WTPZ44 KNHC 260249 RRA

TCDEP4



HURRICANE HILARY DISCUSSION NUMBER  19

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092017

900 PM MDT TUE JUL 25 2017



HILARY'S CONVECTIVE CLOUD PATTERN HAS CONTINUED TO FLUCTUATE

BETWEEN AN OCCASIONAL SYMMETRIC APPEARANCE CONTAINING A

CLOUD-COVERED EYE TO THE CURRENT ASYMMETRIC PATTERN WITH LITTLE

OR NO OUTER BANDING FEATURES EVIDENT AND THE EYE COMPLETELY

OBSCURED IN CONVENTIONAL INFRARED IMAGERY. HOWEVER, RECENT SSMI,

SSMIS, AND AMSU MICROWAVE IMAGES STILL INDICATE THAT HILARY HAS A

WELL-DEFINED, 10-NMI-DIAMETER EYE AND A THICK EYEWALL BENEATH THE

CIRRUS CANOPY. SATELLITE INTENSITY ESTIMATES RANGE FROM T4.5/77 KT

AND T5.0/90 KT FROM TAFB AND SAB, RESPECTIVELY, TO T5.5/102 KT FROM

THE NHC DVORAK OBJECTIVE TECHNIQUE. GIVEN THE LARGE RANGE OF

ESTIMATES, THE INITIAL INTENSITY WILL REMAIN AT 90 KT FOR NOW, WHICH

COULD BE A LITTLE CONSERVATIVE.



THE INITIAL MOTION REMAINS A STEADY 285/10 KT. HILARY IS FORECAST TO

CONTINUE ON A GENERAL WEST-NORTHWESTWARD TRACK FOR THE NEXT 72 HOURS

OR SO. THEREAFTER, A SLIGHT BEND TOWARD THE WEST WITH A DECREASE IN

FORWARD SPEED IS EXPECTED DUE TO BINARY/FUJIWHARA INTERACTION WITH

HURRICANE IRWIN. THE FORWARD SPEED DIFFERENCE BETWEEN HILARY AND

IRWIN IS ABOUT 3-4 KT, WITH HILARY STEADILY GETTING CLOSER TO IRWIN.

THAT TREND SHOULD CONTINUE ON DAYS 4 AND 5 WITH THE DISTANCE BETWEEN

THE TWO CYCLONES DECREASING TO ABOUT 300 NMI, RESULTING IN THE TWO

SYSTEMS ORBITING CYCLONICALLY ABOUT EACH OTHER. SINCE HILARY IS

FORECAST TO BE THE LARGER AND MORE DOMINANT CIRCULATION, IRWIN'S

EFFECT ON HILARY'S TRACK IS EXPECTED TO BE MINIMAL. THE LATEST NHC

MODEL GUIDANCE REMAINS TIGHTLY CLUSTERED AROUND THE PREVIOUS