Alert:
…THE NATIONAL WEATHER SERVICE HAS ISSUED A FLOOD POTENTIAL
OUTLOOK FOR THE STATE OF HAWAII…
…HURRICANE LANE WILL BRING THE POTENTIAL FOR HEAVY RAINS AND
FLASH FLOODING THIS WEEK…
The latest forecast from the Central Pacific Hurricane Center
indicates that the center of Hurricane Lane will pass south and
southwest of the islands this week. As the impacts from a hurricane
extend well away from the center, associated heavy rains are
expected to impact the islands.
Latest forecast models indicate that, regardless of the eventual
track and intensity of Lane, an extremely moist and unstable air
mass will move over the islands beginning around Wednesday, and
will remain in place through the end of the week. This is
expected to result in very heavy rainfall, potentially leading to
flash flooding.
The details on the timing and location of the heavy rain are
still uncertain. Please keep yourself informed through NOAA
Weather Radio or local media for forecast updates.
500 AM HST Mon Aug 20 2018
Aircraft from the NOAA Aircraft Operation Center and the U.S. Air
Force Reserves 53rd Weather Reconnaissance Squadron departed
Hurricane Lane late Sunday evening. In the meantime, we are relying
on satellite imagery to track Lane’s progress. A warm spot, which
appears to be indicative of an eye, appeared in the infrared
satellite imagery several hours ago. Radar reflectivity data sent
from the NOAA aircraft between 0510z and 0722z showed that Lane’s
eyewall was open in the southeastern quadrant. More recently, a
1237z SSMI microwave image appears to show that the eyewall has now
become distinct in all quadrants. All of the satellite fix agencies
(PHFO, SAB, and JTWC) based their subjective Dvorak current
intensity estimates on an “eye pattern”. These estimates ranged
from 90 to 102 knots. The latest UW-CIMSS ADT estimate appears to be
an unrealistically low 77 knots. Since the aircraft observations
were much stronger earlier tonight and the overall appearance of
the hurricane appears to be improving, we will maintain the initial
intensity at 110 knots.
The initial motion for this advisory is 275/12 knots. Lane continues
to track westward along the southern flank of a large subtropical
ridge. There is still significant spread in the track guidance
beyond day 2 due to the variations in the way the individual models
handle the erosion of the western portion of this ridge as an
upper-level trough digs down northwest of the main Hawaiian Islands
in about 72 hours. The latest forecast track through 48 hours is
close to the previous forecast. However, due to overwhelming
evidence that the western end of the ridge will erode from days 3
through 5, we again had to shift the track far to the right. The
latest forecast track is much closer to the TVCN/TVCX and GFEX
consensus models. It is also to the right of the ECMWF, and to
the left of the GFS and HWRF track guidance. Note that another NOAA
G-IV mission to sample the environment around Lane is scheduled for
this afternoon. The data from this aircraft will be used to improve
the initial fields in the hurricane forecast models.
The latest inensity forecast has been nudged up slightly compared
with the previous one. Lane will remain over 27-28 degree C waters
through the forecast period. Shear of 10 to 15 knots is expected
during the next 6 hours or so, followed by reduced shear during the
12 to 48 hour time periods. After that, vertical shear is expected
to increase, which would likely result in steady weakening. Lane
may possibly become a tropical storm by day 5. This intensity
forecast closely follows the IVCN consensus guidance. Note that
with the eye becoming more distinct, there is a possibility that
Lane may be undergoing a new period of intensification. Additional
reconnaissance aircraft will be flying into the system soon, so we
expect to receive direct measurements of the cyclone’s intensity in
a few hours.
Due to the large uncertainty in the future track and intensity of
Lane, all interests in the Hawaiian Islands, including the
Northwestern Hawaiian Islands, should continue to closely monitor
the future progress of this system. Based on the latest trends in
the forecast, direct impacts on the islands appear to be
increasingly likely. The latest trends in tropical cyclone wind
speed probabilities also suggest that a Tropical Storm or Hurricane
Watch may be needed for some parts of the island chain later today
or tonight.