WTPZ44 KNHC 240250 RRA

TCDEP4



TROPICAL STORM HILARY DISCUSSION NUMBER  11

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092017

1000 PM CDT SUN JUL 23 2017



HILARY HAS CONTINUED TO BECOME BETTER ORGANIZED WITH A CURVED

CONVECTIVE BAND NOW WRAPPING NEARLY ALL THE WAY AROUND THE

LOW-LEVEL CENTER, AND A BANDING EYE OF ABOUT 10 N MI IN DIAMETER

EVIDENT IN RECENT SSMI/S MICROWAVE SATELLITE DATA. THE INTENSITY

ESTIMATE WAS 55 KT BY TAFB AT 0000Z, BUT SINCE THE OVERALL

CONVECTIVE AND INNER-CORE PATTERNS HAVE IMPROVED DURING THE PAST FEW

HOURS, THE INITIAL INTENSITY IS INCREASED TO 60 KT FOR THIS

ADVISORY.



THE INITIAL MOTION ESTIMATE IS 300/08 KT. THERE IS NO SIGNIFICANT

CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. HILARY IS

EXPECTED TO MOVE WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF

A DEEP-LAYER RIDGE TO ITS NORTH FOR THE NEXT SEVERAL DAYS, WITH A

SLIGHT INCREASE IN FORWARD SPEED EXPECTED IN ABOUT 48 HOURS OR SO.

THE NEW MODEL GUIDANCE IS TIGHTLY PACKED AROUND THE PREVIOUS

NHC ADVISORY TRACK THROUGH 96 H, SO THE NEW FORECAST TRACK IS JUST

AN UPDATE OF THE PREVIOUS ONE, AND CLOSELY FOLLOWS THE HCCA AND

TVCN MODELS.



GIVEN THE IMPROVING INNER-CORE STRUCTURE, COUPLED WITH VERY LOW

VERTICAL SHEAR VALUES AND A MOIST UNSTABLE ENVIRONMENT, CONTINUED

RAPID INTENSIFICATION APPEARS LIKELY FOR THE NEXT 36-48 HOURS WHILE

THE SMALL CYCLONE REMAINS OVER SSTS GREATER THAN 28C. BY 72 HOURS,

SSTS COOL TO NEAR 27C AND THE UPPER-OCEAN HEAT CONTENT DECREASES TO

LESS THAN 10 UNITS, SUGGESTING THAT COLD UPWELLING WILL PROBABLY

BEGIN AROUND THAT TIME. THE NEW INTENSITY FORECAST FOLLOWS THE

PREVIOUS ADVISORY BY SHOWING RAPID STRENGTHENING OF ABOUT 15 KT