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Tropical Storm Marty Discussion Number   5
NWS National Hurricane Center Miami FL       EP132021
200 AM PDT Tue Aug 24 2021

Satellite imagery indicates that Marty is currently a swirl of 
low-level clouds with no associated convection, with this likely due 
to a combination of northeasterly vertical shear and marginal sea 
surface temperatures.  Recent ASCAT data shows maximum winds of 
30-35 kt over a small area in the northern semicircle, so the 
initial intensity is reduced to 35 kt.  

The initial motion is still westward, but slower than before, at 
270/11 kt.  The subtropical ridge to the north of Marty will 
continue to steer the cyclone generally westward over the next day 
or two.  After that, the weakening cyclone is expected to turn west- 
southwestward during the latter part of the week within the 
low-level trade wind flow.  The new forecast track is similar to, 
but a little slower than the previous forecast, and it lies near the 
various consensus models.

Although the current shear is forecast to diminish, a combination of 
decreasing sea surface temperatures and a dryer air mass along the 
forecast track should cause continued gradual weakening.  The new 
intensity forecast shows the system weakening to a depression in 
about 24 h and degenerating to a remnant low by 48 h.  If convection 
does not re-develop near the center, both of these events could 
occur earlier than forecast.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/0900Z 20.6N 117.0W   35 KT  40 MPH
 12H  24/1800Z 20.6N 118.7W   35 KT  40 MPH
 24H  25/0600Z 20.6N 120.9W   30 KT  35 MPH
 36H  25/1800Z 20.7N 122.8W   25 KT  30 MPH
 48H  26/0600Z 20.6N 124.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 60H  26/1800Z 20.4N 127.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  27/0600Z 19.8N 129.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  28/0600Z 18.5N 134.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  29/0600Z...DISSIPATED
 
$$
Forecaster Beven
 
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