WTPZ44 KNHC 250858 RRA

TCDEP4



HURRICANE HILARY DISCUSSION NUMBER  16

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092017

300 AM MDT TUE JUL 25 2017



HILARY'S COMPACT, SYMMETRIC, INNER CORE CONTINUES TO BECOME BETTER

DEFINED ON SATELLITE IMAGERY.  MICROWAVE IMAGERY SUGGESTS

THAT THE EYE IS QUITE SMALL, LESS THAN 10 N MI IN DIAMETER, WITH

LITTLE EVIDENCE OF VERTICAL TILT OF THE VORTEX.  THE CURRENT

INTENSITY ESTIMATE IS NOW 90 KT IN AGREEMENT WITH A DVORAK ESTIMATE

FROM THE NESDIS SAB.  HILARY SHOULD BE IN A MOIST AIR MASS AND OVER

A WARM OCEAN FOR THE NEXT COUPLE OF DAYS.  DYNAMICAL GUIDANCE

PREDICTS SOME INCREASE IN NORTHERLY SHEAR OVER THE CYCLONE IN 1- TO

2-DAYS, BUT PROBABLY NOT ENOUGH OF AN INCREASE TO IMPEDE AT LEAST

SOME ADDITIONAL STRENGTHENING.  THE OFFICIAL INTENSITY FORECAST

CALLS FOR HILARY TO BECOME A MAJOR HURRICANE IN 12 HOURS OR SO AND

REACH A PEAK IN A DAY OR SO.  THIS IS IN GOOD AGREEMENT WITH THE

LATEST FLORIDA STATE UNIVERSITY SUPERENSEMBLE (FSSE) PREDICTION.

LATER IN THE FORECAST PERIOD, GRADUALLY COOLING SEA SURFACE

TEMPERATURES SHOULD INDUCE SLOW WEAKENING.



THE INITIAL MOTION ESTIMATE REMAINS WEST-NORTHWESTWARD, OR 290/9 KT.

A MID-TROPOSPHERIC RIDGE EXTENDING WESTWARD FROM THE SOUTHWESTERN

UNITED STATES WOULD CAUSE HILARY TO CONTINUE ON ITS

WEST-NORTHWESTWARD TRACK FOR THE NEXT SEVERAL DAYS.  IN A FEW DAYS,

HOWEVER, HILARY IS LIKELY TO PASS CLOSE TO HURRICANE IRWIN.  THE

CURRENT THINKING IS THAT THE CIRCULATION OF HILARY WILL DOMINATE SO

THAT LITTLE INFLUENCE ON HILARY'S TRACK, DUE TO BINARY INTERACTION

WITH IRWIN, WILL OCCUR.  ON THE OTHER HAND, THE LATTER TROPICAL

CYCLONE IS EXPECTED TO BEGIN ROTATING AROUND HILARY'S CIRCULATION