WTPZ45 KNHC 070233 RRA

TCDEP5



TROPICAL STORM IVETTE DISCUSSION NUMBER  18

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP102016

800 PM PDT SAT AUG 06 2016



VISIBLE AND INFRARED SATELLITE IMAGERY INDICATE THAT ALL OF IVETTE'S

DEEP CONVECTION HAS BEEN SHEARED AWAY BY MODERATE-TO-STRONG

SOUTHWESTERLY VERTICAL WIND SHEAR, LEAVING THE LOW-LEVEL CIRCULATION

CENTER FULLY EXPOSED MORE THAN 80 N MI SOUTHWEST OF ANY CONVECTION.

SATELLITE INTENSITY ESTIMATE FROM TAFB AND SAB HAVE DECREASED AS A

RESULT, AND THE LATEST UW-CIMSS INTENSITY ESTIMATE IS T2.7/39 KT.

ALLOWING FOR SOME VORTEX SPIN DOWN SINCE THE PREVIOUS ADVISORY

INTENSITY OF 45 KT, THE INITIAL INTENSITY HAS BEEN LOWERED TO 40 KT

FOR THIS ADVISORY.



IVETTE HAS CONTINUED TO MOVE WEST-NORTHWESTWARD, OR 290/10 KT.  THIS

GENERAL MOTION SHOULD CONTINUE FOR THE NEXT 36 HOURS OR SO WHILE THE

CYCLONE MOVES TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE AROUND

139W-140W LONGITUDE. AFTER THAT TIME, HOWEVER, IVETTE IS EXPECTED TO

BE A VERTICALLY SHALLOW REMNANT LOW PRESSURE SYSTEM THAT WILL BE

STEERED WESTWARD AND THEN WEST-SOUTHWESTWARD BY THE LOW-LEVEL

TRADEWIND FLOW. THE NEW NHC TRACK FORECAST IS ESSENTIALLY JUST AN

EXTENSION OF THE PREVIOUS ADVISORY TRACK AND LIES A LITTLE SOUTH OF

THE MULTI-MODEL CONSENSUS TVCN DUE TO MORE RAPID WEAKENING THAN

PREVIOUSLY EXPECTED.



IVETTE STILL HAS A VERY ROBUST LOW-LEVEL CIRCULATION AND IS MOVING

OVER NEAR-28C SSTS, SO REDEVELOPMENT OF DEEP CONVECTION SEEMS LIKELY

TONIGHT AFTER 0600Z DURING THE CONVECTIVE MAXIMUM PERIOD, WHICH

SHOULD ALLOW THE CYCLONE TO RETAIN TROPICAL STORM STATUS. HOWEVER,

BY 24 HOURS AND BEYOND, STRONG SOUTHWESTERLY SHEAR OF 25 KT OR MORE,=