WTPZ44 KNHC 280840 RRA

TCDEP4



TROPICAL STORM HILARY DISCUSSION NUMBER  28

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092017

200 AM PDT FRI JUL 28 2017



THE STRUCTURE OF HILARY HAS CHANGED LITTLE OVER THE PAST SEVERAL

HOURS, AS A SMALL AREA OF CONVECTION PERSISTS NEAR THE CENTER

MAINLY IN THE SOUTHEASTERN QUADRANT.  RECENT SATELLITE INTENSITY

ESTIMATES RANGE FROM 45-70 KT, AND BASED ON THESE, THE INITIAL

INTENSITY REMAINS A POSSIBLY GENEROUS 60 KT.



HILARY SHOULD CROSS THE 26C ISOTHERM IN 12-18 H, AND GIVEN THE

CURRENT LEVEL OF CONVECTIVE ORGANIZATION, SIGNIFICANT RE-

INTENSIFICATION SEEMS UNLIKELY DURING THAT TIME.  AFTER THAT, THE

CYCLONE IS FORECAST TO MOVE OVER STEADILY DECREASING SEA SURFACE

TEMPERATURES AND INTO A DRIER AIR MASS, AND THIS COMBINATION SHOULD

RESULT IN STEADY WEAKENING.  THE CYCLONE IS NOW FORECAST TO WEAKEN

TO A DEPRESSION IN ABOUT 72 H OVER 24C SEA SURFACE TEMPERATURES AND

DEGENERATE TO A REMNANT LOW SHORTLY THEREAFTER.  THE NEW INTENSITY

FORECAST SHOWS A FASTER WEAKENING THAN THE PREVIOUS FORECAST AFTER

12 H, AND IT IS IN BEST OVERALL AGREEMENT WITH THE SHIPS AND LGEM

MODELS.  IT IS POSSIBLE THAT INTERACTION WITH TROPICAL STORM IRWIN

COULD LEAD TO A FASTER DECAY THAN CURRENTLY FORECAST.



THE INITIAL MOTION IS 300/7, A LITTLE TO THE RIGHT OF THAT IN THE

PREVIOUS ADVISORY.  A MID-LEVEL RIDGE TO THE NORTH OF HILARY IS

EXPECTED TO STEER THE CYCLONE GENERALLY WEST-NORTHWESTWARD FOR 48 H

OR SO.  AROUND 72 H, A WESTWARD TURN APPEARS LIKELY AS THE CYCLONE

INTERACTS WITH, AND EVENTUALLY ABSORBS IRWIN.  AFTER THIS EVENT,

HILARY OR ITS REMNANTS SHOULD RESUME A WEST-NORTHWESTWARD MOTION AS