041 
 WTPA41 PHFO 030332
 TCDCP1
  
 Hurricane Walaka Discussion Number  14...Corrected
 NWS Central Pacific Hurricane Center Honolulu HI   CP012018
 500 PM HST Tue Oct 02 2018
  
 Walaka's eye has become less distinct in conventional satellite 
 imagery over the last couple of hours, with subjective intensity 
 estimates and CIMSS-ADT unanimous at 6.0. Thus, the current 
 intensity has been lowered to 115 kt for this advisory. Despite 
 these recent trends, a 0151 UTC SSMI pass continued to show a well-
 developed eyewall, and there are well-developed outflow channels to 
 the northeast and southeast of the hurricane. Outflow is much more 
 restricted in the western semicircle. 
 
 The initial motion estimate is 010/11, as Walaka moves generally 
 toward a vertically-stacked low pressure area near 31N 170W. Walaka 
 is expected to soon begin accelerating toward the north-northeast
 as it gets caught up in the warm conveyor belt on the east side of
 the low. As Walaka begins to get tangled up with this extratropical 
 feature, the guidance shows the center will dramatically slow it's 
 forward motion in the 48 to 72 hour time frame and may take a brief 
 bend back toward the north-northwest, then kick northeast rapidly 
 again at 96 hours and beyond as the circulation becomes more 
 shallow. The track guidance remains in remarkably good agreement 
 considering the rather complex interaction between Walaka and the 
 extratropical low, and this forecast track is similar to the 
 previous advisory package.
 
 The UW-CIMSS shear analysis shows that Walaka will be coming under 
 the influence of moderate to strong shear relatively soon. The shear
 is expected to peak at greater than 30 kt by 36 hours, which should
 continue the weakening trend. Although the shear diminishes beyond
 36 hours, the cyclone will begin moving over increasingly cool sea
 surface temperatures. There is some uncertainty as to how Walaka's
 interaction with the extratropical low will play out. The global
 models seem to be in good agreement that some semblance of a warm
 core will remain even afterward, and so the forecast maintains
 Walaka as a tropical cyclone through 96 hours. It would not be
 surprising if the system becomes extratropical sooner, however. The
 forecast shows a slower rate of weakening than most of the dynamical
 models, in best agreement with the ECMWF through 48 hours, then
 aligns with SHIPS guidance afterward.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  03/0300Z 16.7N 170.2W  115 KT 130 MPH
  12H  03/1200Z 18.7N 169.7W  110 KT 125 MPH
  24H  04/0000Z 21.9N 168.5W  105 KT 120 MPH
  36H  04/1200Z 25.5N 167.4W   95 KT 110 MPH
  48H  05/0000Z 28.9N 167.6W   85 KT 100 MPH
  72H  06/0000Z 32.0N 166.4W   65 KT  75 MPH
  96H  07/0000Z 38.7N 160.6W   50 KT  60 MPH
 120H  08/0000Z 46.8N 152.1W   40 KT  45 MPH...POST-TROP/EXTRATROP
  
 $$
 Forecaster R Ballard
  
 

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