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Hurricane Marie Discussion Number 18
NWS National Hurricane Center Miami FL EP182020
800 AM PDT Sat Oct 03 2020
Marie shows little signs of weakening this morning as its satellite
presentation remains impressive. A closed ring of eyewall
convection with cloud top temperatures colder than -65 degrees C
surrounds a well-defined 20 nm eye. The initial intensity is
maintained at 115 kt based on a T6.0 Dvorak classification from
SAB, which is supported by the latest ADT estimates.
Marie is approaching an environment of increasing deep-layer
southwesterly shear and SSTs below 26 degrees Celsius, which should
induce weakening beginning later today that will continue through
early next week. The latest SHIPS guidance indicates the vertical
wind shear will strengthen to 30 kt by Mon and continue increasing
through the end of the 5-day forecast period. Therefore, Marie is
forecast to weaken to a tropical storm by early Monday and a
tropical depression by the middle of next week. The NHC intensity
forecast is held a bit higher than the model consensus through the
first 12-24 hours of the forecast, since Marie has yet to show
signs of weakening. As the environmental conditions become
increasingly hostile, the official forecast shows more rapid
weakening in line with the consensus intensity guidance. By day 5,
simulated satellite imagery suggests the system will be a remnant
low devoid of deep convection.
Marie's initial motion is 310/8 kt, and the system is expected to
generally continue moving northwestward for the next several days
along the southwest periphery of a mid-level ridge. A deep-layer
trough is expected to dig north of Marie during the middle of
next week, which should begin turning the system more northward
toward the end of the 5-day forecast period. A larger spread in the
guidance is noted at days 4-5, as it remains somewhat unclear how
much the trough will influence the weakening system based on timing
differences between the GFS and ECMWF models. Overall, the NHC
track forecast remains fairly close to the previous one, with
slight changes based on the consensus aids including TVCE and HCCA.
FORECAST POSITIONS AND MAX WINDS
INIT 03/1500Z 18.4N 126.9W 115 KT 130 MPH
12H 04/0000Z 19.1N 127.7W 105 KT 120 MPH
24H 04/1200Z 20.0N 128.7W 90 KT 105 MPH
36H 05/0000Z 20.6N 129.8W 70 KT 80 MPH
48H 05/1200Z 21.2N 131.2W 55 KT 65 MPH
60H 06/0000Z 21.9N 132.4W 45 KT 50 MPH
72H 06/1200Z 22.5N 133.7W 40 KT 45 MPH
96H 07/1200Z 23.5N 135.5W 30 KT 35 MPH
120H 08/1200Z 24.5N 136.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
$$
Forecaster Reinhart/Berg
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