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Tropical Depression Twelve-E Discussion Number 2
NWS National Hurricane Center Miami FL EP122023
Issued by NWS Central Pacific Hurricane Center Honolulu HI
500 PM HST Fri Sep 15 2023
Tropical Depression 12E has a fully exposed low level center. Deep
convection is displaced about 60 nm to the east, in the face of 15
to 20 kt of westerly shear as analyzed by the UW-CIMSS shear
analysis. A blend of the satellite-based intensity estimates
suggests maintaining a 25 kt intensity for this advisory.
The low level center has been moving rather erratically today as it
decouples from the deep convection. A longer term initial motion
estimate is 255/8, but it should be noted this is less certain than
normal due to the wobbles seen today. 12E is expected to continue
moving toward the west-southwest in the low level trade wind flow
well south of a subtropical ridge. The official forecast has been
nudged a bit to the south, in deference to the recent trends in low
level motion after decoupling. Our forecast track is fairly close
to the middle of the guidance envelope for the expected duration of
the system.
Guidance suggests that over the next few days, the subtropical jet
will sag south over the central Pacific, with a gradual increase in
shear over the system. The low level center will be moving over
slightly warmer sea surface temperatures over the next couple of
days, which suggests that an intermittent bursts of deep convection
will be possible, but significant reintensification seems unlikely.
Simulated satellite imagery from the GFS and ECMWF also agree
with this idea. The depression is forecast to become a remnant low
in about 36 hours, leading to dissipation in a couple of days far
southeast of Hawaii.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0300Z 14.6N 136.8W 25 KT 30 MPH
12H 16/1200Z 14.4N 137.8W 25 KT 30 MPH
24H 17/0000Z 14.1N 139.3W 25 KT 30 MPH
36H 17/1200Z 13.9N 141.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 18/0000Z 13.7N 142.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 18/1200Z...DISSIPATED
$$
Forecaster R Ballard
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