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Tropical Storm Eugene Discussion Number   3
NWS National Hurricane Center Miami FL       EP062023
900 PM MDT Sat Aug 05 2023
 
Eugene has strengthened this evening. Deep convection has increased 
near and over the center of the system during the past several 
hours, with more pronounced convective banding over the southeastern 
portion of the circulation. Additionally, earlier AMSR2 and SSMIS 
passive microwave data showed some evidence of a formative inner 
core trying to take shape. The various 00 UTC objective and 
subjective satellite intensity estimates ranged from 35-55 kt. Given 
the overall improved convective structure of Eugene, the initial 
intensity is raised to 45 kt based on a blend of these data. 

The tropical storm has a brief window to intensity over very warm 
(29-30C) SSTs before the environment becomes increasingly hostile. 
Deep-layer shear is forecast to strengthen later on Sunday, and soon 
thereafter Eugene will encounter a drier and more stable airmass 
while moving over progressively cooler SSTs. The updated NHC 
intensity forecast shows a slightly higher peak (55 kt) in 12-24 h 
that is supported by the latest intensity consensus aids, followed 
by steady weakening through early next week. Eugene could become 
completely devoid of convection in 60 h based on simulated satellite 
imagery from the global and hurricane models. Therefore, the NHC 
forecast shows Eugene degenerating to a remnant low early Tuesday 
and dissipating by the end of the forecast period.

The initial motion remains northwestward at 310/13 kt. Eugene is 
expected to turn west-northwestward over the next day or two while 
being steered by a mid-level ridge to its north. Later in the 
forecast period, a shortwave trough approaching the U.S. West Coast 
will produce a break in the subtropical ridge. This will result in 
weaker steering currents that should cause the shallow cyclone to 
slow down before eventually turning more northward and dissipating 
over cooler waters. The updated NHC forecast shows a slightly faster 
forward speed in agreement with the latest HCCA and TVCE aids, but 
otherwise is very similar to the previous issuance. While the risk 
of tropical-storm-force winds for the southern portion of the Baja 
California peninsula remains low based on this forecast, interests 
there should continue to monitor the progress of this system.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  06/0300Z 20.0N 108.8W   45 KT  50 MPH
 12H  06/1200Z 21.4N 110.8W   55 KT  65 MPH
 24H  07/0000Z 22.8N 113.7W   55 KT  65 MPH
 36H  07/1200Z 24.1N 116.9W   45 KT  50 MPH
 48H  08/0000Z 25.2N 119.5W   35 KT  40 MPH
 60H  08/1200Z 26.0N 121.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  09/0000Z 26.7N 121.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  10/0000Z 28.4N 120.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  11/0000Z...DISSIPATED
 
$$
Forecaster Reinhart
 
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