000 WTNT42 KNHC 261459 TCDAT2 TROPICAL STORM EARL DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072010 1100 AM AST THU AUG 26 2010 VISIBLE AND MICROWAVE SATELLITE IMAGERY INDICATE EARL HAS NOT BECOME ANY BETTER ORGANIZED SINCE THE LAST ADVISORY. IN FACT...THE INNER CORE CONVECTION HAS ERODED DUE TO DRY AIR ENTRAINMENT NOTED IN CONVENTIONAL WATER VAPOR IMAGERY AND IN A 0735Z SSMI WATER VAPOR IMAGE. THE INITIAL INTENSITY WILL REMAIN 40 KT FOR THIS ADVISORY BASED ON A BLEND OF SATELLITE INTENSITY ESTIMATES OF 45 KT AND 35 KT FROM TAFB AND SAB...RESPECTIVELY. THE CENTER OF EARL HAS BEEN REPOSITIONED ABOUT 30 NMI SOUTH OF THE PREVIOUS ADVISORY AND FORECAST TRACK BASED ON A BLEND OF VISIBLE AND MICROWAVE FIXES. THE INITIAL MOTION ESTIMATE IS A 24-HOUR AVERAGE OF 275/15...AFTER SMOOTHING THROUGH ALL THE WIGGLES AND WOBBLES IN THE FIXES. THE OFFICIAL FORECAST TRACK WAS SHIFTED SOUTH OF THE PREVIOUS ADVISORY DUE IN PART TO THE MORE SOUTHWARD INITIAL POSITION. OTHERWISE...THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS TRACK REASONING. EARL IS EXPECTED TO MOVE STEADILY WEST TO WEST-NORTHWESTWARD FOR THE NEXT 72 HOURS AND THEN GRADUALLY TURN NORTHWESTWARD AND SLOW DOWN AS THE CYCLONE APPROACHES A WEAKNESS IN THE SUBTROPICAL RIDGE BETWEEN BERMUDA AND THE LEEWARD ISLANDS. THIS WEAKNESS IN THE STEERING FLOW IS THE COMBINED EFFECTS OF HURRICANE DANIELLE AND A MID-LATITUDE TROUGH FORECAST TO CAPTURE AND LIFT OUT THAT HURRICANE TO THE NORTHEAST. IF DANIELLE RECURVES FASTER THAN CURRENTLY EXPECTED...WHICH THE UKMET AND ECMWF ARE HINTING AT... THEN THE RIDGE TO THE NORTH OF EARL COULD BUILD BACK IN SOONER AND KEEP EARL ON A SLOWER WEST-NORTHWESTWARD TRACK THAN INDICATED BY THE OFFICIAL FORECAST TRACK. THE ADVISORY TRACK LIES ALONG THE NORTHERN EDGE OF THE TIGHTLY PACKED MODEL GUIDANCE SUITE AND SIMILAR TO THE SPEED OF THE CONSENSUS MODEL...TVCN. ALL OF THE MODELS INDICATE THAT THE VERTICAL SHEAR SHOULD REMAIN QUITE LOW THROUGH 72 HOURS OR SO...WHICH WOULD FAVOR SIGNIFICANT INTENSIFICATION. HOWEVER...THE DRY MID-LEVEL ENVIRONMENT THAT EARL IS FORECAST TO MOVE THROUGH DURING THAT TIME IS EXPECTED TO RESULT IN A SLOWER THAN NORMAL RATE OF INTENSIFICATION. HOWEVER...BY DAYS 4 AND 5...EARL IS FORECAST TO MOVE INTO THE SOUTHWESTERLY PERIPHERY OF SYNOPTIC-SCALE 200 MB ANTICYCLONE...WHICH GENERALLY FAVORS DEVELOPMENT DUE TO ENHANCED OUTFLOW TO THE NORTH AND SOUTH OF THE CYCLONE. IT IS POSSIBLE THAT EARL COULD REACH MAJOR HURRICANE STRENGTH BY THAT TIME...AS INDICATED BY THE HWRF MODEL. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE VARIOUS INTENSITY MODELS. FORECAST POSITIONS AND MAX WINDS INITIAL 26/1500Z 14.9N 37.1W 40 KT 12HR VT 27/0000Z 15.4N 39.4W 45 KT 24HR VT 27/1200Z 15.7N 42.6W 50 KT 36HR VT 28/0000Z 16.1N 46.0W 55 KT 48HR VT 28/1200Z 16.5N 49.1W 65 KT 72HR VT 29/1200Z 17.8N 54.4W 75 KT 96HR VT 30/1200Z 20.0N 58.5W 85 KT 120HR VT 31/1200Z 22.5N 61.0W 95 KT $$ FORECASTER STEWART