WTPZ41 KNHC 012054 RRA

TCDEP1



HURRICANE NORMAN DISCUSSION NUMBER  19

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP162018

200 PM PDT SAT SEP 01 2018



SINCE THE PREVIOUS ADVISORY, A WELL-DEFINED CLOSED EYE HAS REMAINED

APPARENT IN MICROWAVE SATELLITE DATA, AND A CLOUD-FILLED EYE HAS

APPEARED IN VISIBLE SATELLITE IMAGERY DURING THE PAST COUPLE OF

HOURS. SATELLITE INTENSITY ESTIMATED HAVEN'T CHANGED SINCE THE

PREVIOUS ADVISORY, SO THE INITIAL INTENSITY REMAINS 90 KT, WHICH IS

SUPPORTED BY A 1501Z SATCON ESTIMATE OF 88 KT AND A DVORAK CI VALUE

OF T5.0/90 KT.



NORMAN'S INITIAL MOTION ESTIMATE IS NOW 275/12 KT BASED ON MICROWAVE

AND VISIBLE SATELLITE EYE POSITION ESTIMATES. THERE ARE

NO SIGNIFICANT CHANGES TO THE PREVIOUS TRACK FORECAST AND REASONING.

THE HURRICANE IS EXPECTED TO BE STEERED BY A STRONG DEEP-LAYER

SUBTROPICAL RIDGE TO THE NORTH, RESULTING IN A WESTWARD MOTION FOR

THE NEXT 12-24 HOURS, FOLLOWED BY A WEST-NORTHWESTWARD MOTION AT A

FASTER FORWARD SPEED. THE LATEST MODEL GUIDANCE IS TIGHTLY PACKED

ABOUT THE PREVIOUS FORECAST TRACK THROUGH 96 HOURS, WITH MUCH LESS

DIVERGENCE AFTER THAT COMPARED TO PREVIOUS MODEL RUNS. THEREFORE,

THE NEW FORECAST TRACK IS ESSENTIALLY JUST AN EXTENSION OF THE

PREVIOUS ADVISORY TRACK, AND LIES CLOSE TO A BLEND OF THE HCCA,

FSSE, AND TVCE CONSENSUS TRACK MODELS.



THE GFS AND ECMWF MODELS ARE FORECASTING THE 15-20 KT OF VERTICAL

WIND SHEAR THAT HAS BEEN AFFECTING NORMAN TO STEADILY DECREASE FOR

THE NEXT 60-72 HOURS, POSSIBLY BECOMING NEAR ZERO IF THE ECMWF

UPPER-LEVEL WIND FORECASTS VERIFY. SINCE THE HURRICANE IS EXPECTED

TO REMAIN OVER 27 DEG C AND WARMER SSTS FOR THE NEXT 48 HOURS, ONLY