000 WTPZ43 KNHC 080238 TCDEP3 TROPICAL STORM CALVIN DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032011 800 PM PDT THU JUL 07 2011 CONVENTIONAL SATELLITE IMAGERY INDICATES THE CLOUD PATTERN WENT THROUGH A BRIEF BURSTING PHASE EARLIER THIS AFTERNOON...BUT HAS SINCE DECREASED IN BOTH VERTICAL EXTENT AND AREAL COVERAGE. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE T3.0/45 KT AND T2.5/35 KT...RESPECTIVELY...AND UW-CIMSS ADT VALUES ARE T2.9/43 KT. MICROWAVE SATELLITE DATA INDICATE THE MID-LEVEL CIRCULATION CENTER IS SHEARED AT LEAST 45 NMI TO THE NORTHWEST OF THE LOW-LEVEL CENTER. THEREFORE...THE INITIAL INTENSITY HAS ONLY BEEN INCREASED TO 35 KT DESPITE THE HIGHER INTENSITY ESTIMATES...WHICH STILL MAKES THE CYCLONE THE THIRD TROPICAL STORM OF THE SEASON. UPPER-LEVEL OUTFLOW REMAINS GOOD IN THE WESTERN SEMICIRCLE BUT RESTRICTED ELSEWHERE. THE INITIAL MOTION ESTIMATE OF 290/12 IS BASED ON EXTRAPOLATION... CONTINUITY WITH THE PREVIOUS FORECAST...AND EARLIER MICROWAVE FIXES. CALVIN IS EXPECTED TO REMAIN EMBEDDED WITHIN DEEP-LAYER EAST-SOUTHEASTERLY FLOW ALONG THE SOUTHERN PERIPHERY OF A LARGE SUBTROPICAL RIDGE THAT EXTENDS FROM THE U.S. SOUTHERN PLAINS WESTWARD ACROSS NORTHERN AND CENTRAL MEXICO. THE GLOBAL MODELS BASICALLY MAINTAIN THE STRENGTH AND POSITION OF THE RIDGE THROUGHOUT THE FORECAST PERIOD...WHICH SHOULD KEEP CALVIN MOVING IN A GENERAL WEST-NORTHWESTWARD DIRECTION. AS MENTIONED IN THE PREVIOUS DISCUSSION...THE HWRF...GFDL...AND GFDN MODELS TAKE THE CYCLONE NORTHWARD INTO A WEAKENING RIDGE BY 36 HOURS...WHICH APPEARS UNLIKELY GIVEN THE CURRENT STRENGTH OF THE RIDGE. THESE MODELS ARE...THEREFORE...CONSIDERED TO BE OUTLIER SOLUTIONS. BY 72 HOURS...CALVIN IS EXPECTED TO WEAKEN INTO A SHALLOW REMNANT LOW PRESSURE SYSTEM AS IT MOVES OVER 23C SSTS...AND BE STEERED MORE WESTWARD BY LOW-LEVEL EASTERLY TRADE WINDS. THE OFFICIAL FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS ADVISORY TRACK AND LIES NEAR THE MIDDLE OF THE GLOBAL MODELS ENVELOPE. EASTERLY VERTICAL WIND SHEAR OF 20 KT IS FORECAST TO WEAKEN TO NEAR 10 KT BY 24-36 HOURS...WHICH SHOULD ALLOW THE CYCLONE TO GRADUALLY STRENGTHEN. HOWEVER...THE MOST FAVORABLE UPPER-LEVEL OUTFLOW PATTERN IS NOT EXPECTED TO OCCUR UNTIL AFTER 48 HOURS...AT WHICH TIME CALVIN IS FORECAST TO BE OVER MUCH COOLER WATER. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS A BLEND OF THE SHIPS AND LGEM INTENSITY MODELS. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 16.0N 104.3W 35 KT 40 MPH 12H 08/1200Z 16.6N 105.7W 40 KT 45 MPH 24H 09/0000Z 17.4N 107.6W 50 KT 60 MPH 36H 09/1200Z 18.0N 109.2W 55 KT 65 MPH 48H 10/0000Z 18.5N 110.4W 45 KT 50 MPH 72H 11/0000Z 19.4N 112.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 12/0000Z 20.5N 116.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 13/0000Z...DISSIPATED $$ FORECASTER STEWART 000 WTPZ43 KNHC 080238 TCDEP3 TROPICAL STORM CALVIN DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032011 800 PM PDT THU JUL 07 2011 CONVENTIONAL SATELLITE IMAGERY INDICATES THE CLOUD PATTERN WENT THROUGH A BRIEF BURSTING PHASE EARLIER THIS AFTERNOON...BUT HAS SINCE DECREASED IN BOTH VERTICAL EXTENT AND AREAL COVERAGE. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE T3.0/45 KT AND T2.5/35 KT...RESPECTIVELY...AND UW-CIMSS ADT VALUES ARE T2.9/43 KT. MICROWAVE SATELLITE DATA INDICATE THE MID-LEVEL CIRCULATION CENTER IS SHEARED AT LEAST 45 NMI TO THE NORTHWEST OF THE LOW-LEVEL CENTER. THEREFORE...THE INITIAL INTENSITY HAS ONLY BEEN INCREASED TO 35 KT DESPITE THE HIGHER INTENSITY ESTIMATES...WHICH STILL MAKES THE CYCLONE THE THIRD TROPICAL STORM OF THE SEASON. UPPER-LEVEL OUTFLOW REMAINS GOOD IN THE WESTERN SEMICIRCLE BUT RESTRICTED ELSEWHERE. THE INITIAL MOTION ESTIMATE OF 290/12 IS BASED ON EXTRAPOLATION... CONTINUITY WITH THE PREVIOUS FORECAST...AND EARLIER MICROWAVE FIXES. CALVIN IS EXPECTED TO REMAIN EMBEDDED WITHIN DEEP-LAYER EAST-SOUTHEASTERLY FLOW ALONG THE SOUTHERN PERIPHERY OF A LARGE SUBTROPICAL RIDGE THAT EXTENDS FROM THE U.S. SOUTHERN PLAINS WESTWARD ACROSS NORTHERN AND CENTRAL MEXICO. THE GLOBAL MODELS BASICALLY MAINTAIN THE STRENGTH AND POSITION OF THE RIDGE THROUGHOUT THE FORECAST PERIOD...WHICH SHOULD KEEP CALVIN MOVING IN A GENERAL WEST-NORTHWESTWARD DIRECTION. AS MENTIONED IN THE PREVIOUS DISCUSSION...THE HWRF...GFDL...AND GFDN MODELS TAKE THE CYCLONE NORTHWARD INTO A WEAKENING RIDGE BY 36 HOURS...WHICH APPEARS UNLIKELY GIVEN THE CURRENT STRENGTH OF THE RIDGE. THESE MODELS ARE...THEREFORE...CONSIDERED TO BE OUTLIER SOLUTIONS. BY 72 HOURS...CALVIN IS EXPECTED TO WEAKEN INTO A SHALLOW REMNANT LOW PRESSURE SYSTEM AS IT MOVES OVER 23C SSTS...AND BE STEERED MORE WESTWARD BY LOW-LEVEL EASTERLY TRADE WINDS. THE OFFICIAL FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS ADVISORY TRACK AND LIES NEAR THE MIDDLE OF THE GLOBAL MODELS ENVELOPE. EASTERLY VERTICAL WIND SHEAR OF 20 KT IS FORECAST TO WEAKEN TO NEAR 10 KT BY 24-36 HOURS...WHICH SHOULD ALLOW THE CYCLONE TO GRADUALLY STRENGTHEN. HOWEVER...THE MOST FAVORABLE UPPER-LEVEL OUTFLOW PATTERN IS NOT EXPECTED TO OCCUR UNTIL AFTER 48 HOURS...AT WHICH TIME CALVIN IS FORECAST TO BE OVER MUCH COOLER WATER. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS A BLEND OF THE SHIPS AND LGEM INTENSITY MODELS. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 16.0N 104.3W 35 KT 40 MPH 12H 08/1200Z 16.6N 105.7W 40 KT 45 MPH 24H 09/0000Z 17.4N 107.6W 50 KT 60 MPH 36H 09/1200Z 18.0N 109.2W 55 KT 65 MPH 48H 10/0000Z 18.5N 110.4W 45 KT 50 MPH 72H 11/0000Z 19.4N 112.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 12/0000Z 20.5N 116.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 13/0000Z...DISSIPATED $$ FORECASTER STEWART