WTPZ45 KNHC 250839
Tropical Storm Daniel Discussion Number 6
NWS National Hurricane Center Miami FL EP052018
200 AM PDT Mon Jun 25 2018
Cloud tops have been steadily warming since the previous advisory
and the overall amount of convection has also been shrinking.
However, a small mass of convection has persisted near and over the
low-level center, and a 0443Z ASCAT partial pass indicated that the
wind field in the western semicircle hadn't changed since the
previous overpasses just 12 h prior. Therefore, it is assumed that
winds near 40 kt still exists in the unsampled eastern semicircle.
The last UW-CIMSS SATCON estimate at 0225Z was 43 kt. Based on the
apparent lack of any significant low-level structural change noted
in the latest ASCAT data, along with the SATCON estimate, the
intensity is being maintained at 40 kt for this advisory.
The initial motion estimate is 330/09 kt. Daniel is expected to
gradually make a turn toward the northwest within the next 12 h as
the small cyclone moves around the eastern periphery of a mid- to
upper-level low located about 450 nmi to the west-southwest. As
Daniel moves over progressively cooler waters, the weakening cyclone
will become vertically more shallow and be steered westward by the
low-level easterly tradewind flow on days 2-4. The latest model
guidance remains good agreement with this developing track scenario.
As a result, the new NHC track forecast is similar to the previous
advisory track and is close to the consensus models TVCN and HCCA.
The small cyclone is currently located over sea-surface temperatures
(SST) of about 25C, with colder water lying ahead of the system.
Although the vertical wind shear is forecast to be low, steady
weakening and gradual erosion of the central convection is expected
throughout the forecast period due to the colder SSTs and a lack of
instability, especially after 12-18 hours. Daniel is forecast to
weaken to a depression by 24 h, and degenerate into a remnant low
pressure system shortly thereafter. However, given the current small
and relatively weak circulation, faster weakening could occur than
what is currently indicated. The latter scenario is supported by
the ECMWF and UKMET models, which show dissipation by 72 hours.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0900Z 18.8N 116.9W 40 KT 45 MPH
12H 25/1800Z 19.5N 117.8W 35 KT 40 MPH
24H 26/0600Z 20.2N 119.3W 30 KT 35 MPH
36H 26/1800Z 20.4N 121.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 27/0600Z 20.5N 122.8W 25 KT 30 MPH...POST-TROP/EXTRATROP
72H 28/0600Z 20.3N 126.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
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