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Hurricane Miriam Discussion Number 19
NWS Central Pacific Hurricane Center Honolulu HI EP152018
1100 AM HST Thu Aug 30 2018
Miriam's satellite appearance improved early this morning, when a
banding type eye appeared in traditional satellite imagery shortly
after a well-developed eye was evident in a 1326Z GPM microwave
overpass. Cold cloud tops briefly encircled a portion of the eye,
but the eye is now cloud-filled once again. Subjective Dvorak
intensity estimates from HFO/SAB/GTW trended up to 4.5/77 kt, and
the initial intensity estimate for this advisory has been increased
to 75 kt. The initial motion estimate is 330/7 kt.
The window for additional strengthening is expected to soon close
as Miriam moves north into an area of very strong vertical wind
shear and decreasing SSTs. Miriam will move nearly due north in the
deep southerly flow between a ridge to the east and a trough to the
north. This gradient will also increase vertical wind shear to near
30 kt in 24-36 h. SSTs currently near 28C will drop below 26C after
48 h, with the cumulative effects leading to a fairly fast rate of
weakening after tomorrow. The shallow remnant of Miriam is then
expected to make a turn toward the northwest, primarily steered by
the low-level trade wind flow, and is expected to be close to
dissipation by the end of the forecast period. The official track
forecast is on the left hand side of the guidance envelope, but has
been nudged to the right at almost all time frames, to be more in
line with the TVCE and HCCA ensembles. The intensity forecast
follows trends presented by all reliable guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 30/2100Z 15.7N 141.6W 75 KT 85 MPH
12H 31/0600Z 17.0N 141.7W 80 KT 90 MPH
24H 31/1800Z 18.7N 141.5W 75 KT 85 MPH
36H 01/0600Z 20.4N 141.6W 60 KT 70 MPH
48H 01/1800Z 22.1N 142.5W 45 KT 50 MPH
72H 02/1800Z 25.0N 145.0W 35 KT 40 MPH
96H 03/1800Z 28.0N 149.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 04/1800Z 30.0N 154.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
Forecaster Birchard
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