605 
 WTPZ43 KNHC 270232
 TCDEP3
  
 TROPICAL STORM MIRIAM DISCUSSION NUMBER  21
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132012
 800 PM PDT WED SEP 26 2012
  
 CONVECTIVE CLOUD TOPS CONTINUE TO WARM...AND DEEP CONVECTION IS
 LIMITED TO A BAND LOCATED ABOUT 150 N MI TO THE NORTH OF THE
 CENTER.  DVORAK NUMBERS HAVE DROPPED TO T3.0/4.0 FROM TAFB AND
 T2.0/3.0 FROM SAB.  BASED ON A BLEND OF THE FINAL-T AND CI
 NUMBERS...THE ADVISORY INTENSITY IS SET AT 40 KT.  THIS IS
 SUPPORTED BY A CI NUMBER OF 2.8 FROM THE LATEST UW-CIMSS ADT
 ESTIMATE.
 
 MIRIAM WILL CONTINUE TO BE AFFECTED BY 20-25 KT OF DEEP-LAYER
 WEST-SOUTHWESTERLY SHEAR IN THE COMING DAYS...AND THE CENTER IS
 BEGINNING TO MOVE OVER WATER THAT IS COLDER THAN 26C.  THIS
 ENVIRONMENT IS NOT LIKELY TO SUPPORT SIGNIFICANT DEEP CONVECTION...
 AND MIRIAM COULD BECOME POST-TROPICAL AS EARLY AS THURSDAY IF
 CURRENT CONVECTIVE TRENDS HOLD.  THE NHC INTENSITY FORECAST FOLLOWS
 THE SAME WEAKENING SHOWN BY THE STATISTICAL GUIDANCE...AND MOST OF
 THE GLOBAL MODELS DISSIPATE THE REMNANT LOW IN ABOUT 5 DAYS.
 
 MIRIAM IS MOVING NORTH-NORTHWESTWARD AT ABOUT 6 KT AS IT ROTATES
 AROUND A MID-TROPOSPHERIC LOW LOCATED NOT TOO FAR TO ITS WEST.  THE
 CYCLONE WILL SOON BE RUNNING INTO A LARGE AREA OF HIGH PRESSURE
 CENTERED TO THE WEST OF CALIFORNIA...AND IT IS LIKELY TO BEGIN
 MOVING SLOWLY WESTWARD OR EVEN SOUTHWESTWARD AFTER 48 HOURS. 
 ALMOST ALL THE TRACK MODELS SHOW THE HIGH PRESSURE PUSHING MIRIAM
 SOUTHWARD BEFORE IT DISSIPATES...AND THAT SCENARIO IS INDICATED IN
 THE OFFICIAL FORECAST.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  27/0300Z 21.5N 115.7W   40 KT  45 MPH
  12H  27/1200Z 22.2N 116.1W   35 KT  40 MPH
  24H  28/0000Z 22.7N 116.6W   30 KT  35 MPH
  36H  28/1200Z 22.8N 117.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
  48H  29/0000Z 22.9N 117.3W   20 KT  25 MPH...POST-TROP/REMNT LOW
  72H  30/0000Z 22.9N 117.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
  96H  01/0000Z 22.5N 118.0W   15 KT  15 MPH...POST-TROP/REMNT LOW
 120H  02/0000Z...DISSIPATED
  
 $$
 FORECASTER BERG