000 WTNT44 KNHC 180837 TCDAT4 TROPICAL STORM HUMBERTO DISCUSSION NUMBER 32 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092013 500 AM AST WED SEP 18 2013 IF I JUST WENT BY THE LATEST SATELLITE INTENSITY ESTIMATES...I WOULD PROBABLY DOWNGRADE HUMBERTO TO A TROPICAL DEPRESSION. HOWEVER... TROPICAL CLASSIFICATIONS MIGHT NOT BE PURELY APPLICABLE IN THIS CASE...AND I WOULD RATHER WAIT UNTIL WE RECEIVE ADDITIONAL SUPPORTING DATA BEFORE DECREASING THE INITIAL INTENSITY. AN ARGUMENT COULD ALSO BE MADE THAT MORE DISTINCT BANDING FEATURES HAVE BEGUN TO FORM ON THE EASTERN SIDE OF THE CIRCULATION DURING THE PAST COUPLE OF HOURS...AND IN SOME SENSE HUMBERTO LOOKS A LITTLE MORE ORGANIZED NOW THAN IT DID LAST EVENING. THE LOW-LEVEL CENTER HAS BEEN INCREDIBLY DIFFICULT TO LOCATE... PARTIALLY BECAUSE CLOUDS ASSOCIATED A NEARBY UPPER-LEVEL LOW HAVE BEEN MASKING THE LOW CLOUD MOTIONS. THE BEST ESTIMATE OF THE INITIAL MOTION IS 335/7 KT...BUT HUMBERTO IS FORECAST TO TURN NORTHWARD VERY SOON BETWEEN HIGH PRESSURE NEAR THE AZORES AND A DEEP-LAYER TROUGH MOVING ACROSS THE WESTERN ATLANTIC. THE STORM SHOULD START FEELING THE EFFECTS OF FASTER MID-LATITUDE FLOW IN A DAY OR TWO...AND WILL ACCELERATE NORTH-NORTHEASTWARD TOWARD THE NORTH ATLANTIC BY 48 HOURS. THE SPREAD AMONG THE TRACK GUIDANCE IS FAIRLY NARROW...AND NO MAJOR CHANGES TO THE OFFICIAL TRACK FORECAST WERE REQUIRED ON THIS CYCLE. HUMBERTO WILL BE MOVING INTO A MORE DIFFLUENT UPPER-LEVEL REGIME IN ABOUT 24 HOURS...AND THE VERTICAL SHEAR SHOULD BE LOW ENOUGH TO AT LEAST ALLOW THE CYCLONE TO MAINTAIN ITS INTENSITY. EVEN THOUGH THE SHEAR IS FORECAST TO INCREASE SIGNIFICANTLY AFTER 48 HOURS...SOME STRENGTHENING IS STILL POSSIBLE DUE TO BAROCLINIC INFLUENCES. WITH THE EXCEPTION OF THE GFS...THE GLOBAL MODELS INDICATE THAT HUMBERTO COULD BE ABSORBED BY AN EXTRATROPICAL LOW BY DAY 4...AND THAT IS NOW INDICATED IN THE OFFICIAL FORECAST. FORECAST POSITIONS AND MAX WINDS INIT 18/0900Z 31.4N 43.7W 35 KT 40 MPH 12H 18/1800Z 32.2N 43.6W 35 KT 40 MPH 24H 19/0600Z 33.6N 43.5W 40 KT 45 MPH 36H 19/1800Z 35.1N 42.7W 40 KT 45 MPH 48H 20/0600Z 37.1N 41.1W 45 KT 50 MPH 72H 21/0600Z 45.0N 33.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 22/0600Z...ABSORBED $$ FORECASTER BERG