ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
 
Tropical Depression Seventeen-E Discussion Number   3
NWS National Hurricane Center Miami FL       EP172020
300 AM MDT Mon Sep 21 2020
 
The depression has really gone downhill overnight. While a small
well-defined center probably still exists, a pair of ASCAT passes
between 4 and 5 UTC showed that the surface circulation of the 
depression is generally elongated, with a large area of light and 
variable winds where you would expect north and northwest winds. 
Deep convection is displaced well to the west of the estimated 
center position due to persistent easterly shear. The highest winds 
in either ASCAT pass were just below 25 kt, so that remains the 
intensity for this advisory.
 
The depression has apparently accelerated west-northwestward, with
an extremely uncertain motion estimate of 285/11 kt. A turn toward
the west is anticipated by Wednesday and extensive ridging to the
north will likely keep the cyclone heading generally westward 
thereafter through the end of the forecast period. This track will 
take the cyclone parallel to an SST gradient that will have 
implications on the intensity forecast.
 
The poor organization of the depression suggests that any 
strengthening will be slow to occur during the next day or two. 
Moderate easterly shear will likely continue for at least another 
couple days, but the cyclone could find itself in a quite favorable 
upper-air environment in a few days. If it is located on the warm 
side of the SST gradient, some strengthening is likely, though 
surrounding dry air will likely be a limiting factor for rapid any 
intensification. One model with a southern track, the HWRF, even 
suggests it could become a hurricane later this week. If the system 
moves a little farther north that currently forecast, little 
strengthening will be likely and it could even become a remnant low 
at some point during the next 5 days. The NHC intensity forecast is 
similar to the previous one, but shows a slightly slower rate of 
strengthening for the first three days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 16.6N 110.8W   25 KT  30 MPH
 12H  21/1800Z 17.4N 112.5W   30 KT  35 MPH
 24H  22/0600Z 18.5N 114.8W   35 KT  40 MPH
 36H  22/1800Z 19.3N 116.9W   40 KT  45 MPH
 48H  23/0600Z 19.9N 118.9W   50 KT  60 MPH
 60H  23/1800Z 20.2N 120.6W   55 KT  65 MPH
 72H  24/0600Z 20.4N 122.4W   60 KT  70 MPH
 96H  25/0600Z 20.5N 125.5W   60 KT  70 MPH
120H  26/0600Z 20.5N 129.0W   55 KT  65 MPH
 
$$
Forecaster Zelinsky
 
NNNN