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Hurricane Norman Discussion Number 16
NWS National Hurricane Center Miami FL EP162018
800 PM PDT Fri Aug 31 2018
Several recent microwave passes indicate that Norman continues to
feel the effects of northeasterly shear, with the cyclone vertically
titled and its upper-level core disrupted in the northern
semicircle. Furthermore, the eye of the hurricane has disappeared
on IR and visible imagery. Satellite intensity estimates from
TAFB and SAB have also decreased since the previous advisory, and
therefore, the initial intensity has been decreased to 105 kt, and
this value could be a little generous.
Model guidance continues to indicate moderate northeasterly shear
over the cyclone for the next day or so, which should cause
the gradual weakening to continue. Thereafter, the shear is
forecast to lessen somewhat, but the cyclone is expected to begin
entraining dry air from its surrounding environment. There may be
some time between 24-48 hours when the lessening shear and warm SSTs
could overcome the drier air in the environment to allow for either
a steadying of intensity or perhaps even some slight
re-strengthening. Beyond 48 hours, however, the environment is
forecast to become even drier, which should induce another weakening
trend. The NHC intensity forecast has been changed little through 24
h, but now shows a leveling off of the intensity from 24-48 h.
Steady weakening is still anticipated beyond that time.
The initial motion is estimated to be west-southwest, or 250/7 kt.
Mid- to upper-level ridging that extends west-southwestward from
the Baja California peninsula to just northwest of the cyclone
should steer Norman west-southwestward for the next several hours.
By Saturday morning, the ridge should begin to become oriented more
east-to-west then southeast-to-northwest by Sunday. This will cause
the system to be steered on a more westward then west-northwestward
track with an increase in forward speed over the weekend and into
early next week. The NHC track forecast has been shifted slightly
left and is a little faster than the previous advisory. This
forecast is generally between the previous NHC forecast and the
consensus guidance track. Based on this forecast, Norman is
expected to move into the central Pacific basin by Tuesday.
FORECAST POSITIONS AND MAX WINDS
INIT 01/0300Z 16.3N 122.2W 105 KT 120 MPH
12H 01/1200Z 16.2N 123.6W 95 KT 110 MPH
24H 02/0000Z 16.4N 125.9W 90 KT 105 MPH
36H 02/1200Z 17.0N 128.7W 90 KT 105 MPH
48H 03/0000Z 17.7N 131.8W 90 KT 105 MPH
72H 04/0000Z 19.1N 138.0W 80 KT 90 MPH
96H 05/0000Z 20.3N 142.7W 70 KT 80 MPH
120H 06/0000Z 21.2N 146.3W 65 KT 75 MPH