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Tropical Depression Ignacio Discussion Number   7
NWS National Hurricane Center Miami FL       EP102021
200 AM PDT Tue Aug 03 2021
 
Strong east-northeasterly shear has continued to take a toll on
Ignacio overnight with a small cluster of remaining deep convection
now displaced over 60 n mi to the southwest of the center. An ASCAT
overpass that arrived shortly after the release of the previous
advisory indicates that Ignacio has weakened to a tropical
depression with peak winds of around 30 kt. That is also supported
by a blend of the latest Dvorak T- and CI-numbers from TAFB and SAB.
The strong shear and marginal SSTs should continue to cause gradual
weakening over the next 12-24 hours, and Ignacio is expected to
become a remnant low Tuesday night. The GFS, ECMWF, and UKMET all
show the remnant low opening up into a trough of low pressure
shortly thereafter, and so does the official forecast.
 
Ignacio is moving slower toward the northwest than before, or about
315/5 kt.  A further reduction in forward speed is predicted over
the next 12-24 hours as Ignacio weakens and is steered by the weaker
low-level flow.  The track guidance again suggests that the remnant
low will turn northeastward before dissipating, and the updated NHC
track forecast has been adjusted accordingly.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  03/0900Z 20.1N 116.3W   30 KT  35 MPH
 12H  03/1800Z 20.9N 116.9W   25 KT  30 MPH
 24H  04/0600Z 21.2N 116.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
 36H  04/1800Z...DISSIPATED
 
$$
Forecaster Brown
 
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