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Post-Tropical Cyclone Akoni Forecast Discussion


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000
WTPA43 PHFO 061444
TCDCP3

Post-Tropical Cyclone Akoni Discussion Number  10
NWS Central Pacific Hurricane Center Honolulu HI   EP122019
500 AM HST Fri Sep 06 2019

Although showers and thunderstorms continue to pulse near Akoni's 
elongated low-level circulation center (LLCC), they have not
been sufficiently persistent or organized to continue to classify
the system as a tropical cyclone, and Akoni is being downgraded to
a post-tropical remnant low. An overnight ASCAT-C pass showed 
southerly winds to 30 kt in an area east of the center, and that 
will be the initial intensity for this advisory. 

The initial motion estimate is a very uncertain 270/14 kt, as it 
appears that the LLCC has re-formed west of its previous location.
A low- to mid-level ridge will strengthen far north of the remnant
low over the next couple of days, and the associated gradient
will likely support 30 kt winds in the northern semicircle. The
high will also drive the system toward the west to west-northwest,
with an increase in forward speed expected over the weekend. Little
change in strength is expected until the system encounters increased
vertical wind shear toward the latter part of the forecast period.
This is expected to cause the low to weaken and open into a trough
by day 4 or 5, similar to the solutions presented by GFS and ECMWF
guidance.  

This is the last advisory issued by the Central Pacific Hurricane 
Center on this system, unless regeneration occurs. For additional 
information on the remnant low, please see High Seas Forecasts 
issued by the National Weather Service Honolulu, under AWIPS header 
HFOHSFNP, WMO header FZPN40 PHFO, and available on the Web at 
weather.gov/hfo/HSFNP.


FORECAST POSITIONS AND MAX WINDS

INIT  06/1500Z 11.2N 149.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 12H  07/0000Z 11.2N 151.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
 24H  07/1200Z 11.4N 153.7W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  08/0000Z 12.0N 156.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  08/1200Z 12.9N 159.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  09/1200Z 15.0N 166.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  10/1200Z 17.0N 172.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  11/1200Z...DISSIPATED

$$
Forecaster Birchard