ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM HURRICANE HUMBERTO DISCUSSION NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092013 1100 AM AST THU SEP 12 2013 ALTHOUGH THERE IS SOME EVIDENCE OF SOUTH-SOUTHWESTERLY SHEAR OVER THE SYSTEM...HUMBERTO REMAINS FAIRLY WELL ORGANIZED WITH CONTINUED HINTS OF A BANDING-TYPE EYE. DVORAK CLASSIFICATIONS FROM TAFB AND SAB CONTINUE TO SUPPORT AN INTENSITY OF 75 KT FOR THIS ADVISORY. INCREASING WEST-SOUTHWESTERLY SHEAR AND COOL SEA SURFACE TEMPERATURES SHOULD CAUSE WEAKENING OVER THE NEXT COUPLE OF DAYS. LATER IN THE PERIOD...ALTHOUGH HUMBERTO IS FORECAST TO TRAVERSE THE WARMER WATERS WEST OF 40W LONGITUDE...THE SHEAR IS LIKELY TO REMAIN STRONG...SO RESTRENGTHENING IS NOT ANTICIPATED AT THIS TIME. THE OFFICIAL WIND SPEED FORECAST IS NEAR THE LOW END OF THE NUMERICAL GUIDANCE AND LIES BETWEEN THE LATEST DSHIPS AND LGEM PREDICTIONS. THE HURRICANE IS MOVING NORTHWARD AT A SLIGHTLY FASTER PACE...OR 360/13. A LARGE MID-LEVEL HIGH PRESSURE SYSTEM CENTERED NORTH OF THE AZORES SHOULD CAUSE HUMBERTO TO TURN TOWARD THE NORTHWEST AND WEST-NORTHWEST DURING THE FORECAST PERIOD. LATE IN THE PERIOD...GLOBAL MODELS PREDICT A WEAKENING OF THE HIGH WHILE A MID-LEVEL TROUGH MOVES EASTWARD FROM ATLANTIC CANADA AND THE NORTHEASTERN UNITED STATES. BY THIS TIME...THE TROPICAL CYCLONE IS EXPECTED TO SLOW ITS FORWARD SPEED DUE TO A WEAKENING STEERING CURRENT. THE TRACK GUIDANCE HAS ONCE AGAIN SHIFTED TO THE RIGHT... AND THE OFFICIAL FORECAST IS ADJUSTED IN THAT DIRECTION. THIS IS VERY CLOSE TO THE LATEST MULTI-MODEL CONSENSUS. A RECENT ASCAT OVER PASS REVEALED A SIGNIFICANTLY LARGER HURRICANE THAN PREVIOUS ESTIMATED...AND THE WIND RADII HAVE BEEN EXPANDED ACCORDINGLY. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 21.8N 29.0W 75 KT 85 MPH 12H 13/0000Z 23.3N 29.8W 70 KT 80 MPH 24H 13/1200Z 24.6N 31.2W 65 KT 75 MPH 36H 14/0000Z 25.4N 33.0W 55 KT 65 MPH 48H 14/1200Z 26.0N 35.0W 45 KT 50 MPH 72H 15/1200Z 27.5N 39.5W 40 KT 45 MPH 96H 16/1200Z 29.0N 43.0W 35 KT 40 MPH 120H 17/1200Z 31.0N 45.0W 35 KT 40 MPH $$ FORECASTER PASCH NNNN