WTPZ41 KNHC 182038 RRA

TCDEP1



HURRICANE FERNANDA DISCUSSION NUMBER  28

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062017

200 PM PDT TUE JUL 18 2017



SOMEWHAT SURPRISINGLY, FERNANDA HAS MADE A SMALL COMEBACK THIS

AFTERNOON AS ITS EYE HAS BECOME DISTINCT IN THE VISIBLE SATELLITE

IMAGERY IN THE MIDST OF A RAGGED RING OF VERY COLD CLOUD TOPS.

SUBJECTIVE DVORAK CLASSIFICATIONS FROM SAB AND TAFB AND THE

OBJECTIVE ADT HAVE INCREASED SOME, SO AN INITIAL INTENSITY OF 90

KT IS ANALYZED.



THE HURRICANE IS MOVING TOWARD THE NORTHWEST AT 7 KT.  FERNANDA'S

MOTION IS BEING INFLUENCED BY A DEEP-LAYER SUBTROPICAL RIDGE TO ITS

NORTHEAST AND A MID-LEVEL TROUGH TO ITS NORTHWEST.  IN A COUPLE OF

DAYS, THE TROUGH LIFTS OUT AND A MID-LEVEL RIDGE BUILDS IN NORTH OF

FERNANDA CAUSING THE TROPICAL CYCLONE TO TURN BACK TOWARD THE

WEST-NORTHWEST OR WEST.  THE TRACK GUIDANCE IS TIGHTLY CLUSTERED FOR

THE FIRST COUPLE OF DAYS BUT AT THE EXTENDED RANGE THE GUIDANCE

SHOWS MORE SPREAD, ESPECIALLY ALONG THE TRACK.  THE OFFICIAL TRACK

FORECAST IS BASED UPON THE TVCN MULTI-MODEL TRACK CONSENSUS AND IS

NEARLY IDENTICAL TO THE PREVIOUS ADVISORY.



FERNANDA IS EXPECTED TO STEADILY WEAKEN DURING THE NEXT COUPLE OF

DAYS AS IT INGESTS STABLE, DRY AIR OVER INCREASINGLY COOLER SSTS.

IN TWO TO THREE DAYS, SOUTHWESTERLY VERTICAL SHEAR SHOULD

SUBSTANTIALLY INCREASE AND FURTHER CONTRIBUTE TO FERNANDA'S

WEAKENING.  BY DAYS 4 AND 5, THE WINDS FROM FERNANDA MAY BE

AUGMENTED SOME BY A STRONG PRESSURE GRADIENT SETTING UP NORTH OF THE

TROPICAL CYCLONE.  THE OFFICIAL INTENSITY FORECAST - NEARLY THE SAME

AS FROM THE PREVIOUS ADVISORY - IS BASED UPON THE IVCN MULTI-MODEL