966 
 WTPZ43 KNHC 090244
 TCDEP3
  
 HURRICANE CALVIN DISCUSSION NUMBER   7
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP032011
 800 PM PDT FRI JUL 08 2011
  
 RECENT CONVENTIONAL AND EARLIER MICROWAVE SATELLITE DATA SUGGEST
 THAT THE LOW-LEVEL AND MID-/UPPER-LEVEL EYE FEATURES MAY HAVE
 FINALLY BECOME VERTICALLY ALIGNED. IN ADDITION...A WARM SPOT HAS
 DEVELOPED NEARLY IN THE CENTER OF THE SMALLER BUT BETTER-DEFINED
 CDO CLOUD PATTERN...SUGGESTING THE PRESENCE OF A MORE VERTICAL EYE
 STRUCTURE. SATELLITE INTENSITY ESTIMATES ARE 77 KT AND 65 KT FROM
 TAFB AND SAB...RESPECTIVELY. GIVEN THE IMPROVEMENT IN THE OVERALL
 CLOUD PATTERN...THE INITIAL INTENSITY HAS BEEN BUMPED UP TO 70 KT.
 
 THE INITIAL MOTION IS 285/10...BUT THIS IS LIKELY JUST A TEMPORARY
 MOTION. CALVIN HAS WOBBLED TO THE RIGHT A LITTLE BIT...PROBABLY AS
 A RESULT OF THE LOW-LEVEL AND MID-LEVEL EYES BECOMING VERTICALLY
 ALIGNED. AS A RESULT...CALVIN IS FORECAST TO RETURN TO A MORE
 WESTERLY BASE COURSE WITHIN THE NEXT 12 HOURS OR SO DUE TO THE
 STRONG SUBTROPICAL RIDGE SITUATED TO THE NORTH OF THE CYCLONE. THE
 AFOREMENTIONED RIDGE IS EXPECTED TO CHANGE LITTLE THROUGH THE
 FORECAST PERIOD...WHICH SHOULD ACT TO KEEP CALVIN MOVING IN A
 WESTWARD TO WEST-NORTHWESTWARD DIRECTION. BY 48 HOURS...THE CYCLONE
 IS FORECAST TO BEGIN DEGENERATING INTO A REMNANT LOW PRESSURE
 SYSTEM AS IT MOVES OVER SUB-24C SSTS. AS THE SYSTEM BECOMES
 VERTICALLY SHALLOW...IT IS EXPECTED TO SLOW DOWN CONSIDERABLY AS IT
 MOVES INTO A REGION OF ABNORMALLY WEAK LOW-LEVEL TRADE WIND FLOW.
 THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY AND IS NEAR
 THE CONSENSUS OF THE GLOBAL MODELS.
 
 UPPER-LEVEL OUTFLOW HAS IMPROVED AND EXPANDED IN ALL QUADRANTS...
 SUGGESTING THAT THE VERTICAL SHEAR HAS ABATED SOMEWHAT.
 THEREFORE...SOME SLIGHT STRENGTHENING IS POSSIBLE DURING THE NEXT 6
 HOURS OR SO SINCE CALVIN WILL STILL BE OVER AT LEAST 26C SSTS.
 HOWEVER...BY 12 HOURS THE CYCLONE WILL BE MOVING OVER MUCH COOLER
 WATER AND ALSO BEGIN INGESTING MORE STABLE AIR AS INDICATED BY A
 LARGE FIELD OF LOW-LEVEL STRATOCUMULUS CLOUDS LOCATED JUST WEST OF
 CALVIN. AS A RESULT OF THE POOR OCEANIC AND THERMODYNAMIC
 CONDITIONS AHEAD OF THE HURRICANE...STEADY WEAKENING IS FORECAST
 AND AT A FASTER RATE THAN INDICATED BY THE SHIPS AND LGEM
 STATISTICAL INTENSITY MODELS.
 
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  09/0300Z 16.6N 109.5W   70 KT  80 MPH
  12H  09/1200Z 17.0N 111.0W   60 KT  70 MPH
  24H  10/0000Z 17.5N 112.6W   50 KT  60 MPH
  36H  10/1200Z 17.9N 113.9W   40 KT  45 MPH
  48H  11/0000Z 18.4N 115.1W   30 KT  35 MPH
  72H  12/0000Z 19.3N 117.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
  96H  13/0000Z 19.5N 118.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 120H  14/0000Z...DISSIPATED
  
 $$
 FORECASTER STEWART