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Hurricane Miriam Discussion Number 20
NWS Central Pacific Hurricane Center Honolulu HI EP152018
500 PM HST Thu Aug 30 2018
Deep convection has been pulsing and producing bursts of lightning
near the center of Miriam today, but after a brief sighting this
morning, an eye has not reappeared in traditional satellite
imagery. Dvorak current intensity estimates from HFO/SAB/GTW remain
4.5/77 kt, and with little overall change in the satellite
presentation from earlier today, the initial intensity will remain
75 kt for this advisory.
The initial motion estimate is 350/07 kt. A motion toward the north
will continue over the next 36 to 48 h, as Miriam is carried by the
gradient between a deep-layer ridge to the east and a deep-layer
trough to the north. Decreasing SSTs and increasingly strong
southwesterly vertical wind shear lie along the forecast path, and
Miriam's time as a tropical cyclone is limited. Gradual weakening
in the short term is expected to be followed by a more rapid rate
of decay between 24 h and 72 h, and Miriam is expected to become a
post-tropical remnant low on day 3, dissipating by day 5. As Miriam
weakens, it is expected to turn toward the northwest as it becomes
shallow and steered by the low-level trade flow. Track model
guidance is in better agreement as compared to 24 h ago, with the
GFS shifting markedly poleward over the past several runs, closer
to the other reliable dynamical aids. The CPHC track forecast was
shifted to the right of the previous and very closely mimics TVCE
and HCCA. The intensity forecast follows trends presented by all
reliable guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 31/0300Z 16.5N 141.6W 75 KT 85 MPH
12H 31/1200Z 17.9N 141.4W 70 KT 80 MPH
24H 01/0000Z 19.7N 141.5W 65 KT 75 MPH
36H 01/1200Z 21.5N 141.9W 50 KT 60 MPH
48H 02/0000Z 23.2N 143.0W 40 KT 45 MPH
72H 03/0000Z 26.6N 146.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 04/0000Z 30.0N 150.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 05/0000Z...DISSIPATED
$$
Forecaster Birchard
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