000 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 000 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