000 WTNT42 KNHC 010248 TCDAT2 HURRICANE EARL DISCUSSION NUMBER 27 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072010 1100 PM AST TUE AUG 31 2010 EARL REMAINS A WELL-ORGANIZED HURRICANE ON SATELLITE IMAGES. AN EYE OF ABOUT 20 N MI IN DIAMETER IS EVIDENT ON THE INFRARED IMAGES... AND THE UPPER-LEVEL OUTFLOW IS WELL-DEFINED OVER ALL BUT THE SOUTHWEST PART OF THE CIRCULATION...AS CONFIRMED BY SURVELLIANCE DATA FROM THE NOAA G-IV JET THIS EVENING. THE INITIAL INTENSITY IS KEPT AT 115 KT BASED ON A DVORAK ESTIMATE FROM TAFB. THERE IS CURRENTLY ABOUT 20 KT OF SOUTHWESTERLY SHEAR OVER EARL AS DEPICTED BY UW-CIMSS ANALYSES. THIS SHEAR SHOULD LESSEN AS AN UPPER-LEVEL TROUGH...JUST TO THE WEST AND NORTHWEST OF THE HURRICANE...IS PREDICTED BY THE GLOBAL MODELS TO SHIFT WESTWARD OVER THE NEXT DAY OR SO. THIS EVOLUTION OF THE UPPER-LEVEL ENVIRONMENT SHOULD ALLOW EARL TO MORE OR LESS MAINTAIN ITS INTENSITY FOR ABOUT THE NEXT 36 HOURS. THE NHC INTENSITY FORECAST IS ONLY A LITTLE ABOVE THE STATISTICAL/DYNAMICAL LGEM GUIDANCE AND A LITTLE BELOW THE GFDL HURRICANE MODEL GUIDANCE. BY DAY 4...GLOBAL MODELS SHOW EARL BECOME EMBEDDED WITHIN A BAROCLINIC ZONE WITH WELL-DEFINED THERMAL ADVECTION SO EXTRATROPICAL TRANSITION SHOULD HAVE OCCURRED BY THAT TIME. THE TRACK HAS BEEN WOBBLING AS IS TYPICAL OF INTENSE HURRICANES BUT THE MEAN MOTION OVER THE PAST 6 HOURS IS ABOUT 310/13. THERE HAS BEEN LITTLE CHANGE TO THE NHC FORECAST TRACK OR REASONING. EARL IS EXPECTED TO GRADUALLY TURN TO THE RIGHT AS IT MOVES AROUND THE WESTERN PERIPHERY OF A MID-LEVEL SUBTROPICAL ANTICYCLONE FOR THE NEXT COUPLE OF DAYS. AFTERWARDS...A VIGOROUS MID-LATITUDE TROUGH AT 500 MB WILL APPROACH THE EAST COAST AND SHOULD CAUSE THE HURRICANE TO TURN TOWARD THE NORTH-NORTHEAST. OF COURSE...THE TIMING OF THIS TURN IS CRITICAL IN DETERMINING HOW CLOSE THE CENTER WILL COME TO THE U.S. EAST COAST. ONE SHOULD NOT FOCUS ON THE EXACT FORECAST TRACK BECAUSE OF FORECAST UNCERTAINTY...AND ALSO BECAUSE EARL IS A LARGE HURRICANE AND SIGNIFICANT IMPACTS CAN BE WELL REMOVED FROM THE CENTER. FORECAST POSITIONS AND MAX WINDS INITIAL 01/0300Z 23.0N 69.9W 115 KT 12HR VT 01/1200Z 24.5N 71.6W 115 KT 24HR VT 02/0000Z 27.0N 73.5W 115 KT 36HR VT 02/1200Z 29.8N 75.0W 115 KT 48HR VT 03/0000Z 32.7N 75.2W 110 KT 72HR VT 04/0000Z 39.0N 70.5W 90 KT 96HR VT 05/0000Z 47.0N 62.0W 75 KT...POST-TROP/EXTRATROP 120HR VT 06/0000Z 56.0N 58.0W 50 KT...POST-TROP/EXTRATROP $$ FORECASTER PASCH/KIMBERLAIN