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| #300086 (Received by flhurricane at: 4:49 AM 07.Oct.2009) TCDAT5 TROPICAL STORM HENRI DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102009 500 AM AST WED OCT 07 2009 INFRARED SATELLITE IMAGERY AFTER THE ECLIPSE SHOWS A LARGE MASS OF VIGOROUS DEEP CONVECTION ASSOCIATED WITH HENRI...WITH CLOUD TOP TEMPERATURES COLDER THAN -80C. IN FACT...THE AREAL COVERAGE OF DEEP CONVECTION HAS EXPANDED CONSIDERABLY SINCE YESTERDAY EVENING... THOUGH THERE ARE NO BANDING FEATURES. HOWEVER...A 0531 UTC AMSR-E PASS INDICATED THAT THE CENTER WAS STILL PARTIALLY EXPOSED... LOCATED ON THE WESTERN EDGE OF THE MAIN CONVECTIVE CLUSTER. BASED UPON THE IMPROVEMENT IN ORGANIZATION DURING THE PAST SEVERAL HOURS...THE INITIAL INTENSITY IS RAISED TO 45 KT IN ACCORDANCE WITH 0600 UTC DVORAK CLASSIFICATIONS OF 3.0 FROM TAFB AND RECENT OBJECTIVE ESTIMATES NEAR 3.0 FROM UW CIMSS. PERSISTENT SOUTHWESTERLY SHEAR OF 20-25 KT CONTINUES TO PREVENT HENRI FROM STRENGTHENING MUCH. SHIPS MODEL GUIDANCE INDICATES THAT HIGH WESTERLY SHEAR SHOULD PREVAIL OVER HENRI FOR AT LEAST THE NEXT 24 HOURS...WITH A POSSIBLE RELAXATION THEREAFTER. THIS DOES NOT SEEM ENTIRELY REALISTIC...AS A MAJORITY OF GLOBAL MODELS INDICATE THAT HENRI SHOULD CROSS A SHARP SHEAR AXIS NORTH OF THE NORTHEAST CARIBBEAN ISLANDS IN 36-48 HOURS AND ENCOUNTER STRONG UPPER-LEVEL NORTHERLY OR NORTHEASTERLY FLOW. SHIPS MODEL OUTPUT ALSO FORECASTS HENRI TO ENCOUNTER A CONVERGENT UPPER-LEVEL FLOW AND A RATHER ANTICYCLONIC LOWER TROPOSPHERIC ENVIRONMENT...BOTH OF WHICH WOULD HAVE A NEGATIVE INFLUENCE ON THE CYCLONE. GIVEN THESE FACTORS...THE OFFICIAL FORECAST IS IN LINE WITH THE PREVIOUS ADVISORY AND A MAJORITY OF LARGE-SCALE DYNAMICAL MODELS...CALLING FOR THE DISSIPATION OF HENRI WITHIN 48 HOURS. LATEST CENTER FIXES SUGGEST A RATHER UNCERTAIN INITIAL MOTION. FORTUNATELY...A 0531 UTC AMSR-E PASS HAS ALLOWED FOR A MORE CONFIDENT INITIAL MOTION ESTIMATE OF 280/11...FARTHER LEFT THAN IN THE PREVIOUS ADVISORY. THE DOMINANT STEERING IS BEING PROVIDED BY MID-LEVEL SUBTROPICAL RIDGING NORTH OF HENRI...WITH A MINOR WEAKNESS AT UPPER LEVELS NORTHWEST OF THE CYCLONE. THIS FLOW PATTERN SHOULD FAVOR A GENERALLY WESTWARD TO WEST-NORTHWESTWARD TRACK UNTIL DISSIPATION. THE OFFICIAL FORECAST IS NUDGED SOUTH OF THE PREVIOUS ADVISORY TO ACCOUNT FOR ITS MORE SOUTHERN INITIAL POSITION AND MORE WESTERLY MOTION. FORECAST POSITIONS AND MAX WINDS INITIAL 07/0900Z 18.1N 56.1W 45 KT 12HR VT 07/1800Z 18.9N 58.0W 45 KT 24HR VT 08/0600Z 20.0N 60.3W 40 KT 36HR VT 08/1800Z 21.2N 62.5W 30 KT 48HR VT 09/0600Z 21.2N 63.2W 25 KT...REMNANT LOW 72HR VT 10/0600Z...DISSIPATED $$ FORECASTER KIMBERLAIN |
