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Hurricane Estelle Discussion Number  15
NWS National Hurricane Center Miami FL       EP062022
900 PM MDT Mon Jul 18 2022
 
Estelle's structure has continued to go downhill this afternoon and 
evening. While upper-level outflow is fanning out westward ahead of 
the hurricane, last light visible satellite imagery continues to 
indicate that the low-level center remains displaced to the 
northwest of the coldest cloud tops. In fact, an earlier AMSR2 
microwave pass at 2057 UTC showed increasing separation between the 
low-level center on the 37-GHz channel and the mid-level center on 
the 89-GHz channel. This southeast tilt with height also appears to 
be captured well on the most recent HWRF run, and is likely the 
result of continued northwesterly shear undercutting the outflow 
layer, helping import dry stable air into Estelle's core. Satellite 
intensity estimates have been gradually decreasing, though an 
earlier ASCAT-C pass at 1722 UTC still showed peak winds of 61-kt in 
the northeast quadrant of the circulation. Assuming some 
undersampling, the initial intensity is lowered to only 65 kt this 
advisory, though this could be generous.
 
It seems that Estelle's time left to intensify has run out. In fact, 
the hurricane has already been gradually weakening over the past day 
or so. While the current moderate northwesterly shear is expected to 
subside some over the next 24 hours, the cyclone will be moving over 
sub 26 C sea-surface temperatures (SSTs) by that time span. Thus, 
the latest intensity forecast now shows Estelle gradually weakening 
over the next 24-48 hours, with more pronounced weakening thereafter 
when SSTs drop below 23 C. Simulated IR brightness temperature data 
from the ECMWF and CMC models suggest Estelle will cease to produce 
organized deep convection by 72 hours, and the system is forecast to 
become a post-tropical remnant low by then. The latest NHC intensity 
forecast is now more in line with the intensity guidance consensus, 
though early on favors a blend of the HWRF/HMON forecasts, which 
appear to be correctly capturing the current tilted structure of the 
cyclone well.
 
Estelle has been taking a slight leftward bend in its recent track, 
but in general has maintained a west-northwestward heading at 285/12 
kt. A prominent mid-level ridge located to the northeast of Estelle 
should maintain the cyclone on a west-northwest heading at a similar 
motion for the next 2-3 days. Thereafter, as the system becomes more 
vertically shallow, its track is forecast to bend back westward as 
it becomes more steered by the low-level easterly trade winds. The 
latest track forecast is very close to the prior forecast, taking a 
blend of the consensus aids HCCA and TVCE.
 
Estelle is expected to continue producing rough surf and rip current
conditions along the coast of southwestern and west-central Mexico
as well as the southern tip of the Baja California peninsula during
the next day or so.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/0300Z 18.3N 113.6W   65 KT  75 MPH
 12H  19/1200Z 18.7N 115.3W   60 KT  70 MPH
 24H  20/0000Z 19.4N 117.5W   55 KT  65 MPH
 36H  20/1200Z 20.3N 119.8W   55 KT  65 MPH
 48H  21/0000Z 21.3N 122.0W   50 KT  60 MPH
 60H  21/1200Z 22.1N 124.0W   40 KT  45 MPH
 72H  22/0000Z 22.8N 125.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  23/0000Z 23.3N 128.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  24/0000Z 23.0N 131.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 
$$
Forecaster Papin
 
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