5AM Hurricane Updates in Detail

Expect rains here in Kohala for the next day or so from Erick but not really too much rain. However, Flossie is another matter. Nobody knows it’s path for sure. In fact, “It is worth noting that the confidence in the 5-day forecast position of Flossie is quite low, and the average error of track and intensity forecasts at that range is about 200 miles and 20 mph”. 

So, be prepared…….

HURRICANE ERICK:

500 AM HST Thu Aug 01 2019

Although Erick has the overall appearance of a hurricane facing an
increasing amount of headwind, deep convection near the center has
thus far prevented the environmental wind shear from disrupting the
inner core. Southwesterly shear near 20 kt is limiting outflow in
the southwest semicircle, but a burst of thunderstorms over the
center led to the development of a cloud-filled eye right around
analysis time. These strong thunderstorms and eye feature have
since persisted, but the southern portion of the eyewall looks
degraded in latest satellite images, and in an 1119Z ATMS pass.
Given those developments, and using a blend of the subjective and
automated Dvorak intensity estimates from PHFO/SAB/PGTW/UW-CIMSS,
the initial intensity for this advisory has been lowered slightly to
75 kt.

Tracking the cloud-filled eye leads to increased confidence in the
initial motion estimate of 285/13 kt. The track forecast continues
to expect a general motion just north of due west for most of the
forecast period, with a low- to mid-level ridge centered to the
north and northeast respectively providing the primary steering,
especially as Erick becomes increasingly shallow. A turn toward the
northwest, with some slowing in forward speed, is expected on days 4
and 5 as the ridge to the north weakens and lifts north. The updated
track forecast has changed little from the previous, and is close to
the ECMWF and HCCA guidance.

Erick is moving into an area of even stronger vertical wind shear,
associated with a semi-permanent upper-level trough northwest of the
main Hawaiian islands. Shear values along the forecast track
increase to 30-40 kt over the next 12 to 24 hours, and this
unrelenting shear is expected to lead to the demise of Erick as a
tropical cyclone. The bulk of the dynamical and statistical guidance
indicates that Erick will barely be hanging on as a tropical storm
in 48 hours, and the official forecast closely follows. Erick is
then expected to become a remnant low on days 4 and 5 before
dissipating shortly thereafter.

Erick is currently passing about 100 nm south of NOAA buoy 51004,
which is reporting seas over 14 feet, and is still about 375 nm
east-southeast of buoy 51002, where seas have reached 11 feet. This
data was used to increase the radii of 12 foot seas in the northwest
semicircle. A partial ASCAT pass around 0733Z led to a reduction to
the 34 kt radii in the northern semicircle. Six-hourly soundings
will begin at PHTO later today.

FORECAST POSITIONS AND MAX WINDS

INIT 01/1500Z 15.9N 152.4W 75 KT 85 MPH
12H 02/0000Z 16.1N 154.5W 60 KT 70 MPH
24H 02/1200Z 16.6N 157.2W 50 KT 60 MPH
36H 03/0000Z 17.2N 159.8W 45 KT 50 MPH
48H 03/1200Z 17.7N 162.2W 35 KT 40 MPH
72H 04/1200Z 19.4N 165.6W 30 KT 35 MPH
96H 05/1200Z 21.0N 168.0W 30 KT 35 MPH…POST-TROP/REMNT LOW
120H 06/1200Z 22.5N 170.0W 25 KT 30 MPH…POST-TROP/REMNT LOW

HURRICANE FLOSSIE:

500 AM HST Thu Aug 01 2019

The structure of Flossie hasn’t changed in any meaningful way since
last night. Recent SSMI microwave data indicate that the center of
the tropical storm is displaced to the northwest of all of its deep
convection, and its IR presentation hasn’t changed since the last
advisory. Since Flossie’s appearance and structure has been nearly
steady-state, the initial intensity remains 55 kt, based primarily
on earlier ASCAT data.

The NHC intensity forecast is very similar to the previous advisory,
and Flossie is still expected to remain a tropical storm for the
next 5 days. The intensity guidance is finally in good agreement on
the forecast, and all of the models indicate that that Flossie’s
strength will not change substantially for the next day or two,
followed by gradual weakening through early next week. In fact, the
GFS now forecasts that Flossie will dissipate in about 5 days. The
new official intensity forecast is near the middle of the intensity
guidance envelope and is very close to IVCN at all forecast hours.

The initial motion of the cyclone is still 285/14 kt. There is high
confidence in the first 72 h the track forecast, and all of the
guidance continues to keep Flossie near its current heading and
speed through that period. The spread increases dramatically after
that, with the regional models (HWRF, HMON, COAMPS-TC) all taking a
weak Flossie farther south, possibly even south of Hawaii, while the
global models all show Flossie recurving east of the islands ahead
of a mid- to upper-level trough. For the moment, the NHC forecast
continues to favor the global model solution and does not show a
significant change to the track forecast, however it has been
tweaked slightly southward at days 4 and 5.

It is worth noting that the confidence in the 5-day forecast
position of Flossie is quite low, and the average error of track and
intensity forecasts at that range is about 200 miles and 20 mph,
respectively. In addition, hazards associated with tropical storms
extend well away from the center of circulation. Users should
therefore consult local forecasts from the National Weather Service
Forecast Office in Honolulu, Hawaii, at www.weather.gov/hfo for
information specific to the Hawaiian Islands.

FORECAST POSITIONS AND MAX WINDS

INIT 01/1500Z 15.1N 131.6W 55 KT 65 MPH
12H 02/0000Z 15.6N 133.9W 55 KT 65 MPH
24H 02/1200Z 16.3N 136.9W 55 KT 65 MPH
36H 03/0000Z 16.9N 139.8W 55 KT 65 MPH
48H 03/1200Z 17.5N 142.5W 50 KT 60 MPH
72H 04/1200Z 18.4N 147.5W 45 KT 50 MPH
96H 05/1200Z 19.5N 152.5W 45 KT 50 MPH
120H 06/1200Z 22.5N 155.5W 35 KT 40 MPH