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Tropical Depression ALETTA


Tropical Depression Aletta Discussion Number  24
NWS National Hurricane Center Miami FL       EP022018
800 AM PDT Mon Jun 11 2018

Aletta has been devoid of any significant convection for about 8
hours due to the cyclone ingesting dry mid- and upper-level air
along with an abundance of stable, low-level cold-air stratocumulus
clouds. The combination of these unfavorable thermodynamic
conditions and SSTs less than 26C beneath the cyclone should result
in Aletta degenerating into a remnant low pressure system later
today, possibly as early as the next advisory cycle. The initial
intensity of 30 kt is based on an average of Dvorak T- and CI-
numbers from TAFB, and an assumed spin down from the 35-kt winds
noted in 0532 UTC ASCAT data.

Microwave satellite fixes indicate that Aletta has been moving
westward at about 10 kt since the previous advisory. However, this
is likely just a temporary motion due to the decoupling of the
low- and upper-level circulations owing to the loss of convection.
As a result, the advisory motion is estimated to be a slower 270/06
kt. Aletta is expected to move westward today, followed by a turn
toward the west-southwest by Tuesday due to the shallow cyclone
being steered by the low-level easterly to northeasterly tradewind
flow. By days 3 and 4, the steering flow is forecast to weaken
significantly, causing Aletta to possibly stall, due to the remnant
low coming under the influence of major Hurricane Bud's expanding
circulation. The NHC track guidance is in good agreement on this
developing track scenario, and the new forecast track is similar to
the previous advisory and the consensus models HCCA and TVCN.


INIT  11/1500Z 16.8N 117.8W   30 KT  35 MPH
 12H  12/0000Z 16.7N 118.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 24H  12/1200Z 16.5N 119.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  13/0000Z 16.3N 120.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  13/1200Z 16.1N 120.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  14/1200Z 16.0N 120.2W   15 KT  15 MPH...POST-TROP/REMNT LOW
 96H  15/1200Z 16.0N 120.0W   15 KT  15 MPH...POST-TROP/REMNT LOW
120H  16/1200Z...DISSIPATED

Forecaster Stewart