000 WTNT42 KNHC 281436 TCDAT2 TROPICAL STORM EARL DISCUSSION NUMBER 13 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072010 1100 AM AST SAT AUG 28 2010 ALTHOUGH THE CIRCULATION CONTINUES TO BE LARGE AND VIGOROUS AND THE AMOUNT OF DEEP CONVECTION HAS INCREASED SINCE YESTERDAY...VISIBLE IMAGES INDICATE THAT CENTER HAS BECOME EXPOSED AND IS LOCATED ON THE NORTHWESTERN SIDE OF THE DEEP CONVECTION. THIS HAS RESULTED FROM SOME MODEST NORTHERLY SHEAR CAUSED BY THE OUTFLOW OF LARGER HURRICANE DANIELLE. ALTHOUGH THE CYCLONE IS LESS ORGANIZED THAN EARLIER TODAY...T-NUMBERS HAVE NOT CHANGED MUCH AND THE INITIAL INTENSITY IS KEPT AT 50 KNOTS...BUT THE INTENSITY COULD BE LOWER. THE CURRENT NORTHERLY SHEAR IS EXPECTED TO ABATE SOON AS DANIELLE MOVES NORTHWARD AND...IN FACT...MOST OF THE GLOBAL MODELS SHOW THE UPPER-LEVEL FLOW BECOMING MORE FAVORABLE FOR INTENSIFICATION BY SUNDAY. THIS FLOW PATTERN...IN COMBINATION WITH A WARM OCEAN ALONG THE TRACK...WOULD RESULT IN INTENSIFICATION. EARL IS FORECAST TO BECOME A HURRICANE BY SUNDAY WITH A STEADY INTENSIFICATION THEREAFTER. EARL IS MOVING TOWARD THE WEST OR 275 DEGREES AT ABOUT 16 OR 17 KNOTS STEERED BY THE FLOW TO THE SOUTH OF A SUBTROPICAL RIDGE. HOWEVER...IN A DAY OR SO...EARL WILL BE APPROACHING THE WESTERN EDGE OF THE RIDGE AND THE CYCLONE SHOULD BEGIN TO TURN MORE TO THE WEST-NORTHWEST AND NORTHWEST. THE TRACK MODELS DIVERGE BEYOND 48 HOURS BUT ONCE AGAIN...THE OFFICIAL FORECAST AND THE GUIDANCE ENVELOPE HAVE SHIFTED A LITTLE BIT SOUTHWARD AND WESTWARD. NEVERTHELESS...THE EXPECTED STEERING PATTERN STILL FAVORS A GRADUAL TURN TO THE WEST-NORTHWEST DURING THE NEXT DAY OR TWO. AT THIS TIME...IT IS NOT NECESSARY TO CHANGE THE TROPICAL STORM WATCH FOR THE NORTHERN LEEWARD ISLANDS BUT A DEVIATION OF THE TRACK TO THE WEST WOULD REQUIRE ADDITIONAL WATCHES OR WARNINGS. A NOAA-P3 AIRCRAFT RESEARCH MISSION WILL PROBABLY CHECK THE SYSTEM LATER TODAY WHILE A NOAA GULFSTREAM JET SAMPLES THE ENVIRONMENT. THE FIRST AIR FORCE RECONNAISSANCE AIRCRAFT INTO EARL IS SCHEDULED FOR EARLY SUNDAY. FORECAST POSITIONS AND MAX WINDS INITIAL 28/1500Z 16.0N 51.8W 50 KT 12HR VT 29/0000Z 16.1N 54.3W 55 KT 24HR VT 29/1200Z 17.0N 57.5W 65 KT 36HR VT 30/0000Z 17.8N 60.0W 75 KT 48HR VT 30/1200Z 18.7N 62.0W 85 KT 72HR VT 31/1200Z 21.5N 66.0W 95 KT 96HR VT 01/1200Z 25.0N 69.0W 100 KT 120HR VT 02/1200Z 30.0N 71.0W 100 KT $$ FORECASTER AVILA