WTPZ45 KNHC 171436 RRA

TCDEP5



HURRICANE DARBY DISCUSSION NUMBER  24

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016

800 AM PDT SUN JUL 17 2016



DARBY'S SATELLITE PRESENTATION HAS CHANGED VERY LITTLE SINCE THE

LAST ADVISORY.  THE HURRICANE STILL HAS A WELL-DEFINED 10 N MI WIDE

EYE AND A SYMMETRIC CENTRAL DENSE OVERCAST WITH CLOUD TOPS AS COLD

AS -68C.  THE INITIAL INTENSITY IS HELD AT 85 KT BASED ON A BLEND

OF THE LATEST DVORAK CURRENT INTENSITY NUMBERS, WHICH ARE 5.0/90 KT

FROM TAFB AND SAB AND 4.7/82 KT FROM THE UW-CIMSS ADT.



A NARROW SUBTROPICAL RIDGE LIES TO THE NORTH OF THE HURRICANE ALONG

30N, WHICH IS STEERING DARBY WESTWARD, OR 280/8 KT.  A WESTWARD OR

WEST-NORTHWESTWARD MOTION IS EXPECTED DURING THE NEXT FOUR DAYS DUE

TO THE POSITION AND STRENGTH OF THE RIDGE, AND THE TRACK GUIDANCE

IS IN EXCELLENT AGREEMENT DURING THIS PERIOD.  BY DAY 5, A WEAKER

DARBY IS FORECAST TO TURN WEST-SOUTHWESTWARD DUE TO STRONG

LOW-LEVEL RIDGING NORTH OF THE HAWAIIAN ISLANDS.  THERE IS A LITTLE

MORE SPREAD AMONG THE TRACK MODELS AT THE END OF THE FORECAST

PERIOD, BUT THE GFS, ECMWF, AND UKMET ARE ALL SOUTH OF THE TVCE

MULTI-MODEL CONSENSUS.  THE UPDATED FORECAST THEREFORE REMAINS

SOUTH OF TVCE AND IS A LITTLE FASTER THAN THE PREVIOUS FORECAST ON

DAY 5.



DARBY IS NOW OVER SSTS BETWEEN 24 AND 25C AND IS EXPECTED TO MOVE

OVER EVEN COLDER WATERS IN 12-24 HOURS.  THEREFORE, FAIRLY QUICK

WEAKENING IS FORECAST IN THE SHORT TERM, AND DARBY IS LIKELY TO LOSE

HURRICANE STRENGTH ON MONDAY.  SSTS ARE ACTUALLY EXPECTED TO BEGIN

INCREASING AGAIN AFTER 24 HOURS, WHICH COULD SLOW THE RATE OF

WEAKENING THROUGH THE END OF THE FORECAST PERIOD. HOWEVER,=