WTPZ41 KNHC 030238 RRA

TCDEP1



HURRICANE SERGIO DISCUSSION NUMBER  15

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP212018

800 PM PDT TUE OCT 02 2018



THE EYE OF SERGIO HAS BECOME OBSCURED OVER THE PAST SEVERAL HOURS,

INDICATING THAT THE INTENSIFYING TREND HAS LEVELLED OFF.  IT

APPEARS THAT NORTHEASTERLY SHEAR IS AFFECTING THE INNER CORE AS THE

LATEST MICROWAVE DATA INDICATE AN OPEN EYEWALL ON THE NORTHERN SIDE

OF THE HURRICANE.  THE INTENSITY IS HELD AT 100 KT FOR THIS

ADVISORY SINCE THE OVERALL WIND SPEED ESTIMATES HAVEN'T CHANGED

MUCH, ALTHOUGH THERE IS A FAIR SPREAD IN THOSE VALUES.  THE SHEAR

IS FORECAST TO DECREASE OVER THE NEXT DAY OR TWO, WHICH SHOULD

ALLOW FURTHER STRENGTHENING OF SERGIO, PENDING ANY EYEWALL CYCLES.

WEAKENING IS EXPECTED IN THE LONGER RANGE WHILE THE HURRICANE MOVES

OVER MORE SHALLOW MARGINALLY WARM WATERS.  ONLY A SMALL CHANGE HAS

BEEN MADE TO THE SHORT TERM INTENSITY FORECAST, AND THE REST OF THE

FORECAST IS ESSENTIALLY THE SAME.



SERGIO HAS TURNED TOWARD THE WEST-NORTHWEST AND SLOWED DOWN, AS

FORECAST, NOW 300/9.   A WEST-NORTHWEST OR NORTHWEST TRACK IS

EXPECTED AS A RIDGE WEAKENS TO THE NORTH OF SERGIO FOR THE NEXT DAY

OR TWO.  THEREAFTER, A STRONG RIDGE IS FORECAST TO BUILD TO THE

NORTHWEST OF SERGIO, WHICH SHOULD FORCE A WESTWARD MOTION.  AS HAS

BEEN THE CASE FOR MANY CYCLONES THIS SEASON, THE GFS-BASED GUIDANCE

IS ON THE RIGHT SIDE OF TRACK GUIDANCE ENVELOPE, WHILE THE

ECMWF/UKMET ARE ON THE LEFT SIDE.  THE CONSENSUS HAS REMAINED QUITE

STEADY NEAR THE PREVIOUS INTERPOLATED OFFICIAL FORECAST, THUS

THE NEW FORECAST IS BASICALLY JUST AN UPDATE OF THE PREVIOUS ONE.





FORECAST POSITIONS AND MAX WINDS