338 
 WTPA42 PHFO 242110
 TCDCP2
  
 Hurricane Lane Discussion Number  41
 NWS Central Pacific Hurricane Center Honolulu HI   EP142018
 1100 AM HST Fri Aug 24 2018
  
 Lane continues to struggle against 30 to 40 kt of southwesterly 
 shear as analyzed by the UW-CIMSS shear analysis. The CDO continues 
 to be very asymmetric and elliptical. Radar, lightning data, and 
 1645z Windsat pass indicated that the active convection has been 
 shunted to the northwest through north of the low level circulation 
 center, indicating that the core of the tropical cyclone is getting
 torn apart by the shear. Subjective current intensity estimates were
 unanimous at 5.0, and CIMSS-ADT had 5.1. The initial intensity was
 lowered to 90 kt for this advisory.
 
 The initial motion estimate a rather uncertain 360/4. The changes to
 Lane's structure make the near term track forecast very difficult,
 as the steering layer will be rapidly evolving in the short term.
 The proximity to island terrain makes the steering flow even more
 complex, at least until the vortex completely seperates from the
 persistent convection as a shallow low level circulation. Until
 then, the motion is likely to be somewhat slow and erratic. The
 reliable track guidance suggests a slow north or north-northeastward
 drift for the next 12 hours, followed by an abrupt shift toward the
 west at some point afterward. The consensus models show a general
 westward motion from 24 through 96 hours, then turning more toward
 the northwest. The only significant change to the track forecast
 during this time was to slow Lane's forward motion. If anything is
 left of Lane between 96 and 120 hours, the low level circulation
 may gain latitude and try to merge with a large upper low over the
 Northwestern Hawaiian Islands.
 
 As long as Lane can maintain central deep convection, the weakening
 trend will remain more gradual. More rapid weakening will commence
 within 12 to 24 hours, once the convection is no longer able to
 remain anchored to the low level circulation center. All of the
 guidance indicates rather rapid weakening in the near term, and our
 forecast agrees though is at the high end of the guidance in
 deference to Lane's persistent core. Although the current forecast
 retains Lane as a tropical cyclone through 5 days, it's very
 possible that Lane will not last that long as the low level
 circulation crosses underneath a band of very strong wind shear.
 
  
 KEY MESSAGES:
  
 1. One should not interpret the forecast westward turn south of the 
 islands as a lower threat to the islands. If Lane retains central 
 core convection longer than anticipated, the westward turn would 
 happen later, which could bring hurricane conditions to Maui County 
 or Oahu. This solution is still plausible at this time. Regardless 
 of whether Lane makes landfall, severe impacts are still possible 
 and the effects can extend far to the north and east of the center 
 of Lane.
  
 2. Lane will remain dangerously close to the central Hawaiian
 Islands as a hurricane today into tonight bringing damaging winds
 to some areas. Terrain effects can cause strong localized
 acceleration of the wind through gaps and where winds blow
 downslope. These acceleration areas will shift with time as Lane
 passes near or over the islands. Winds will also be stronger at the
 upper floors of high rise buildings.
  
 3. The slow movement of Lane greatly increases the threat for
 prolonged heavy rainfall. This is expected to lead to major flash
 flooding and landslides in some areas.
  
 4. Life-threatening and damaging surf can be expected along exposed
 shorelines with localized storm surge exacerbating the impacts of a
 prolonged period of damaging surf. The prolonged period of large
 surf will also likely produce severe beach erosion.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  24/2100Z 19.1N 157.9W   90 KT 105 MPH
  12H  25/0600Z 19.7N 157.7W   75 KT  85 MPH
  24H  25/1800Z 20.2N 158.1W   65 KT  75 MPH
  36H  26/0600Z 20.2N 159.4W   55 KT  65 MPH
  48H  26/1800Z 20.1N 160.8W   45 KT  50 MPH
  72H  27/1800Z 20.4N 163.4W   35 KT  40 MPH
  96H  28/1800Z 22.4N 165.7W   30 KT  35 MPH
 120H  29/1800Z 26.7N 168.5W   30 KT  35 MPH
  
 $$
 Forecaster R Ballard