WTPZ44 KNHC 271435 RRA

TCDEP4



HURRICANE HILARY DISCUSSION NUMBER  25

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092017

800 AM PDT THU JUL 27 2017



HILARY REMAINS SOMEWHAT SHEARED, AND SHORTWAVE IR IMAGERY

SUGGESTS THAT MUCH OF THE WESTERN SEMICIRCLE OF THE CIRCULATION HAS

EXPOSED THIS MORNING.  THE INTENSITY HAS BEEN LOWERED TO 70 KT BASED

ON A BLEND OF FINAL-T AND CURRENT INTENSITY (CI) VALUES FROM TAFB

AND SAB, AND THE CI FROM THE UW-CIMSS ADT.



THE INTENSITY FORECAST IS DEFINED BY A SPLIT IN THE DYNAMICAL AND

STATISTICAL GUIDANCE.  THE DYNAMICAL COAMPS-TC AND HWRF MODELS SHOW

A BRIEF PERIOD OF RE-INTENSIFICATION DUE TO A DECREASE IN SHEAR

THAT ALLOWS CONVECTION TO RE-WRAP AROUND THE CIRCULATION.  ON THE

OTHER HAND, THE STATISTICAL MODELS SHOW GRADUAL WEAKENING

THROUGHOUT THE FORECAST PERIOD.  FOR THE FIRST 36 H, THE NHC

FORECAST SPLITS THE DIFFERENCE BETWEEN THESE SCENARIOS.  AFTER THAT

TIME, QUICKLY DROPPING SSTS ALONG THE FORECAST TRACK SHOULD LEAD TO

STEADY WEAKENING.  BY 120 H, HILARY IS SHOWN TO BE A REMNANT LOW,

AND IS EXPECTED TO HAVE ABSORBED THE CIRCULATION OF IRWIN, WHICH IS

FORECAST TO MOVE WITHIN JUST A FEW DEGREES OF HILARY BY DAY 4.

OVERALL, THE NEW OFFICIAL FORECAST IS A LITTLE LOWER THAN THE

PREVIOUS ADVISORY.



ALTHOUGH THE TRACK FORECAST REMAINS COMPLICATED DUE TO THE IMMINENT

INTERACTION OF HILARY AND IRWIN, VERY LITTLE CHANGE HAS BEEN MADE

TO THE FORECAST TRACK.  A MID-LEVEL RIDGE EXTENDING FROM THE

SOUTHWESTERN U.S. WILL KEEP HILARY MOVING GENERALLY WEST-NORTHWEST

OR NORTHWESTWARD FOR A DAY OR TWO.  THE RIDGE WEAKENS A LITTLE

AFTER THAT, BUT THE APPROACH OF IRWIN SHOULD AFFECT THE TRACK OF