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#633149 (Received by flhurricane at: 10:56 PM 18.Sep.2013) TCDAT4 TROPICAL DEPRESSION HUMBERTO DISCUSSION NUMBER 35 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092013 1100 PM AST WED SEP 18 2013 HUMBERTO IS LOSING ORGANIZATION THIS EVENING. SHORTWAVE-IR IMAGERY INDICATES THAT THE LOW-LEVEL CIRCULATION HAS BECOME STRETCHED FROM THE NORTHWEST TO SOUTHEAST...WITH LITTLE CONVECTION REMAINING. THE INITIAL INTENSITY IS LOWERED TO 30 KT IN AGREEMENT WITH THE LATEST TAFB SATELLITE ESTIMATE. WHILE THE CYCLONE STILL HAS SOME TIME OVER MARGINAL SSTS AND IN LIGHT/MODERATE SHEAR...THE POOR INITIAL STRUCTURE WILL LIKELY PREVENT HUMBERTO FROM SIGNIFICANT STRENGTHENING IN THE SHORT TERM. AFTER 24H...THE SYSTEM SHOULD ACCELERATE TO THE NORTHEAST...AND MOST OF THE GUIDANCE SHOW SOME INCREASE IN STRENGTH DURING EXTRATROPICAL TRANSITION. AFTER ACCOUNTING FOR THE WEAKER INITIAL WINDS...THE LATEST NHC FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE. SINCE THE CIRCULATION HAS BECOME ELONGATED...THE INITIAL MOTION ESTIMATE IS A VERY UNCERTAIN 010/8. GUIDANCE REMAINS IN GOOD AGREEMENT ON HUMBERTO TURNING TO THE NORTHEAST AND ACCELERATING AHEAD OF A MID-LATITUDE TROUGH. THE OFFICIAL FORECAST IS NUDGED A LITTLE TO THE EAST CLOSER TO THE MODEL CONSENSUS. GLOBAL MODELS SUGGEST THE CYCLONE WILL DISSIPATE OR BE ABSORBED WITHIN A LARGER EXTRATROPICAL LOW BY 72H. THE NHC PREDICTION WILL GO ALONG WITH THE ABSORBED SCENARIO...THOUGH IT WOULD NOT BE SURPRISING IF HUMBERTO OPENED UP INTO A TROUGH BEFORE THAT TIME. FORECAST POSITIONS AND MAX WINDS INIT 19/0300Z 32.5N 43.4W 30 KT 35 MPH 12H 19/1200Z 33.7N 43.0W 30 KT 35 MPH 24H 20/0000Z 35.7N 41.6W 30 KT 35 MPH 36H 20/1200Z 38.6N 38.8W 35 KT 40 MPH 48H 21/0000Z 43.0N 34.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 22/0000Z...ABSORBED $$ FORECASTER BLAKE |