WTPA41 PHFO 012107

TCDCP1



Hurricane Walaka Discussion Number   9

NWS Central Pacific Hurricane Center Honolulu HI   CP012018

1100 AM HST Mon Oct 01 2018



Hurricane Walaka is an impressive tropical cyclone. A 20 nm wide

clear eye is surrounded by a large ring of -70 to -76C cloud tops

with excellent upper level outflow in all quadrants. Banding

features are also present though not as well-formed as early

this morning. Intensity estimates came in at 6.0/115 kt from PHFO

and JTWC, and 6.5/127 kt from SAB. ADT was 6.7/132 kt at 1800 UTC.

Given the overall appearance and intensification trend, the initial

intensity for this advisory leans on the higher end of the estimates

at 130 kt.



Walaka is moving at 305/9 kt as it rounds the southwestern flank of

a subtropical ridge. A developing low pressure system is expected to

produce a break in the ridge to the north of the hurricane and cause

a turn toward the north on Tuesday. The numerical models are in

agreement with the scenario and the track guidance is tightly

packed, especially through 72 hours. Walaka is expected to

accelerate toward the north under the influence of the low on

Wednesday and into Thursday. The forecast track for this advisory is

essentially a refresh of the previous forecast and is close to the

HCCA consensus, especially through 72 hours.



Rapid intensification has been occurring since last night. With sea

surface temperatures under Walaka expected to remain near 30C

through tonight, high ocean heat content, and low vertical wind

shear, there is no reason to believe that peak intensity has been

reached. SHIPS forecasts 147 kt from 18 to 24 hours so the forecast

calls for a peak intensity of 145 kt tonight before starting a

weakening trend. This will put Walaka in Category 5 territory on

the Saffir-Simpson scale and exceeds the maximum intensity achieved

by Hurricane Ioke in 2006.



The forecast track will take Walaka near Johnston Island on Tuesday

and the Hurricane Warning remains in effect for this location. The

northeastward track after Tuesday is also expected to take the

hurricane across the Papahanaumokuakea Marine National Monument

between French Frigate Shoals and Laysan Island on Thursday, and a

Hurricane Watch may be needed for these locations later today or

tonight.





FORECAST POSITIONS AND MAX WINDS



INIT  01/2100Z 12.9N 169.3W  130 KT 150 MPH

 12H  02/0600Z 14.0N 170.1W  140 KT 160 MPH

 24H  02/1800Z 15.6N 170.7W  145 KT 165 MPH

 36H  03/0600Z 17.7N 170.5W  140 KT 160 MPH

 48H  03/1800Z 20.7N 169.5W  125 KT 145 MPH

 72H  04/1800Z 27.1N 167.3W  100 KT 115 MPH

 96H  05/1800Z 31.0N 167.0W   75 KT  85 MPH

120H  06/1800Z 35.0N 163.0W   65 KT  75 MPH



$$

Forecaster Kodama