WTPZ41 KNHC 190847 RRA

TCDEP1



HURRICANE FERNANDA DISCUSSION NUMBER  30

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062017

200 AM PDT WED JUL 19 2017



FERNANDA'S CONVECTIVE CLOUD PATTERN HAS CONTINUED TO WITHER, AND

HAS BEEN ACCOMPANIED BY A GENERAL WARMING OF THE CLOUD TOPS. THE EYE

IS NO LONGER EVIDENT IN INFRARED IMAGERY AND A 0640Z AMSU OVERPASS

INDICATED THAT THE EYE HAD BECOME OPEN IN THE SOUTHERN SEMICIRCLE.

INTENSITY ESTIMATES ARE A CONSENSUS T4.5/77 KT FROM TAFB AND SAB,

ALONG WITH A RECENT CIRA-AMSU ESTIMATE OF 82 KT. A BLEND OF THESE

VALUES SUPPORTS LOWERING THE ADVISORY INTENSITY TO 80 KT.



THE INITIAL MOTION ESTIMATE REMAINS 310/08 KT. FERNANDA IS FORECAST

TO MOVE NORTHWESTWARD TODAY AND TURN TOWARD THE WEST-NORTHWEST BY

TONIGHT OR THURSDAY. A CONTINUATION OF THAT GENERAL MOTION IS

EXPECTED THROUGH THE END OF THE FORECAST PERIOD DUE TO A STRONG

SUBTROPICAL RIDGE REMAINING ENTRENCHED TO THE NORTH AND NORTHEAST OF

THE HAWAIIAN ISLANDS.  THE NEW NHC FORECAST TRACK IS ALMOST ON TOP

OF THE PREVIOUS ADVISORY TRACK, AND LIES CLOSE TO THE HFIP CORRECTED

CONSENSUS (HCCA) AND TVCN CONSENSUS MODELS.



FERNANDA IS EXPECTED TO STEADILY WEAKEN THROUGHOUT THE FORECAST

PERIOD. THE FIRST 36-48 HOURS OF WEAKENING WILL PRIMARILY BE DUE TO

THE CYCLONE MOVING OVER SUB-25C SSTS. FOLLOWING THAT WILL BE A

SHARP INCREASE IN SOUTHWESTERLY VERTICAL WIND SHEAR TO 25-30 KT,

CAUSING FERNANDA TO DEGENERATE INTO A POST-TROPICAL CYCLONE BY 72

HOURS. THE OFFICIAL INTENSITY FORECAST FOLLOWS THE DOWNWARD TREND OF

THE PREVIOUS ADVISORY AND IS SIMILAR TO THE ICON AND IVCN CONSENSUS

MODELS.



FORECAST POSITIONS AND MAX WINDS



INIT  19/0900Z 17.0N 135.0W   80 KT  90 MPH