WTPZ45 KNHC 132038 RRA

TCDEP5



HURRICANE DARBY DISCUSSION NUMBER   9

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP052016

300 PM MDT WED JUL 13 2016



DARBY IS TAKING ON A DIFFERENT SHAPE AS THE VERTICAL SHEAR GRADUALLY

DECREASES.  CONVECTIVE BURSTS WITH OVERSHOOTING TOPS HAVE BEEN

OCCURRING NEAR THE CENTER, AND A BROKEN BAND OF CONVECTION WRAPS

AROUND THE SOUTHERN AND WESTERN PART OF THE CIRCULATION. SUBJECTIVE

AND OBJECTIVE DVORAK ESTIMATES ARE UNANIMOUSLY T4.0, AND DARBY IS

THEREFORE BEING UPGRADED TO A 65-KT HURRICANE.  OCEAN TEMPERATURES

NEAR DARBY ARE BETWEEN 28-29 DEGREES CELSIUS, AND EVEN THOUGH SSTS

DECREASE SOME OUT AHEAD OF THE HURRICANE, MICROWAVE DATA SUGGEST

THAT THE OCEAN IS WARMING UP AFTER THE PASSAGES OF BLAS AND CELIA.

VERTICAL SHEAR IS ALSO EXPECTED TO BE LOW DURING THE NEXT FEW DAYS,

AND DARBY SHOULD CONTINUE STRENGTHENING FOR THE NEXT 36-48 HOURS.

THE NHC INTENSITY FORECAST IS NOT TOO DIFFERENT FROM THE PREVIOUS

FORECAST, AND IT IS NEAR OR JUST ABOVE THE UPPER BOUND OF THE

INTENSITY GUIDANCE.



THE LATEST FIXES INDICATE THAT DARBY IS BEGINNING TO GAIN LATITUDE

AGAIN, AND THE 12-HOUR AVERAGE MOTION IS 270/10 KT.  MID-LEVEL

RIDGING TO THE NORTH OF THE HURRICANE IS EXPECTED TO CHANGE VERY

LITTLE OVER THE NEXT FIVE DAYS, AND DARBY SHOULD THEREFORE MAINTAIN

A CONSISTENT WESTWARD TRACK THROUGH THE FORECAST PERIOD.  THE TRACK

GUIDANCE HAS SHIFTED A LITTLE TO THE NORTH ON THIS CYCLE, AND THERE

IS VERY LITTLE CROSS-TRACK DIFFERENCE NOTED AMONG THE MODELS.

HOWEVER, THERE ARE SOME ALONG-TRACK SPEED DIFFERENCES, WITH THE

ECMWF SHOWING A FASTER MOTION DUE TO A STRONGER DEPICTION OF THE

MID-LEVEL RIDGE.  THE UPDATED NHC TRACK FORECAST HAS BEEN NUDGED=