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Hurricane Dora Discussion Number 38
NWS Central Pacific Hurricane Center Honolulu HI EP052023
1100 AM HST Wed Aug 09 2023
Dora continues to track westward across the central North Pacific,
unscathed by shear and sustained by marginally warm ocean water.
Satellite presentation includes a clearly-defined eye and a
symmetrical central structure. While the periphery is a bit ragged
in appearance, there is little or no evidence of shear effects.
Surrounding dry air has not been entrained sufficiently to erode
the core. Dora is very slowly gaining latitude but will pass far
south of Johnston Island later today. All three fix agencies have
derived subjective Dvorak intensity estimates of 6.0, corresponding
to 115 kt. Latest UW-CIMSS ADT intensity is also 115 kt. Given the
overall unchanged appearance of Dora over the past six hours, the
obvious move is to assign her an initial intensity of 115 kt.
Initial motion with this advisory is 275/19 kt, unchanged from the
last advisory. Track guidance remains remarkably tight through tau
72, with spread only becoming significant at tau 96 and tau 120,
long after this system has passed out of the basin into the western
North Pacific. Strong ridging north of Dora, and the westward
migration of this ridging, accounts for this system's prolonged
westward movement. However, the slow and rather recent increase in
latitude indicates that Dora is reaching the southwest periphery of
this ridging and is poised to begin a track to the west northwest.
This track swing will continue as Dora is forecast to assume a
northwest motion Thursday and Friday. The forecast track, closely
following the previous track and TVCN model consensus, continues to
become more northerly after Dora passes west of the date line.
Warm water, with temperatures of 28 degrees C or above, lies along
the entire forecast track and shear will be minimal through tau 72.
With 18Z ECMWF SHIPS showing almost no Dora intensity drop through
tau 36, this advisory will only slowly weaken this system through
tau 60, with more pronounced weakening introduced afterwards as
Dora gains latitude and shear increases. The 18Z GFS SHIPS shows a
similar slow weakening trend, but through tau 24. Both SHIPS
versions keep Dora stronger at all tau than most intensity model
guidance, but Dora's demonstrated resilience increases confidence
that a slower weakening trend, at least initially, is reasonable.
Dora will eventually weaken to a post-tropical/remnant low, but
just after tau 120.
FORECAST POSITIONS AND MAX WINDS
INIT 09/2100Z 11.6N 166.0W 115 KT 130 MPH
12H 10/0600Z 12.0N 168.9W 115 KT 130 MPH
24H 10/1800Z 12.8N 172.5W 110 KT 125 MPH
36H 11/0600Z 13.7N 175.7W 110 KT 125 MPH
48H 11/1800Z 14.8N 178.7W 105 KT 120 MPH
60H 12/0600Z 15.7N 178.5E 100 KT 115 MPH
72H 12/1800Z 16.5N 175.9E 90 KT 105 MPH
96H 13/1800Z 17.7N 171.1E 65 KT 75 MPH
120H 14/1800Z 19.1N 167.1E 50 KT 60 MPH
$$
Forecaster Powell
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