WTPZ45 KNHC 050836 RRA

TCDEP5



TROPICAL STORM IVETTE DISCUSSION NUMBER  11

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP102016

200 AM PDT FRI AUG 05 2016



THERE HAS BEEN LITTLE CHANGE IN THE CONVECTIVE ORGANIZATION OF

IVETTE OVERNIGHT.  THE LOW-LEVEL CENTER REMAINS EXPOSED TO THE

WEST AND NORTHWEST OF A LOOSELY CURVED BAND OF THUNDERSTORMS, DUE

TO WESTERLY TO NORTHWESTERLY SHEAR.  SUBJECTIVE AND OBJECTIVE

DVORAK T-NUMBERS ARE ALL NEAR T3.0, WHICH YIELDS AN INITIAL

WIND SPEED OF 45 KT.  ALTHOUGH THE SHEAR IS NOT VERY STRONG, IT

APPEARS THE SMALL SIZE OF THE CYCLONE AND PERHAPS SOME NEARBY DRY

MID-LEVEL AIR IN COMBINATION WITH THE SHEAR HAVE PREVENTED

INTENSIFICATION DURING THE PAST DAY.  THE GFS-BASED SHIPS GUIDANCE

INDICATES THAT THE SHEAR WILL DECREASE DURING THE NEXT 24 HOURS OR

SO, BUT THE ECMWF MODEL SHOWS A CONTINUATION OF SOME UPPER-LEVEL

WESTERLIES OVER IVETTE.  BECAUSE OF THESE DIFFERENCES IN THE

EXPECTED UPPER-LEVEL WINDS, THE NHC INTENSITY FORECAST IS MORE

UNCERTAIN THAN NORMAL.  THE UPDATED INTENSITY FORECAST CALLS FOR

SOME SLIGHT STRENGTHENING DURING THE NEXT 36 HOURS, BUT IT IS LOWER

THAN THE PREVIOUS ADVISORY, AND IT IS CLOSEST TO THE IVCN INTENSITY

CONSENSUS.  AFTER 48 H, INCREASING SOUTHWESTERLY SHEAR AND COOLER

SSTS SHOULD CAUSE A FAIRLY RAPID SPIN DOWN OF IVETTE, AND THE

CYCLONE IS LIKELY TO BECOME A REMNANT LOW IN 4 TO 5 DAYS.



THE TROPICAL STORM IS MOVING WESTWARD OR 275/12 KT.  IVETTE SHOULD

TURN WEST-NORTHWESTWARD IN 12 TO 24 HOURS AS A DEEPENING MID- TO

UPPER-LEVEL TROUGH TO THE NORTH OF THE HAWAIIAN ISLANDS WEAKENS THE

WESTERN PORTION OF THE SUBTROPICAL RIDGE.  AFTER DAY 3, IVETTE IS=