031 
 WTPZ42 KNHC 122025
 TCDEP2
 TROPICAL STORM ISIS DISCUSSION NUMBER  19
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 2 PM PDT SUN SEP 12 2004
  
 ISIS IS SHOWING SIGNS OF WEAKENING. VISIBLE ANIMATION DEPICTS A
 POORLY DEFINED PARTIALLY EXPOSED LOW-LEVEL CENTER. OUTFLOW
 BOUNDARIES APPEAR MORE ABUNDANT THAN LOW CLOUD LINES ASSOCIATED
 WITH THE CENTER. IMAGERY ALSO REVEALS WIDESPREAD STRATOCUMULUS
 FORCING IN FROM THE NORTH AND NORTHWEST. WHICH LEADS US TO BELIEVE
 THAT THIS MAY BE RESTRICTING THE MOISTURE CONTENT IN THE LOW/MID
 LEVELS. WATER VAPOR ANIMATION INDICATES THAT THE EASTERLY SHEAR
 PERSISTS. SATELLITE CURRENT INTENSITY ESTIMATES FROM ALL AGENCIES
 REMAIN AT 45 KT. THE INITIAL INTENSITY REMAINS AT 45 KT JUST IN
 CASE THE CENTER HAS MOVED OR REDEVELOPED FURTHER BENEATH THE
 CONVECTION. IF THIS IS NOT THE CASE AND THE CURRENTLY UNFAVORABLE
 ENVIRONMENT CONTINUES...THE INTENSITY WILL HAVE TO BE DECREASED ON
 THE NEXT ADVISORY. THE SHIPS MODELS HAS CONSISTENTLY BEEN TOO LOW
 ON THE STRENGTH OF THE EASTERLY SHEAR. 10 TO 20 KT UPPER EASTERLIES
 REMAIN OVER THE TROPICAL CYCLONE ACCORDING TO THE CIMSS SHEAR
 ANALYSIS. THE INTENSITY FORECAST REMAINS UNCHANGED FOR NOW.
 HOWEVER...THE SLOW INTENSIFICATION TREND TO 55 KT IN 48 HOURS MAY
 BE TOO GENEROUS GIVEN THE CURRENT STATE OF THE ENVIRONMENT. 
 
 THE INITIAL MOTION IS WESTWARD OR 270/8...WHICH IS SLIGHTLY SLOWER
 THAN THE PREVIOUS ADVISORY. THE FORECAST TRACK IS BASICALLY AN
 UPDATE OF THE PREVIOUS FORECAST...AND AGREES WITH THE MODEL
 CONSENSUS.
  
 FORECASTER ROBERTS/BEVEN
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      12/2100Z 17.4N 124.1W    45 KT
  12HR VT     13/0600Z 17.4N 125.4W    45 KT
  24HR VT     13/1800Z 17.4N 127.5W    50 KT
  36HR VT     14/0600Z 17.4N 129.5W    50 KT
  48HR VT     14/1800Z 17.4N 131.0W    55 KT
  72HR VT     15/1800Z 17.4N 133.0W    55 KT
  96HR VT     16/1800Z 17.4N 134.0W    55 KT
 120HR VT     17/1800Z 17.4N 134.5W    55 KT
  
  
 $$