WTPZ44 KNHC 231435 RRA

TCDEP4



TROPICAL STORM HILARY DISCUSSION NUMBER   9

NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092017

1000 AM CDT SUN JUL 23 2017



VISIBLE IMAGERY INDICATES THAT HILARY IS BECOMING BETTER ORGANIZED.

A SMALL CENTRAL DENSE OVERCAST HAS FORMED, ALONG WITH A LARGE CURVED

BAND IN THE NORTHERN SEMICIRCLE OF THE CYCLONE. THE INITIAL WIND

SPEED IS SET TO 40 KT, A BLEND OF THE LATEST TAFB/SAB ESTIMATES.

HILARY COULD BE ON THE VERGE OF STARTING ITS LONG-ANTICIPATED

SIGNIFICANT STRENGTHENING PERIOD.  A 1059 UTC SSMIS MICROWAVE PASS

INDICATES MORE INNER-CORE STRUCTURE WITH THE STORM, WHICH SUGGESTS

THAT HILARY WILL BE ABLE TO TAKE ADVANTAGE OF THE NEARBY CONDUCIVE

ATMOSPHERIC AND OCEANIC CONDITIONS.  THE SHIPS GUIDANCE IS ALSO

INDICATING RELATIVELY HIGH CHANCES OF RAPID INTENSIFICATION, ROUGHLY

A 50/50 CHANCE DURING THE NEXT 48 HOURS. GIVEN THE FACTORS

ABOVE, THE NHC FORECAST IS RAISED FROM THE PREVIOUS ONE, BEST IN

LINE WITH A BLEND OF THE HWRF/DSHIP/HFIP CORRECTED CONSENSUS

MODELS.  AN INCREASE IN NORTHERLY SHEAR, POSSIBLY ENHANCED BY

OUTFLOW FROM TS IRWIN, SHOULD CAUSE SOME WEAKENING LATE IN THE

PERIOD, ALONG WITH MORE MARGINAL SSTS.



HILARY IS MOVING SLOWER NOW TO THE WEST-NORTHWEST AT ABOUT 9 KT. A

RIDGE OVER MEXICO SHOULD STEER HILARY IN THAT GENERAL DIRECTION FOR

THE NEXT SEVERAL DAYS, AT VARIOUS SPEEDS DUE TO THE STRENGTH OF THE

RIDGE.  LATER IN THE PERIOD, THERE IS A POSSIBILITY OF SOME BINARY

INTERACTION WITH IRWIN, WHICH ADDS SOME UNCERTAINTY TO THE FORECAST.

OVERALL, THERE HASN'T BEEN A LOT OF CHANGE TO THE MODEL GUIDANCE,

AND THE LATEST NHC TRACK PREDICTION STAYS RELATIVELY CLOSE TO THE