.8W  100 KT 115 MPH
 48H  23/0600Z 20.3N 111.0W   80 KT  90 MPH
 72H  24/0600Z 21.9N 113.8W   50 KT  60 MPH
 96H  25/0600Z 23.5N 117.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  26/0600Z 25.5N 119.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER CANGIALOSI