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Tropical Storm Rachel Discussion Number   9
NWS National Hurricane Center Miami FL       EP182026
300 AM CST Tue Sep 29 2026

Rachel has been exhibiting a pattern of bursting very deep 
convection over the past several hours with cloud tops as cold as 
-90 deg C.  However, the deep convective area has a rather 
shapeless appearance on satellite imagery, and is lacking 
convective banding features.  The storm continues to experience 
some north-northeasterly vertical wind shear.  Observations from a 
NOAA Hurricane Hunter Tail Doppler radar research mission indicate 
that the system is becoming more vertically aligned.  Nonetheless, 
since the system's satellite signature indicates arrested 
development, the advisory intensity is held at 50 kt which is a 
little above the latest Dvorak estimate from TAFB.

Blending center position estimates from the NOAA aircraft along 
with geostationary and microwave satellite-base center fixes, the 
motion estimate is 300/10 kt which is about the same as before.  
Rachel should move along the southwestern side of a mid-level ridge 
with a more northwestward motion being induced by a 500 mb cutoff 
low over the southwestern United States during the next few days.  
By late week, the trough is forecast to lift out and the ridge 
should become reestablished to the north, with Rachel expected to 
resume a west-northwestward motion by around 72 hours.  The 
official track forecast is slightly south of the one from the 
previous advisory but on the northern side of the track guidance 
envelope.

Rachel should be moving through a favorable atmospheric 
thermodynamic environment and over generally warm sea surface 
temperatures during the next several days.  Assuming that the 
vertical wind shear does not become too prohibitive, strengthening 
is forecast.  There is a possibility that the system's 
intensification could be slightly inhibited by some cooler waters 
due to the wake of Hurricane Polo.  The official intensity forecast 
is close to the simple intensity model consensus, but the corrected 
consensus guidance is somewhat higher, as noted in the previous 
advisory discussion.

 
Key Messages:
 
1. Although the core of Rachel is forecast to remain offshore of
Mexico, tropical-storm-force winds are expected along a portion of
the coast of southwestern Mexico in the Tropical Storm Warning area
today.  Tropical storm conditions are possible in the watch area 
tonight or on Wednesday.
 
2. Outer bands from Rachel will bring locally heavy rainfall to 
portions of coastal southwest Mexico through Thursday. This rainfall 
may produce areas of flooding and mudslides, especially in regions 
of steep terrain.
 
3. Large waves could produce life-threatening surf and rip current
conditions along portions of the southwestern coast of Mexico during
the next several days.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0900Z 14.7N 104.3W   50 KT  60 MPH
 12H  29/1800Z 15.7N 105.4W   55 KT  65 MPH
 24H  30/0600Z 17.1N 106.8W   65 KT  75 MPH
 36H  30/1800Z 18.4N 108.1W   75 KT  85 MPH
 48H  01/0600Z 19.3N 109.1W   80 KT  90 MPH
 60H  01/1800Z 19.8N 109.7W   85 KT 100 MPH
 72H  02/0600Z 20.2N 110.3W   85 KT 100 MPH
 96H  03/0600Z 20.7N 111.6W   85 KT 100 MPH
120H  04/0600Z 21.1N 113.5W   85 KT 100 MPH
 
$$
Forecaster Pasch
 
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