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Tropical Storm Madeline Discussion Number   4
NWS National Hurricane Center Miami FL       EP142022
900 AM MDT Sun Sep 18 2022
 
A large burst of deep convection has developed southwest of 
Madeline's center during the past few hours, with another broken 
line of convection oriented parallel to the southwestern coast of 
Mexico.  The current intensity remains 40 kt as a blend of the 
latest Dvorak Current Intensity numbers from TAFB and SAB, and the 
latest UW-CIMSS SATCON estimate.

Madeline is located along the southwestern periphery of a large 
mid-tropospheric high, and to the southeast of a deep-layer trough 
to the west of California.  The initial motion is northward, or 
350/9 kt, but this steering set up should cause Madeline to 
gradually turn northwestward later today, and then 
west-northwestward and westward away from the coast of Mexico from 
36 hours and beyond.  The track guidance is tightly clustered 
through 48 hours, but there is more spread after that, with a few 
models keeping Madeline too strong and maintaining a northwestward 
motion.  These models are discounted, and the official forecast 
continues to show a westward bend, following the GFS, ECMWF, and 
model consensus solutions.

Madeline's broad circulation, and continued moderate to strong 
easterly shear, argue against much, if any, intensification during 
the next day or so.  The official forecast still allows for the 
possibility for some minimal strengthening during the next 24 hours 
while Madeline is over warm waters.  After 24 hours, the storm is 
forecast to begin moving across the cold wake left behind by former 
Hurricane Kay, which is expected to induce weakening.  The updated 
NHC intensity forecast is a little lower than the previous 
prediction, and it now shows Madeline degenerating into a 
post-tropical remnant low by 60 hours, when model simulated 
satellite imagery from the GFS and ECMWF indicate that all deep 
convection should have dissipated.

 
KEY MESSAGES:
 
1. Heavy rains from Madeline are expected for portions of coastal
southwestern Mexico into Monday.  This rainfall may produce flash 
and urban flooding, along with possible mudslides in areas of higher
coastal terrain.
 
2. Tropical storm conditions are possible for the southwestern
coast of Mexico from Manzanillo to Cabo Corrientes today and 
tonight.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/1500Z 18.5N 106.9W   40 KT  45 MPH
 12H  19/0000Z 19.5N 107.6W   40 KT  45 MPH
 24H  19/1200Z 20.4N 108.8W   45 KT  50 MPH
 36H  20/0000Z 21.0N 110.1W   40 KT  45 MPH
 48H  20/1200Z 21.3N 111.3W   35 KT  40 MPH
 60H  21/0000Z 21.5N 112.4W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  21/1200Z 21.6N 113.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  22/1200Z 21.4N 116.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  23/1200Z 21.1N 119.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Berg
 
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