000 WTNT42 KNHC 260848 TCDAT2 TROPICAL STORM EARL DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072010 500 AM AST THU AUG 26 2010 CONVENTIONAL SATELLITE IMAGERY INDICATES THAT THE SPIRAL BANDS AROUND EARL HAVE BECOME BETTER ORGANIZED THIS MORNING... PARTICULARLY OVER THE WESTERN PORTION OF THE CYCLONE. THE CYCLONE STRUCTURE...HOWEVER...IS STILL A BIT ELONGATED ALONG A SOUTHWEST TO NORTHEAST AXIS. DVORAK SATELLITE CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 AND 35 KT..RESPECTIVELY. USING A BLEND OF THE TWO...THE INITIAL INTENSITY IS INCREASED TO 40 KT. THE OCEAN IS WARM AND THE SHEAR IS LOW...CREATING AN ENVIRONMENT CONDUCIVE FOR STRENGTHENING DURING THE ENTIRE FORECAST PERIOD. IN FACT...THE LGEM...HWRF...AND SHIPS MODELS ALL SHOW THE CYCLONE BECOMING A HURRICANE IN 2 DAYS. THE OFFICIAL FORECAST FOLLOWS SUIT AND ALSO BRINGS EARL TO CATEGORY TWO INTENSITY BY DAY 5. THE CENTER OF EARL HAS BEEN RATHER DIFFICULT TO LOCATE THIS MORNING. A 2315 UTC ASCAT OVERPASS INDICATED AN ELONGATED CENTER NEAR THE CONVECTION OVER THE SOUTHERN PORTION OF THE SYSTEM...WELL TO THE SOUTH OF THE PREVIOUS ADVISORY POSITION. HOWEVER...A SUBSEQUENT AMSU-B MICROWAVE PASS AT 2318 UTC AND A RECENT 0430 UTC TRMM IMAGE SUGGESTED THE CENTER IS LOCATED TO THE NORTHEAST OF THE AFOREMENTIONED ASCAT PASS...MUCH CLOSER TO THE PREVIOUS BEST TRACK. FOR THIS ADVISORY...AND BASED ON THESE DATA...CONTINUITY WILL BE MAINTAINED AND THE INITIAL POSITION IS BE NEAR THE NORTHERN CLUSTER OF DEEP CONVECTION AND CLOSE TO THE TRMM FIX. IF THE CIRCULATION CENTER DOES REFORM FARTHER SOUTH...THE FORECAST TRACK WILL HAVE TO BE ADJUSTED SOUTH...OR TO THE LEFT OF THIS ADVISORY PACKAGE. EARL IS MOVING TOWARD THE WEST-NORTHWEST...AN ESTIMATED 285 DEGREES AT 13 KT. THE TROPICAL STORM IS EMBEDDED WITHIN THE DEEP TROPICAL ATLANTIC TRADE WIND FLOW AND SHOULD CONTINUE ON THIS GENERAL TRACK OVER THE NEXT 48 TO 72 HOURS. AFTERWARD...A TURN TOWARD THE WEST-NORTHWEST IS EXPECTED AS THE CYCLONE BEGINS TO MOVE TOWARD A BREAK IN THE SUBTROPICAL RIDGE. WITH THE EXCEPTION OF NOGAPS AND THE NAVY GFDN...WHICH ARE BOTH INDICATING AN EARLIER TURN TOWARD THE NORTHWEST...THE DYNAMICAL MODELS ARE TIGHTLY CLUSTERED THROUGH DAY 5. THE NHC FORECAST TRACK IS BASED ON THE TVCN MODEL CONSENSUS AND IS CLOSE TO THE ECMWF AND GFS. FORECAST POSITIONS AND MAX WINDS INITIAL 26/0900Z 15.2N 34.8W 40 KT 12HR VT 26/1800Z 15.7N 37.2W 45 KT 24HR VT 27/0600Z 16.4N 40.3W 50 KT 36HR VT 27/1800Z 16.6N 43.7W 60 KT 48HR VT 28/0600Z 16.7N 47.0W 70 KT 72HR VT 29/0600Z 17.9N 52.3W 80 KT 96HR VT 30/0600Z 20.0N 57.0W 90 KT 120HR VT 31/0600Z 22.5N 60.0W 95 KT $$ FORECASTER ROBERTS/BRENNAN