WTPZ45 KNHC 050245 RRA

TCDEP5



TROPICAL STORM IVETTE DISCUSSION NUMBER  10

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP102016

800 PM PDT THU AUG 04 2016



THOUGH IT MAY SOUND LIKE A BROKEN RECORD, IVETTE STILL IS

STRUGGLING TO INTENSIFY AND IS SHOWING THE DETRIMENTAL EFFECTS OF

VERTICAL SHEAR.  THE LOW-LEVEL CENTER APPEARS TO BE ON THE NORTHWEST

SIDE OF THE SMALL AREA OF COLD CLOUD TOPS, CONSISTENT WITH SOME

WEST-NORTHWESTERLY SHEAR AS SHOWN IN THE SHIPS DIAGNOSTICS AND THE

CIMSS ANALYSES.  YET, THE DEEP-LAYER VERTICAL SHEAR IS ONLY 5-10

KT, WHICH USUALLY IS CONDUCIVE FOR INTENSIFICATION.  PERHAPS IT IS

BECAUSE OF THE SMALL SIZE OF IVETTE - TROPICAL-STORM-FORCE WINDS

ONLY OUT TO 60 NM AT MOST - WHICH MAKES IT MORE SUSCEPTIBLE TO

RELATIVELY SMALL AMOUNTS OF SHEAR.  A BLEND OF THE TAFB, SAB, AND

CIMSS DVORAK CURRENT INTENSITY ESTIMATES GIVES 45 KT, WHICH IS

UNCHANGED FROM THE PREVIOUS ADVISORY. AN EARLIER ASCAT SCATTEROMETER

PASS CONFIRMED THE SMALL SIZE OF IVETTE.



IVETTE HAS ABOUT TWO DAYS LEFT TO INTENSIFY UNDER WHAT APPEAR TO BE

CONDUCIVE ENVIRONMENTAL CONDITIONS.  AFTER A COUPLE DAYS, THE SSTS

COOL AND THE LOW-LEVEL MOISTURE DECREASES, BUT STILL AT LEVELS THAT

COULD SUPPORT INTENSIFICATION.  BY DAYS FOUR AND FIVE, HOWEVER, THE

VERTICAL SHEAR SHOULD REACH AT LEAST 20 KT DUE TO AN UPPER-LEVEL

TROUGH APPROACHING IVETTE.  GRADUAL TO STEADY INTENSIFICATION IS

THUS EXPECTED TO ABOUT 36-48 HOURS WITH GRADUAL TO STEADY WEAKENING

THEREAFTER.  THE NHC INTENSITY FORECAST IS CLOSEST TO A BLEND OF THE

SHIPS STATISTICAL TECHNIQUE AND THE COAMPS REGIONAL DYNAMICAL MODEL

AND IS SLIGHTLY LESS THAN THAT PREDICTED IN THE PREVIOUS ADVISORY.=