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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
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