WTPA42 PHFO 300239 RRA

TCDCP2



TROPICAL STORM ULIKA DISCUSSION NUMBER  15

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP192016

500 PM HST THU SEP 29 2016



THE WELL-DEFINED LOW-LEVEL CIRCULATION CENTER OF ULIKA HAS BEEN

EXPOSED TO THE SOUTH AND SOUTHWEST OF LIMITED DEEP CONVECTION FOR

MOST OF THE TIME SINCE THE PREVIOUS ADVISORY, BUT MODEST NEW

CONVECTION HAS MORE RECENTLY DEVELOPED CLOSE TO THE CENTER, DESPITE

STRONG WESTERLY SHEAR ON THE ORDER OF 30-40 KT. SUBJECTIVE DVORAK

CURRENT INTENSITY ESTIMATES HAVE BEEN TRENDING LOWER, AND RANGE FROM

TOO WEAK TO CLASSIFY FROM SAB TO 1.5/25 KT FROM HFO/GTW, WHILE ADT

HAS DIMINISHED TO 2.2/32 KT. THE INITIAL INTENSITY OF 35 KT USED FOR

THIS ADVISORY IS PRIMARILY BASED ON A PAIR OF MID-MORNING ASCAT

PASSES THAT INDICATED WINDS OF AT LEAST 35 KT, AND THE FACT THAT THE

SATELLITE PRESENTATION HAS CHANGED LITTLE SINCE.



THE INITIAL MOTION ESTIMATE FOR THIS ADVISORY IS 305/09 KT, WITH

ULIKA BEING STEERED TOWARD THE NORTHWEST BY THE COUNTER-

CLOCKWISE FLOW AROUND A MID-LEVEL LOW CENTERED TO THE NORTHWEST.

ALTHOUGH ISOLATED SMALL THUNDERSTORM CELLS HAVE BRIEFLY DEVELOPED

NEAR THE CENTER OF ULIKA THIS AFTERNOON, PERSISTENT DEEP CONVECTION

IS NOT EXPECTED OVER THE CENTER AS SHEAR IS FORECAST TO FURTHER

INCREASE THE NEXT 2 DAYS. THE CYCLONE IS THEREFORE EXPECTED TO

BECOME INCREASINGLY SHALLOW OVER THE NEXT 12 TO 24 HOURS, AND

SPIN-DOWN TO A REMNANT LOW IS EXPECTED TO OCCUR SOON.



AS THE SYSTEM WEAKENS, THE PRIMARY STEERING MECHANISM WILL BECOME A

SURFACE HIGH FAR TO THE NORTH, WHICH WILL DRIVE THE SYSTEM TOWARD

THE WEST UNTIL DISSIPATION OCCURS. THE OFFICIAL TRACK FORECAST=