Tropical Cyclone Discussion

987
WTPZ43 KNHC 290250
TCDEP3
 
Tropical Storm Rachel Discussion Number   8
NWS National Hurricane Center Miami FL       EP182026
900 PM CST Mon Sep 28 2026
 
The satellite-observed structure of Rachel has improved this 
evening. While the storm is still clearly feeling the effects of 
northerly shear, proxy-visible and infrared satellite images show 
the low-level center is tucked underneath the northern side of the 
cold dense overcast. TAFB also noted an improvement in the satellite 
structure of Rachel with their latest T3.0 Dvorak classification, 
and the various UW-CIMSS objective estimates generally range from 
44-54 kt. Based on a blend of these estimates, the initial intensity 
is set at 50 kt.

Rachel is moving west-northwestward (300/9 kt) along the southwest 
side of a mid-level ridge over northern Mexico. A deep-layer trough 
over the southwestern United States is expected to move eastward 
during the next couple of days, which should erode the ridge and 
cause Rachel to turn northwestward at a slower forward speed within 
weaker steering currents through midweek. 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. Overall, the track model guidance trended slightly faster 
this cycle, and the NHC forecast has been adjusted to fall between 
the latest simple (TVCN) and corrected (HCCA) consensus aids.
 
In general, the models agree that Rachel should intensify over very 
warm SSTs (29-30 deg C) with abundant mid-level moisture and a 
divergent upper-level environment. Moderate vertical wind shear 
appears to be the only limiting factor, though it is forecast to 
gradually decrease through midweek. Since the tropical storm is 
sheared and currently lacks an inner core, only gradual 
strengthening is forecast tonight. Thereafter, there is fairly large 
spread in the intensity guidance, with some models including Google 
DeepMind, COAMPS-TC, and HCCA showing Rachel reaching major 
hurricane status. The updated NHC intensity forecast is not as 
aggressive as these models but has been raised from the previous 
prediction, slightly higher than the simple consensus (IVCN) but 
still well below the latest HCCA and GDMI aids. The NHC forecast 
levels off in the 60-120 h time frame based on mixed signals in the 
guidance, perhaps a result of Rachel encountering some cooler waters 
left behind in the wake of Hurricane Polo.
 
 
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 
on Tuesday. Tropical storm conditions are possible in the watch 
area Tuesday night 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 areas 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  29/0300Z 14.5N 102.9W   50 KT  60 MPH
 12H  29/1200Z 15.2N 104.3W   55 KT  65 MPH
 24H  30/0000Z 16.5N 105.8W   65 KT  75 MPH
 36H  30/1200Z 17.9N 107.0W   75 KT  85 MPH
 48H  01/0000Z 18.9N 107.8W   80 KT  90 MPH
 60H  01/1200Z 19.5N 108.5W   85 KT 100 MPH
 72H  02/0000Z 19.9N 109.1W   85 KT 100 MPH
 96H  03/0000Z 20.4N 110.1W   80 KT  90 MPH
120H  04/0000Z 20.9N 111.4W   80 KT  90 MPH