050
WTPZ41 KNHC 200848
TCDEP1

Tropical Storm Odalys Discussion Number   1
NWS National Hurricane Center Miami FL       EP162026
200 AM PDT Sun Sep 20 2026

Satellite imagery indicates that the convective organization of
Odalys has improved over the past several hours. Deep convection
continues to develop within a band wrapping around the western and
southern semicircles, with a recent burst of convection expanding
over or near the circulation center. The latest subjective Dvorak
intensity estimate from TAFB is T2.5/35 kt. Given these data and the
improved satellite presentation, advisories are being initiated on
newly formed Tropical Storm Odalys, with an initial intensity of 35
kt.

The initial motion is estimated to be northwestward, or 305/7 kt.
This general motion is expected to continue during the next day or
two as a low- to mid-level subtropical ridge remains positioned to
the north. Thereafter, Odalys is forecast to slow considerably and
turn sharply eastward by Tuesday, then east-northeastward through
the latter part of the week in response to a developing weakness in
the ridge as an upper-level trough deepens over the western United
States. Although the track guidance remains in decent agreement
through the first half of the week, increasing cross-track spread
develops thereafter. This appears to be due, at least in part, to
differences in how the models handle the evolution of the
upper-level trough over the western United States and the potential
influence of another developing tropical cyclone tracking
west-northwestward offshore of southwestern Mexico. These factors
lead to lower confidence in the track forecast during the latter
portion of the forecast period. The NHC track forecast closely
follows the HCCA and GDMI aids through around day 4, then reflects
more of a blend of the two thereafter as the spread increases.

Environmental conditions appear favorable for gradual strengthening
during the next couple of days, with warm sea surface temperatures
and plenty of deep moisture expected along the forecast track.
However, modest north-northeasterly vertical wind shear may temper
the rate of intensification during the next 24 h. Thereafter, the
rate of strengthening could increase as the shear relaxes and Odalys
remains in a favorable environment. The NHC forecast has the system
becoming a hurricane by Monday, with some additional strengthening
possible through Tuesday. Thereafter, progressively drier mid-level
air, along with increasing vertical wind shear anticipated later in
the forecast period, should induce a steady weakening trend. There
is additional uncertainty in the intensity forecast due to the
potential influence of another tropical cyclone evolving well to the
east, which could affect its intensity depending on the eventual
tracks and proximity of the two systems late in the week. The NHC
intensity forecast lies near the middle to upper end of the guidance
envelope through much of the period.


FORECAST POSITIONS AND MAX WINDS

INIT  20/0900Z 11.4N 124.5W   35 KT  40 MPH
 12H  20/1800Z 12.0N 125.6W   45 KT  50 MPH
 24H  21/0600Z 13.3N 127.1W   55 KT  65 MPH
 36H  21/1800Z 14.4N 128.3W   65 KT  75 MPH
 48H  22/0600Z 15.0N 128.9W   70 KT  80 MPH
 60H  22/1800Z 15.2N 128.7W   70 KT  80 MPH
 72H  23/0600Z 15.3N 128.0W   65 KT  75 MPH
 96H  24/0600Z 15.6N 126.5W   65 KT  75 MPH
120H  25/0600Z 16.7N 124.8W   65 KT  75 MPH

$$
Forecaster Gibbs