Tropical Storm Emilia Forecast Discussion

000
WTPZ45 KNHC 050253
TCDEP5

Tropical Storm Emilia Discussion Number   3
NWS National Hurricane Center Miami FL       EP052024
800 PM MST Sun Aug 04 2024

The organization of the tropical cyclone has improved on satellite 
imagery since the previous advisory.  The subjective CI numbers from 
TAFB and SAB are both T-2.5/35 kt, and the CIMSS objective intensity 
estimates range from 33 to 35 kt.  Earlier ASCAT data from around 17 
UTC had peak wind vectors of 31 kt, and the organization on 
satellite imagery has certainty improved since that time, with the 
cyclone becoming more compact.  Based on the Dvorak estimates, the 
depression is upgraded to Tropical Storm Emilia with an initial 
intensity of 35 kt.

The track forecast for Emilia is very dependent on a disturbance to 
the east of the system (Invest 96E), which has a high chance of 
becoming a tropical cyclone over the next day or so. Most of the 
global models show both systems interacting with and rotating 
cyclonically around each other.  Emilia should move to the 
south-southwest for the next 24 h, while it is located to the west 
of 96E.  After that time, the larger circulation of 96E should pull 
the smaller Emilia toward the northwest or north-northwest.  Only 
minor changes were made to the previous NHC track forecast.  96E 
and Emilia should merge together into one cyclone over the next 
couple of days, but it is uncertain which cyclone will be dominant 
and which cyclone will be absorbed.  This forecast assumes that 96E 
will absorb Emilia, with Emilia dissipating beyond 48 h.  However, 
it is quite possible that the opposite occurs, with Emilia absorbing 
96E.  Either way, I expect a tropical cyclone (the merged system) to 
be moving west-northwestward in 3 to 4 days, spreading tropical 
storm conditions across the open waters of the Pacific.  The ECMWF 
model shows the two systems merging in 36-48 h, but the latest GFS 
model predicts a longer binary interaction, with the merger 
occurring in 3 to 4 days.  

Until the disturbance to the east starts to interact with Emilia, 
the environment appears favorable for intensification, and the 
intensity guidance has trended upward this cycle.  The new NHC 
forecast shows Emilia strengthening to a 55 kt tropical storm in 36 
h.  This is near, or slightly below the middle of the intensity 
guidance envelope.  The thinking is that Emilia will merge with 96E 
after that time, and 96E will likely be a tropical storm at the 
time of the merger.


FORECAST POSITIONS AND MAX WINDS

INIT  05/0300Z 15.0N 113.2W   35 KT  40 MPH
 12H  05/1200Z 14.2N 113.4W   40 KT  45 MPH
 24H  06/0000Z 13.8N 113.5W   50 KT  60 MPH
 36H  06/1200Z 14.3N 113.8W   55 KT  65 MPH
 48H  07/0000Z 15.6N 114.8W   55 KT  65 MPH
 60H  07/1200Z...DISSIPATED

$$
Forecaster Hagen/Roberts