168
WTPZ42 KNHC 202058
TCDEP2

Tropical Depression Seventeen-E Discussion Number   1
NWS National Hurricane Center Miami FL       EP172026
300 PM CST Sun Sep 20 2026

The tropical disturbance to the south of Mexico, formerly Invest
99E, has become better organized with some convective banding
features over its eastern semicircle.  Although a recent
scatterometer pass missed the circulation, low cloud motions
indicate that the system now has enough of a low-level circulation
to qualify as a tropical depression with an initial intensity of 30
kt this advisory.

The center has been difficult to track so far so the initial motion
is a rather uncertain 030/7 kt.  According to the majority of the
track guidance, the system is likely to turn eastward within the
next 12 to 24 hours.  This motion is apparently due to the system
being embedded within a broader cyclonic gyre near the southern
coast of Mexico.  Later in the forecast period, the system is
expected to turn toward the northwest and move on the southern side
of a mid-level high.  The official forecast is near the northern
side of the track guidance model envelope.

The depression should be situated within an environment that is
conducive for strengthening during the next few days, with very
light vertical wind shear, and very warm sea surface temperatures.
The official intensity forecast is near the model consensus and
shows the system becoming a hurricane in 36 h.  It should be noted
that the Google DeepMind and HCCA guidance call for even faster
strengthening than shown in this initial forecast.


Key Messages:
1. Heavy rainfall associated with Tropical Depression 17-E will
impact coastal portions of southwest Mexico this week. This rainfall
may produce life-threatening flooding and mudslides, especially in
areas of steep terrain.

2. Tropical Depression 17-E is forecast to strengthen and move
closer to the southwestern Mexican coast as a major hurricane later
this week. Although it is too soon to determine the exact location
or magnitude of impacts associated with the system, interest in
Mexico should closely monitor its progress and updates to the
forecast.



FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 14.9N 104.9W   30 KT  35 MPH
 12H  21/0600Z 15.2N 104.2W   40 KT  45 MPH
 24H  21/1800Z 15.3N 103.2W   55 KT  65 MPH
 36H  22/0600Z 15.2N 102.6W   70 KT  80 MPH
 48H  22/1800Z 15.1N 102.1W   85 KT 100 MPH
 60H  23/0600Z 15.5N 102.2W   95 KT 110 MPH
 72H  23/1800Z 16.4N 103.0W  100 KT 115 MPH
 96H  24/1800Z 18.1N 104.9W  100 KT 115 MPH
120H  25/1800Z 19.3N 107.4W  100 KT 115 MPH

$$
Forecaster Pasch