WTPZ45 KNHC 050851 RRA

TCDEP5



HURRICANE HECTOR DISCUSSION NUMBER  19

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP102018

200 AM PDT SUN AUG 05 2018



HECTOR HAS MAINTAINED A WELL-DEFINED, 10-NMI-DIAMETER EYE INSIDE A

GRADUALLY SHRINKING CENTRAL DENSE OVERCAST. SATELLITE INTENSITY

ESTIMATES AT 0600Z FROM TAFB AND SAB SUPPORTED AN INTENSITY OF 102

KT, WHILE UW-CIMSS ADT RAW ESTIMATES HAVE BEEN NEAR 100 KT. HOWEVER,

MORE RECENT INFRARED SATELLITE IMAGES INDICATE INTENSITY ESTIMATES

JUST BELOW 115 KT, SO THE ADVISORY INTENSITY OF 110 KT IS BASED ON

A BLEND OF THE AVAILABLE ESTIMATES WITH MORE WEIGHT PLACED ON

RECENT IR TRENDS.



THE INITIAL MOTION REMAINS 275/10 KT. A LARGE, DEEP-LAYER RIDGE TO

THE NORTH OF HECTOR IS EXPECTED TO STEER THE HURRICANE WESTWARD FOR

THE NEXT 24 H OR SO, FOLLOWED BY A MODEST POLEWARD 'STAIR-STEP' IN

THE TRACK THROUGH 72 H DUE TO A DISSIPATING FRONTAL TROUGH PUSHING

SOUTHWARD AND BECOMING STATIONARY NORTHEAST OF THE HAWAIIAN ISLANDS,

WHICH SHOULD WEAKEN THE LOW-LEVEL RIDGE.  AFTER THAT TIME, HOWEVER,

THE SURFACE TROUGH IS FORECAST TO WEAKEN, ALLOWING THE RIDGE TO

BUILD BACK ACROSS THE ISLANDS, FORCING HECTOR BACK ONTO A MORE

WESTERLY COURSE ON DAYS 4 AND 5. MORE WEAKENING OF THE RIDGE IN

48-72 HOURS HAS RESULTED IN YET ANOTHER NORTHWARD SHIFT IN THE

GUIDANCE ENVELOPE, WITH THE HWRF AND HMON MODELS BRINGING HECTOR

WITHIN 60 NMI OF THE BIG ISLAND ON DAY 4. THE NEW NHC FORECAST TRACK

HAS BEEN SHIFTED SLIGHTLY NORTHWARD AS A RESULT, BUT LIES JUST A TAD

SOUTH OF THE CONSENSUS MODELS OUT OF RESPECT FOR THE RELIABLE ECMWF

MODEL, WHICH IS THE SOUTHERNMOST OF ALL OF THE GLOBAL AND REGIONAL