WTPZ45 KNHC 031432 RRA

TCDEP5



TROPICAL STORM IVETTE DISCUSSION NUMBER   4

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP102016

800 AM PDT WED AUG 03 2016



IVETTE'S CONVECTIVE PATTERN IS GRADUALLY IMPROVING, WITH A BAND

LYING TO THE WEST OF A CENTRAL CLUSTER OF DEEP CONVECTION.

HOWEVER, RECENT MICROWAVE DATA STILL SHOWS THE LOW-LEVEL CENTER

DISPLACED TO THE NORTHEAST OF THE DEEPEST CONVECTION DUE TO SOME

SHEAR.  DVORAK INTENSITY ESTIMATES ARE T3.0/45 KT FROM SAB AND

T2.5/35 KT FROM TAFB. THE INITIAL INTENSITY IS THEREFORE RAISED TO

40 KT.



SEA SURFACE TEMPERATURES ARE EXPECTED TO BE 27-28C FOR THE NEXT

96 HOURS, WHILE THE VERTICAL SHEAR AFFECTING THE CYCLONE IS

FORECAST TO GRADUALLY DIMINISH OVER THE NEXT COUPLE OF DAYS.  THESE

CONDITIONS WOULD SEEM TO SUPPORT STEADY OR EVEN FAST STRENGTHENING.

SURPRISINGLY, THE SHIPS, LGEM, GFDL, AND HWRF MODELS ONLY INTENSIFY

IVETTE TO NEAR THE HURRICANE THRESHOLD.  GIVEN THE SEEMINGLY

FAVORABLE ENVIRONMENT, THE NHC OFFICIAL FORECAST IS ABOVE ALL OF THE

MAIN INTENSITY MODELS, WITH THE EXCEPTION OF COAMPS-TC, AND IT DOES

NOT DEVIATE FROM THE PEAK INTENSITY INDICATED IN THE PREVIOUS

ADVISORY.  SLIGHTLY LOWER SSTS AND INCREASING SHEAR ARE LIKELY TO

CAUSE SOME WEAKENING BY DAYS 4 AND 5.



A STRONG SUBTROPICAL RIDGE EXTENDING WESTWARD FROM NORTHERN MEXICO

IS CAUSING IVETTE TO MOVE QUICKLY WEST-NORTHWESTWARD AT 285/15 KT.

THE RIDGE IS EXPECTED TO REMAIN ENTRENCHED NORTH OF IVETTE FOR THE

NEXT THREE DAYS, PUTTING THE CYCLONE ON A WESTWARD HEADING BUT WITH

A GRADUALLY DECREASING FORWARD SPEED.  BY DAYS 4 AND 5, IVETTE

COULD GAIN A LITTLE MORE LATITUDE DUE TO A BREAK IN THE RIDGE THAT=