ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM HUMBERTO DISCUSSION NUMBER 30 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092013 500 PM AST TUE SEP 17 2013 HUMBERTO HAS NOT CHANGED MUCH SINCE THIS MORNING...AND IT STILL HAS SOME CHARACTERISTICS OF A SUBTROPICAL CYCLONE. THE ASSOCIATED DEEP CONVECTION IS ORGANIZED INTO A BROKEN BAND THAT EXTENDS ABOUT THREE-QUARTERS OF THE WAY AROUND THE CENTER. THE INITIAL WIND SPEED IS HELD AT 40 KT...WHICH IS A LITTLE HIGHER THAN THE DVORAK CLASSIFICATIONS. THE STORM IS LOCATED DIRECTLY BENEATH AN UPPER-LEVEL LOW...WHICH HAS ALLOWED THE SHEAR TO RELAX A LITTLE. THIS UPPER-LEVEL SYSTEM IS EXPECTED TO WEAKEN AND SHIFT EASTWARD DURING THE NEXT DAY OR TWO... AND HUMBERTO COULD LOSE SOME OF THE SUBTROPICAL CHARACTERISTICS WHILE THAT OCCURS. REGARDLESS...THE ATMOSPHERIC AND OCEANIC ENVIRONMENTS FAVOR SLIGHT STRENGTHENING DURING THE NEXT COUPLE OF DAYS...AND THE NHC INTENSITY FORECAST IS NUDGED UPWARD FROM THE PREVIOUS ONE...BUT IT LIES ON THE LOW SIDE OF THE GUIDANCE. HUMBERTO IS FORECAST TO BECOME EXTRATROPICAL IN 3 TO 4 DAYS... ALTHOUGH THERE IS SOME GUIDANCE THAT SHOWS THE CYCLONE DEGENERATING INTO A TROUGH BEFORE THAT OCCURS. HUMBERTO HAS BEEN MOVING NORTHWARD AT ABOUT 10 KT FOR THE PAST FEW HOURS. A SLOWER NORTH-NORTHWESTWARD TO NORTHWARD MOTION IS FORECAST DURING THE NEXT DAY OR SO. AFTER THAT TIME...THE SYSTEM IS EXPECTED TO ACCELERATE NORTHEASTWARD WHEN IT BECOMES EMBEDDDED IN THE STRONGER FLOW TO THE EAST OF AN APPROACHING DEEP-LAYER TROUGH. THE NHC TRACK FORECAST IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 30.3N 42.8W 40 KT 45 MPH 12H 18/0600Z 30.9N 43.3W 45 KT 50 MPH 24H 18/1800Z 32.0N 43.4W 45 KT 50 MPH 36H 19/0600Z 33.3N 43.2W 50 KT 60 MPH 48H 19/1800Z 35.0N 42.1W 50 KT 60 MPH 72H 20/1800Z 40.7N 37.2W 55 KT 65 MPH 96H 21/1800Z 51.5N 27.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 22/1800Z...DISSIPATED $$ FORECASTER CANGIALOSI NNNN