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HURRICANE ORLENE DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP162016
800 PM PDT MON SEP 12 2016
Orlene's rapid intensification episode has been interrupted.
Satellite imagery indicates some erosion of the cyclone's deep
convection, primarily over the northeastern quadrant of the
circulation. The eye has also become cloud-filled and indistinct.
A 2324 UTC SSM/I overpass suggested that an eyewall replacement is
underway, which could be the reason for the cyclone's somewhat
degraded satellite appearance. The latest satellite classification
from TAFB was T4.5/77kt and the UW-CIMSS ADT is around that value.
A blend of these data with Dvorak CI-numbers yields an initial
intensity estimate of 90 kt.
Orlene has wobbled a little east of due north during the last
several hours, but an estimate of the cyclone's longer-term initial
motion estimate is 360/05. The hurricane is about to enter a col
region, which should result in a northward or north-northwestward
drift during the next 24 hours or so. The subtropical ridge is
expected to re-strengthen in about 2 days, causing Orlene to turn
south of due west with a substantial increase in forward speed. By
120 hours, the model spread begins to widen, with the ECMWF farther
north and slower compared to the faster and more southern GFS. This
difference arises due to the models' handling of a strong mid- to
upper-tropospheric cyclone around 140W. The ECMWF shows this
feature farther south and stronger while the GFS maintains the
subtropical ridge north of Orlene. The NHC track forecast is not
much different than the previous one, but a little slower by day 5
as a result of the increasing track uncertainty.
With an eyewall replacement in progress, Orlene should continue to
slowly weaken. The cyclone will likely not be able to recover
either since it should come to a halt over a region where the
oceanic heat content rapidly drops off. Orlene's slow motion should
induce significant oceanic upwelling, which could accelerate the
rate of weakening during the next day or two. After that time,
the cyclone will encounter an environment of critically low
moisture, which should promote additional slow weakening. The new
NHC intensity forecast is reduced relative to the previous one and
is near the latest multi-model consensus.
FORECAST POSITIONS AND MAX WINDS
INIT 13/0300Z 18.7N 119.1W 90 KT 105 MPH
12H 13/1200Z 19.2N 119.1W 90 KT 105 MPH
24H 14/0000Z 19.7N 119.2W 80 KT 90 MPH
36H 14/1200Z 19.9N 119.7W 70 KT 80 MPH
48H 15/0000Z 19.8N 120.9W 60 KT 70 MPH
72H 16/0000Z 19.3N 125.0W 50 KT 60 MPH
96H 17/0000Z 18.9N 130.2W 45 KT 50 MPH
120H 18/0000Z 19.0N 133.7W 40 KT 45 MPH