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Hurricane Erick Discussion Number  21
NWS Central Pacific Hurricane Center Honolulu HI   EP062019
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
 
$$
Forecaster Birchard
 
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