Hurricane Lane Discussion Number 24
NWS Central Pacific Hurricane Center Honolulu HI EP142018
1100 AM HST Mon Aug 20 2018
Air Force Reserve Hurricane Hunters found a maximum flight level
wind of 121 kt, and the NOAA Hurricane Hunters found maximum SFMR
wind of 113 kt earlier on the northwest quadrant. The 15 to 20 nm
diameter eye had also temporarily become more distinct over the past
6 to 8 hours, and this was the justifiation for raising the current
intensity slightly to 115 kt. This is somewhat higher than the 18z
satellite based estimates were showing. The eye has since started
to become less distinct once again in satellite imagery.
The initial motion is 280/10, slightly slower than the previous
advisory. Lane is marching toward the west on the southern flank
of a large subtropical ridge. In the near term, the track guidance
is in excellent agreement. This motion is expected to gradually turn
more toward the west-northwest, and then finally northwest over the
next few days as the ridge weakens and erodes. Beyond 48 hours, the
forecast becomes quite challenging. The guidance shows increasing
spread due to noteworthy differences in the handling of the strength
of the ridge to the east and southeast of the cyclone. The GFS
remains on the far right side of the guidance with a harder right
turn starting around 72 hours, and the ECMWF shows a more gentle
curve. The consensus guidance remains split down the middle of these
two camps and did not change much from the previous advisory. The
forecast track at 96 hours was nudged slightly eastward to better
agree with the consensus guidance, but it should be noted that in
this situation, forecast confidence is lower than normal. A turn
back toward the west-northwest is expected toward the end of the
forecast period as strong wind shear begins to impact Lane, but this
is also a rather low confidence scenario.
Lane is expected to remain over 28C sea surface temperatures in the
short term in a weak to moderate shear environment that should allow
the hurricane to maintain intensity. After a day or two, the models
show increasing shear beginning to work on the circulation and
weaken the system. However, there are some differences as to when
that will begin. The intensity forecast shows a slow weakening
trend beginning in the 24 to 36 hour time frame in good agreement
with the intensity consensus guidance. Once shear increases in the
48 to 72 hour time frame, a somewhat faster weakening trend is
anticipated which should continue through the rest of the forecast
period.
Interests in the main Hawaiian Islands, as well as the northwestern
Hawaiian Islands, should continue to monitor the progress of Lane
this week. With such a complex forecast scenario, it is especially
important not to focus on the exact forecast track and intensity
and be ready for changes to both.
FORECAST POSITIONS AND MAX WINDS
INIT 20/2100Z 13.6N 149.1W 115 KT 130 MPH
12H 21/0600Z 13.7N 150.6W 115 KT 130 MPH
24H 21/1800Z 13.9N 152.3W 115 KT 130 MPH
36H 22/0600Z 14.3N 153.9W 110 KT 125 MPH
48H 22/1800Z 14.9N 155.3W 105 KT 120 MPH
72H 23/1800Z 16.9N 157.2W 95 KT 110 MPH
96H 24/1800Z 19.4N 158.8W 75 KT 85 MPH
120H 25/1800Z 20.6N 160.4W 55 KT 65 MPH
$$
Forecaster R Ballard
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