000
WTPZ44 KNHC 212047
TCDEP4
 
HURRICANE DORA DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042011
200 PM PDT THU JUL 21 2011
 
WHILE THE EYE OF DORA REMAINS MOSTLY CLEAR...CONVECTION IN THE
EYEWALL HAS WEAKENED SOME DURING THE PAST SEVERAL HOURS.  A BLEND
OF THE INTENSITY ESTIMATES GIVES A LOWER INITIAL WIND SPEED OF 130
KT. THE HURRICANE HAS LIKELY PEAKED AS IT IS CROSSING INTO SLIGHTLY
COOLER WATERS AND THE OUTFLOW PATTERN SUGGESTS THAT NORTHEASTERLY
SHEAR IS AFFECTING THE OUTER PORTION OF THE CIRCULATION.  THE
INTENSITY GUIDANCE IS IN GOOD AGREEMENT ON A GRADUAL DECREASE IN
STRENGTH TONIGHT...AND A RAPID DECLINE BY LATE FRIDAY THROUGH THE
WEEKEND DUE TO AN INCREASE IN NORTHEASTERLY WIND SHEAR AND SSTS
DROPPING BELOW 26C.  THE NHC FORECAST IS BASICALLY AN UPDATE OF THE
PREVIOUS PACKAGE AND IS CLOSE TO THE MODEL CONSENSUS.  THIS SYSTEM
IS LIKELY TO BECOME POST-TROPICAL IN ABOUT 3 DAYS DUE TO IT PASSING
OVER WATERS NEAR 21C.
 
DORA HAS SLOWED DOWN DURING THE PAST SEVERAL HOURS AND IS MOVING
310/8.  THIS GENERAL TRACK IS FORECAST FOR THE NEXT DAY OR SO AS
THE STORM IS STEERED BY A RIDGE OVER MEXICO.  THERE IS SOME
DIVERGENCE OF THE MODELS AFTER THAT TIME WITH SOME OF THE
MODELS...SUCH AS THE GFS...CONTINUING THE NORTHWESTWARD COURSE
WHILE OTHERS...LIKE THE ECMWF...SHOW A GRADUAL TURN TOWARD THE
WEST-NORTHWEST.  A CROSS-SECTION OF THE GFS VERSUS THE ECMWF
INDICATES THE LATTER MODEL HAS A DEEPER VORTEX THAT WOULD RESPOND
MORE TO THE UPPER-LEVEL NORTHEASTERLY FLOW THAT IS FORECAST TO
DEVELOP NEAR DORA IN A DAY OR SO.  THE NHC TRACK WILL STAY ON THE
LEFT SIDE OF THE GUIDANCE ENVELOPE IN DEFERENCE TO THE ECMWF
MODEL...AND IS VERY CLOSE TO THE PREVIOUS FORECAST.
 
A TROPICAL STORM WATCH HAS BEEN ISSUED FOR THE SOUTHERN TIP OF BAJA
CALIFORNIA DUE TO THE FORECAST PROXIMITY OF THE 34 KT WIND RADII
AND THE POSSIBILITY OF THE NHC FORECAST SHIFTING A BIT CLOSER TO
BAJA DURING THE NEXT DAY OR SO.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/2100Z 17.7N 107.4W  130 KT 150 MPH
 12H  22/0600Z 18.5N 108.4W  120 KT 140 MPH
 24H  22/1800Z 19.5N 109.6W  100 KT 115 MPH
 36H  23/0600Z 20.3N 110.7W   80 KT  90 MPH
 48H  23/1800Z 21.2N 112.0W   65 KT  75 MPH
 72H  24/1800Z 23.0N 115.0W   35 KT  40 MPH...POST-TROPICAL
 96H  25/1800Z 24.8N 118.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  26/1800Z 26.5N 120.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER BLAKE