277 
 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
  
 

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