000
WTPZ44 KNHC 230832
TCDEP4
 
TROPICAL STORM DORA DISCUSSION NUMBER  20
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042011
200 AM PDT SAT JUL 23 2011
 
CONVECTION HAS RAPIDLY DETERIORATED DURING THE PAST 6 HOURS DUE TO
NORTHERLY SHEAR AND COOLER SEA-SURFACE TEMPERATURES BENEATH THE
CYCLONE. AN ASCAT OVERPASS AT 0516Z ALSO INDICATED THAT 34-KT WINDS
HAVE RETRACTED CLOSER TO THE CENTER OF DORA IN THE WESTERN
SEMICIRCLE. THE INITIAL INTENSITY IS BASED ON SATELLITE CURRENT
INTENSITY ESTIMATES OF 45 FROM BOTH TAFB AND SAB.

THE INITIAL MOTION ESTIMATE IS 310/8...AND LEANS HEAVILY TOWARD
MICROWAVE SATELLITE POSITION ESTIMATES. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST REASONING. DORA SHOULD CONTINUE TO
WEAKEN AND BECOME MORE VERTICALLY SHALLOW...AND BE STEERED
NORTHWESTWARD AROUND THE SOUTHWESTERN PERIPHERY OF A LARGE LOW- TO
MID-LEVEL SUBTROPICAL RIDGE SITUATED OVER MUCH OF THE SOUTHERN U.S.
AND NORTHERN MEXICO. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE
PREVIOUS ADVISORY AND IS CLOSE TO THE DYNAMICAL MODEL CONSENSUS.

THE RECENT RAPID DEMISE OF CONVECTION ANYWHERE WITHIN THE
CIRCULATION SUGGESTS THAT DORA IS NOT LONG FOR THIS WORLD. MODERATE
TO STRONG NORTHERLY SHEAR AND STABLE AIR TO THE NORTH AND WEST OF
THE CYCLONE WILL CONTINUE TO TAKES IT TOLL ON THE CYCLONE. THE
CONTINUED NORTHWESTWARD MOTION WILL ALSO RESULT IN DORA MOVING OVER
COOLER OCEAN TEMPERATURES OF LESS THAN 23C...WHICH WILL FURTHER ACT
TO ENHANCE THE WEAKENING PROCESS. AS A RESULT...DORA IS EXPECTED TO
BECOME A DEPRESSION WITHIN THE NEXT 12-18 HOURS AND DEGENERATE INTO
A NON-CONVECTIVE REMNANT LOW PRESSURE SYSTEM BY 24 HOURS...IF NOT
SOONER. 

GIVEN THE RECENT AND EXPECTED RAPID WEAKENING OF DORA...THE TROPICAL
STORM WARNING FOR SOUTHERN BAJA CALIFORNIA COULD BE DISCONTINUED
LATER THIS MORNING.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/0900Z 20.9N 111.2W   45 KT  50 MPH
 12H  23/1800Z 21.6N 112.0W   35 KT  40 MPH
 24H  24/0600Z 22.7N 113.2W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  24/1800Z 23.8N 114.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  25/0600Z 24.8N 115.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  26/0600Z 26.2N 117.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  27/0600Z...DISSIPATED
 
$$
FORECASTER STEWART