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Hurricane Eugene Discussion Number 7
NWS National Hurricane Center Miami FL EP052017
300 AM MDT Sun Jul 09 2017
Although it hasn't cleared out entirely, an eye has persisted
in infrared satellite imagery since the last advisory, and cloud
tops colder than -70C have at times completely encircled the eye.
Subjective Dvorak estimates from TAFB and SAB were T4.5/77 kt and
T5.0/90 kt, respectively, at 0600 UTC, and an average of these
numbers was mirrored by an objective ADT estimate of T4.8/85 kt.
Eugene's rapid intensification phase continues, and the hurricane is
now estimated to be category 2 with 85-kt winds.
Eugene continues on a northwestward trajectory with an initial
motion of 325/7 kt. Mid-tropospheric ridging is expected to remain
anchored over the western United States for a few more days, while
a progressive shortwave trough approaches the coast of California.
This pattern should keep Eugene on a northwestward path for the
entire five-day forecast period, with a faster forward speed
anticipated from 12-36 hours. The track guidance remains tightly
clustered, especially through 72 hours, and the NHC official
forecast has been nudged westward toward the various consensus
models. By the end of the forecast period, the official forecast
favors the weaker, westward-leaning GFS and ECMWF models.
Eugene has blown through all prior intensity guidance, so it's a
little difficult to know how long this period of rapid
intensification will last. The hurricane is expected to remain in
a low-shear environment for much of the forecast period, and it
will continue to traverse waters warmer than 26C for another 24-36
hours. Therefore, continued strengthening is likely, and Eugene
could attain major hurricane intensity before it reaches colder
water. The new NHC intensity forecast has been bumped upward and
continues to be at the upper bound of the intensity models, closest
to the SHIPS guidance through 36 hours. Weakening should be rather
fast after 36 hours as Eugene moves over quickly decreasing sea
surface temperatures, and the global models suggest that the
cyclone will cease producing deep convection by 96 hours. At that
point in the forecast Eugene is expected to be a remnant low.
FORECAST POSITIONS AND MAX WINDS
INIT 09/0900Z 15.2N 114.1W 85 KT 100 MPH
12H 09/1800Z 16.4N 115.1W 100 KT 115 MPH
24H 10/0600Z 18.0N 116.5W 105 KT 120 MPH
36H 10/1800Z 19.5N 117.9W 90 KT 105 MPH
48H 11/0600Z 20.9N 119.2W 75 KT 85 MPH
72H 12/0600Z 23.3N 121.4W 45 KT 50 MPH
96H 13/0600Z 25.0N 123.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 14/0600Z 26.5N 125.5W 20 KT 25 MPH...POST-TROP/REMNT LOW