000 WTNT41 KNHC 220833 TCDAT1 TROPICAL DEPRESSION SIX DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010 500 AM AST SUN AUG 22 2010 SATELLITE IMAGES INDICATE THAT THE DEPRESSION IS GRADUALLY BECOMING BETTER ORGANIZED...WITH THE DEVELOPMENT IN THE LAST SEVERAL HOURS OF A DISTINCT CURVED BAND WRAPPING NEARLY HALFWAY AROUND THE WESTERN SIDE OF THE CIRCULATION. HOWEVER...THE CIRCULATION CENTER REMAINS SEPARATED FROM THE DEEP CONVECTION. SATELLITE INTENSITY ESTIMATES ARE AT 2.0 AND 2.5 FROM SAB AND TAFB...RESPECTIVELY. WITH THE LACK OF A CONSENSUS FROM BOTH SATELLITE AGENCIES AND LITTLE DEEP CONVECTION NEAR THE CENTER...THE INTENSITY IS HELD AT 30 KT FOR THIS ADVISORY. RECENT CENTER FIXES ARE A BIT UNCERTAIN GIVEN A LACK OF MICROWAVE DATA BUT YIELD AN INITIAL MOTION OF 295/08...A LITTLE TO THE RIGHT AND FASTER THAN THE PREVIOUS ESTIMATE. A DEEP LAYER EAST- SOUTHEASTERLY FLOW SOUTH OF A SUBTROPICAL RIDGE SHOULD STEER THE CYCLONE ON A GENERAL WEST-NORTHWESTWARD COURSE FOR THE NEXT COUPLE OF DAYS...WITH SOME INCREASE IN FORWARD SPEED. WATER VAPOR IMAGERY INDICATES A MID- TO UPPER-LEVEL LOW NEAR 27N41W THAT IS FORECAST BY THE GLOBAL MODELS TO MOVE SOUTHWEST AND CAUSE A DEVELOPING WEAKNESS IN THE RIDGE BETWEEN 45-50W IN ABOUT 72 HOURS. THE WEAKNESS IN THE RIDGE BECOMES MORE PRONOUNCED AS A LARGER MID-LATITUDE TROUGH IS FORECAST TO DIG OVER THE EAST CENTRAL ATLANTIC LATE IN THE FORECAST PERIOD. MODEL GUIDANCE IS NOW A BIT MORE DIVERGENT BUT SHOWS THE DEPRESSION MOVING WEST-NORTHWESTWARD TO NORTHWESTWARD WITH A DECREASE IN FORWARD SPEED AS IT MOVES INTO THE WEAKNESS. THE OFFICIAL NHC FORECAST TRACK IS SLOWED AT LATER FORECAST TIMES AS A RESULT OF A SLOWER TREND IN THE GUIDANCE AND INCREASING MODEL SPREAD. SHIPS MODEL OUTPUT AND UW-CIMSS SHEAR ANALYSES INDICATE MODERATE EAST-NORTHEASTERLY VERTICAL WIND SHEAR OVER THE CYCLONE...SEEMINGLY CONFIRMED BY THE EXPOSED NATURE OF THE CIRCULATION CENTER. HOWEVER...THE SHEAR IS EXPECTED TO DECREASE AS THE DEPRESSION MOVES OUT OF THE LOW-LEVEL MONSOONAL FLOW OVER THE EASTERN TROPICAL ATLANTIC. THE LOWER SHEAR ENVIRONMENT ALONG WITH INCREASING SSTS SHOULD FAVOR A GRADUAL INTENSIFICATION...AND THE DEPRESSION IS FORECAST TO REACH HURRICANE STRENGTH WITHIN 3 DAYS. THEREAFTER... AN INCREASE IN SOUTHWESTERLY VERTICAL WIND SHEAR ASSOCIATED WITH THE DIGGING TROUGH OVER THE CENTRAL ATLANTIC COULD HAMPER FURTHER INTENSIFICATION. THE OFFICIAL WIND SPEED FORECAST IS REDUCED ONLY SLIGHTLY FROM THE PREVIOUS ONE THROUGHOUT THE FORECAST PERIOD AND IS IN BEST AGREEMENT WITH THE LGEM STATISTICAL INTENSITY GUIDANCE. FORECAST POSITIONS AND MAX WINDS INITIAL 22/0900Z 12.1N 33.4W 30 KT 12HR VT 22/1800Z 12.6N 34.6W 35 KT 24HR VT 23/0600Z 13.4N 36.6W 40 KT 36HR VT 23/1800Z 14.4N 39.2W 45 KT 48HR VT 24/0600Z 15.5N 42.0W 55 KT 72HR VT 25/0600Z 18.5N 47.5W 75 KT 96HR VT 26/0600Z 22.0N 52.0W 85 KT 120HR VT 27/0600Z 24.5N 55.0W 90 KT $$ FORECASTER KIMBERLAIN