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Tropical Depression Marty Discussion Number 6
NWS National Hurricane Center Miami FL EP132021
800 AM PDT Tue Aug 24 2021
There has been no significant deep convection within 100 nmi of
Marty's center since about 0600 UTC. The cyclone's cloud pattern now
consists of some mid-level clouds and mostly low-level cold-air
stratocumulus clouds. The current intensity of 30 kt is based on a
unanimous Dvorak satellite classification of T1.5/2.5 (25 kt/35 kt)
from TAFB and SAB, which has resulted in Marty being downgraded to
a tropical depression. Due to the cyclone's future track remaining
over sub-26C sea-surface temperatures, coupled with additional
entrainment of stable low clouds, Marty is now forecast to
degenerate to a post-tropical remnant low later today. The new
NHC intensity forecast closely follows the trends of the intensity
consensus models IVCN and NOAA-HCCA.
The initial motion remains westward, or 270/10 kt. The strong
deep-layer ridge to the north of the weakening shallow cyclone is
expected to keep Marty on a generally westward track over the next
36 hours or so, followed by a west-southwestward motion thereafter
until the cyclone dissipates. The new official forecast track lies
near the extreme southern edge of the model guidance envelope, owing
to the models' slight poleward bias noted over the past 36 hours.
FORECAST POSITIONS AND MAX WINDS
INIT 24/1500Z 20.6N 118.1W 30 KT 35 MPH
12H 25/0000Z 20.6N 119.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 25/1200Z 20.6N 121.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 26/0000Z 20.6N 124.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
48H 26/1200Z 20.5N 126.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
60H 27/0000Z 20.2N 128.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 27/1200Z 19.6N 130.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 28/1200Z...POST-TROP/REMNT LOW
$$
Forecaster Stewart
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