Tropical Storm Ileana Forecast Discussion

124 
WTPZ44 KNHC 130836
TCDEP4

Tropical Storm Ileana Discussion Number   4
NWS National Hurricane Center Miami FL       EP092024
200 AM MST Fri Sep 13 2024

Recent passive microwave images of Ileana reveal a small area of 
deep convection near the center of the storm, and as a result Ileana 
has maintained a cold central dense overcast overnight. However, the 
sharp edge to the cloud pattern suggests some south-southeasterly 
shear is impinging on the storm. Radar data from Los Cabos show 
outer rainbands are spreading across the southern portion of the 
Baja California peninsula. The initial intensity is held at 40 kt 
for this advisory, which is consistent with recent scatterometer 
data that showed several tropical-storm-force wind vectors in the 
southeastern quadrant of the storm. 

The estimated initial motion of Ileana is north-northwestward at 
330/9 kt. The storm is expected to remain on this general heading in 
the near term, bringing the center across the southern portion of 
the Baja California peninsula later today and into the southern Gulf 
of California by early Saturday. Then, a slower northward to 
north-northwestward motion is forecast over the weekend. Little 
change was made to the updated NHC track forecast, which remains 
between the TVCE and HCCA aids.

The structure of Ileana in microwave and radar imagery does not 
suggest much, if any, strengthening is likely before the storm 
reaches the coast of Baja California Sur. Deep-layer wind shear is 
forecast to substantially increase thereafter, and land interaction 
along with potential intrusions of dry air should induce weakening 
through the weekend. The increasingly hostile environmental 
conditions will likely make it difficult for Ileana to sustain 
organized deep convection while it moves northward over the Gulf of 
California. Thus, the updated NHC forecast shows degeneration to a 
remnant low at 48 h and dissipation by 72 h.

Key Messages:

1. Tropical Storm Ileana will bring heavy rainfall to portions of 
western Mexico and southern Baja California Sur through this 
weekend. This heavy rainfall will bring a risk of flash flooding 
and mudslides to portions of the area. 

2. Tropical storm conditions are expected to begin in portions of
Baja California Sur later this morning, where Tropical Storm 
Warnings are in effect.


FORECAST POSITIONS AND MAX WINDS

INIT  13/0900Z 21.5N 108.9W   40 KT  45 MPH
 12H  13/1800Z 22.8N 109.5W   40 KT  45 MPH
 24H  14/0600Z 24.2N 109.9W   35 KT  40 MPH
 36H  14/1800Z 25.3N 110.0W   35 KT  40 MPH
 48H  15/0600Z 26.2N 110.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 60H  15/1800Z 27.1N 110.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  16/0600Z...DISSIPATED

$$
Forecaster Reinhart