WTPA42 PHFO 292054 RRA

TCDCP2



TROPICAL STORM ULIKA DISCUSSION NUMBER  14

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP192016

1100 AM HST THU SEP 29 2016



AFTER A BURST OF DEEP CONVECTION THAT PERSISTED NEAR THE

CENTER OF ULIKA FOR MOST OF THE NIGHT, VISIBLE SATELLITE IMAGERY

INDICATES THAT THE LOW-LEVEL CIRCULATION CENTER OF ULIKA IS NOW

EXPOSED TO THE SOUTHWEST OF AN AREA OF WANING DEEP CONVECTION.

MEANWHILE, WATER VAPOR IMAGERY SHOWS THAT ULIKA IS EMBEDDED IN A

HOSTILE ENVIRONMENT ALOFT, WITH A MID-LEVEL LOW CENTERED TO ITS

NORTHWEST SUPPLYING OVER 30 KT OF VERTICAL WIND SHEAR. A

CONSERVATIVE BLEND OF THE SUBJECTIVE DVORAK CURRENT INTENSITY

ESTIMATES OF 1.5/25 KT FROM GTW, 2.0/30 KT FROM HFO AND SAB, AND THE

ADT ESTIMATE OF 2.9/43 KT FROM UW-CIMSS YIELDED AN INITIAL INTENSITY

ESTIMATE OF 35 KT FOR THIS CYCLE. THIS WAS SUBSEQUENTLY CONFIRMED BY

AN 1858Z ASCAT PASS THAT DETECTED 35 KT IN THE NORTH AND NORTHEAST

SEMICIRCLES.



THE INITIAL MOTION ESTIMATE FOR THIS ADVISORY IS 305/07 KT, WITH

ULIKA BEING STEERED TOWARD THE NORTHWEST BY THE FLOW AROUND THE

NEARBY MID-LEVEL LOW. THIS FEATURE WILL LIKELY PROHIBIT DEEP

CONVECTION FROM RE-DEVELOPING OVER THE CENTER AS ASSOCIATED SHEAR IS

FORECAST TO STEADILY INCREASE TO NEAR 60 KT OVER THE NEXT 2 DAYS.

THIS WILL CAUSE THE CYCLONE TO BECOME INCREASINGLY SHALLOW OVER THE

NEXT 12 TO 24 HOURS, WITH SPIN-DOWN TO A REMNANT LOW EXPECTED TO

OCCUR SOON. THE SHALLOW CYCLONE IS THEN FORECAST TO MOVE TOWARD THE

WEST (UNTIL DISSIPATION OCCURS) WITHIN THE LOW-LEVEL TRADE WIND FLOW

SUPPORTED BY A SURFACE HIGH FAR TO THE NORTH. THE UPDATED OFFICIAL

TRACK FORECAST PARALLELS THE PREVIOUS, BUT IS SHIFTED TO THE RIGHT