000 WTNT42 KNHC 280857 TCDAT2 TROPICAL STORM EARL DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072010 500 AM AST SAT AUG 28 2010 EARL HAS BECOME BETTER ORGANIZED THIS MORNING. THE CLOUD PATTERN CONSISTS OF A CENTRAL DENSE OVERCAST WITH CLOUD TOPS TO -80 C AND A LARGE CURVED BAND OVER THE WESTERN SEMICIRCLE OF THE STORM. THE CIRRUS OUTFLOW HAS IMPROVED TO THE SOUTH AND WEST OF THE CENTER BUT REMAINS RESTRICTED OVER THE EASTERN SEMICIRCLE. DVORAK CLASSIFICATIONS ARE 45 KT AND 55 KT FROM TAFB AND SAB... RESPECTIVELY. ON THIS BASIS...THE INITIAL INTENSITY IS INCREASED TO 50 KT FOR THIS ADVISORY. A 0413 UTC TRMM OVERPASS INDICATED THAT THE LOW-LEVEL CENTER OF EARL WAS LOCATED A LITTLE TO THE SOUTH OF THE PREVIOUS ESTIMATES. USING A COMBINATION OF THIS OVERPASS AND SATELLITE FIXES YIELDS AN INITIAL MOTION OF 270/18. A MID-LEVEL RIDGE LOCATED OVER THE SUBTROPICAL CENTRAL ATLANTIC IS EXPECTED TO KEEP EARL ON A RATHER QUICK WESTWARD TO WEST-NORTHWESTWARD COURSE FOR THE NEXT DAY OR TWO. THEREAFTER...THE CYCLONE IS EXPECTED TO NEAR A BREAK IN THE RIDGE...AND THAT SHOULD CAUSE A TURN TO THE NORTHWEST. WHILE THE GLOBAL MODELS AGREE ON THE GENERAL EVOLUTION OF THE LARGE SCALE PATTERN...THERE ARE CONSIDERABLE DIFFERENCES ON THE DETAILS OF THE TIMING...LOCATION AND SHARPNESS OF THE TURN. THE OFFICIAL FORECAST IS NUDGED A LITTLE TO THE LEFT OF THE PREVIOUS ONE TO ACCOUNT FOR THE INITIAL POSITION AND MOTION AND TRENDS TOWARD THE MULTI-MODEL CONSENSUS. ALL OF THE INTENSITY GUIDANCE SHOWS ADDITIONAL INTENSIFICATION DURING THE NEXT FEW DAYS...AS EARL MOVES OVER EVEN WARMER WATERS AND INTO A MORE FAVORABLE UPPER-LEVEL WIND ENVIRONMENT. THE OFFICIAL FORECAST IS ADJUSTED UPWARD FOR THE FIRST COUPLE OF DAYS AND NOW BRINGS EARL TO HURRICANE STRENGTH IN 24 HOURS AND TO MAJOR HURRICANE STATUS IN 3 DAYS. BEYOND 72 HOURS...SOUTHWESTERLY SHEAR IS EXPECTED TO INCREASE...WHICH SHOULD HALT INTENSIFICATION AND POSSIBLY INDUCE GRADUAL WEAKENING. THIS IS REFLECTED IN THE OFFICIAL FORECAST...WHICH IS IN BEST AGREEMENT WITH THE INTENSITY MODEL CONSENSUS. THE FORECAST NECESSITATES THE ISSUANCE OF TROPICAL STORM WATCHES FOR PORTIONS OF THE NORTHERN LEEWARD ISLANDS. FORECAST POSITIONS AND MAX WINDS INITIAL 28/0900Z 15.7N 50.1W 50 KT 12HR VT 28/1800Z 16.0N 52.7W 60 KT 24HR VT 29/0600Z 16.5N 55.7W 65 KT 36HR VT 29/1800Z 17.2N 58.3W 75 KT 48HR VT 30/0600Z 18.2N 60.5W 85 KT 72HR VT 31/0600Z 20.8N 64.2W 100 KT 96HR VT 01/0600Z 24.5N 67.5W 110 KT 120HR VT 02/0600Z 29.5N 69.5W 100 KT $$ FORECASTER CANGIALOSI/BRENNAN