780 
 WTPZ44 KNHC 232035
 TCDEP4
 TROPICAL STORM CELIA DISCUSSION NUMBER  21
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 2 PM PDT FRI JUL 23 2004
  
 A BAND OF DEEP CONVECTION WITH TOPS AS COLD -80C HAS REDEVELOPED
 MORE THAN HALF WAY AROUND THE NORTHWEST SEMICIRCLE DURING THE PAST
 FIVE HOURS. THERFORE...THE INITIAL INTENSITY IS BEING MAINTAINED AT
 35 KT BASED ON A CONSENSUS T2.5...OR 35 KT...CURRENT SATELLITE
 INTENSITY ESTIMATE FROM ALL THREE AGENCIES AND THE IMPROVED BANDING
 STRUCTURE THAT HAS DEVELOPED SINCE THE 18Z INTENSITY ESTIMATES.
  
 THE INITIAL MOTION IS 270/08. WHILE THE TRACK OF CELIA OVER THE PAST
 42 HOURS HAS REMAINED ON THE EXTREME SOUTHERN EDGE OF THE NHC
 MODEL GUIDANCE...THE MAJORITY OF THE MODELS STILL CONTINUE TO MOVE
 CELIA WEST-NORTHWEST OR NORTHWESTWARD INTO THE SUBTROPICAL RIDGE...
 WHICH SEEMS HIGHLY UNLIKELY. AS CELIA MOVES OVER PROGRESSIVELY
 COLDER WATER...THE VERTICAL STRUCTURE SHOULD DECREASE AND THE
 PRIMARY STEERING FLOW SHOULD BE EASTERLY TRADEWIND FLOW ON THE
 SOUTH SIDE OF THE LARGE PACIFIC LOW-LEVEL RIDGE. THE OFFICIAL
 FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS FORECAST AND IS
 AGAIN CLOSE TO THE GFS AND GFDN SOLUTIONS.
  
 THE ENTRAINMENT OF COLD AIR STRATOCUMULUS CLOUDS AND WEAKENING HAS
 BEEN INTERRUPTED. HOWEVER...BY 48 HOURS...THE CYCLONE CENTER IS
 FORECAST TO PASS OVER SUB-25C SST WATER WHICH SHOULD BRING ABOUT
 STEADY WEAKENING. UNFORTUNATELY...UNTIL THAT TIME...CELIA MAY
 CONTINUE TO HUG THE EAST-WEST INSTABILITY GRADIENT AND GENERATE AT
 LEAST INTERMITTENT CONVECTION AROUND THE LOW-LEVEL CENTER. THE
 SHIPS INTENSITY MODEL HAS CONTINUED ITS PREVIOUS TREND OF KEEPING
 CELIA BETWEEN 35-40 KT THROUGH 72 HOURS BEFORE SLOWLY WEAKENING THE
 CYCLONE AFTER THAT. GIVEN THAT THE UPPER-LEVEL ENVIRONMENT IS
 FORECAST TO REMAIN QUITE FAVORABLE...WITH VERTICAL SHEAR LESS THAN
 5 KT FOR THE NEXT 60 HOURS...THE FORECAST INTENSITY HAS BEEN HELD
 UP SLIGHTLY FOR THE NEXT 24 HOURS.
  
 FORECASTER STEWART
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      23/2100Z 16.1N 126.5W    35 KT
  12HR VT     24/0600Z 16.2N 127.9W    35 KT
  24HR VT     24/1800Z 16.3N 129.8W    30 KT
  36HR VT     25/0600Z 16.4N 131.6W    25 KT...DISSIPATING
  48HR VT     25/1800Z 16.4N 133.8W    25 KT...REMNANT LOW
  72HR VT     26/1800Z...DISSIPATED
  
  
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