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Tropical Storm Walaka Discussion Number  27
NWS Central Pacific Hurricane Center Honolulu HI   CP012018
1100 PM HST Fri Oct 05 2018
 
The exposed low-level circulation center (LLCC) of Walaka has an
area of deep convection located about 60 n mi to the southeast. The
highest cloud tops within this area of towering cumulus clouds
and isolated thunderstorms is estimated to be about 37 
thousand feet. The swirl of low clouds associated with the LLCC
also appear to be less defined this evening according to the short
wave infrared imagery (that is, the so called "fog channel"). 
Since Walaka is likely undergoing extratropical transition at this
time, we will maintain its initial intensity at 40 kt for this
advisory.

The initial motion for this advisory is 045/15 kt. Walaka is being
steered by deep southwesterly flow ahead of an approaching
upper-level trough. This feature, and its associated surface front,
will also likely play a role in the future structure of Walaka once
it has completed its transition to an extratropical gale low. Due
to the strong southwesterly steering, Walaka will accelerate its
forward motion as it continues to move northeastward during the
next 24 to 36 hours. The latest track forecast has been adjusted
slightly to the left of the previous forecast package following a
blend of the GFS and ECMWF (operational runs and the ensemble 
means) track guidance.
 
Walaka will move over increasingly cooler water during the next 36
hours, but the baroclinic processes involved with its upcoming
extratropical phase will likely maintain an area of gale force winds
over the southeastern semicircle through 36 hours. The latest
intensity forecast has been adjusted up compared with the previous
advisory to account for these gales. The latest intensity forecast
follows a blend of the latest GFS and ECMWF guidance, which appear
to be in good agreement. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/0900Z 34.2N 165.1W   40 KT  45 MPH
 12H  06/1800Z 37.9N 162.2W   40 KT  45 MPH...POST-TROP/EXTRATROP
 24H  07/0600Z 44.0N 157.2W   35 KT  40 MPH...POST-TROP/EXTRATROP
 36H  07/1800Z 50.0N 151.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  08/0600Z...DISSIPATED
 
$$
Forecaster Houston
 
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