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Tropical Depression Greg Discussion Number 16
NWS Central Pacific Hurricane Center Honolulu HI EP082023
1100 AM HST Thu Aug 17 2023
Greg has been able to produce relatively short-lived bursts of
convection in its northern semicircle over the past 12 to
18 hours, but it has been occurring significantly far from the
increasingly ill-defined low-level circulation center. Shear is
analyzed to be relatively light, but satellite observations
indicate that even this morning's flare-up of thunderstorms
have been unable to wrap around the cyclone's core. Subjective
Dvorak intensity estimates are 1.5/2.5 from PHFO/PGTW, with SAB
determining that Greg is too weak to classify. Automated intensity
estimates from UW-CIMSS are all below tropical-storm-strength, and a
blend of these estimates yields an initial intensity estimate of
30 kt.
The initial motion vector for this advisory is 270/11 kt. Greg will
move generally toward the west (or just south of west) with the
trade wind flow in which it is embedded for the remainder of its
existence. The latest track forecast represents little change from
the previous, and lies close to TVCE and EMXI guidance. While SSTs
along the forecast track are sufficiently warm to sustain a tropical
cyclone, Greg is expected to gradually weaken over the next day
or two as increasing vertical wind shear prevents convection from
persisting over the center. Greg will likely soon become post-
tropical, then dissipate by Saturday, with the official intensity
forecast placing the greatest weight on the dynamical guidance.
FORECAST POSITIONS AND MAX WINDS
INIT 17/2100Z 12.2N 157.1W 30 KT 35 MPH
12H 18/0600Z 12.1N 158.8W 30 KT 35 MPH...POST-TROPICAL
24H 18/1800Z 11.8N 161.3W 25 KT 30 MPH...POST-TROPICAL
36H 19/0600Z 11.4N 164.0W 25 KT 30 MPH...POST-TROPICAL
48H 19/1800Z...DISSIPATED
$$
Forecaster Birchard
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