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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
closely follows the previous, and most closely follows the GFEX
model blend. Trends presented by SHIPS/LGEM were closely followed
for the intensity forecast, while HWFI/GHMI (and therefore IVCN)
were disregarded due to an unrealistic intensification trend
indicated on days 2 and 3. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/0300Z 17.7N 141.0W   35 KT  40 MPH
 12H  30/1200Z 18.3N 142.3W   30 KT  35 MPH
 24H  01/0000Z 18.6N 144.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  01/1200Z 18.6N 146.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  02/0000Z 18.6N 149.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  03/0000Z...DISSIPATED
 
$$
Forecaster Birchard
 
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