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HURRICANE JIMENA DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132015
200 AM PDT SUN AUG 30 2015

The overall cloud pattern has degraded a little during the past few
hours with some cooling of the eye of Jimena.  Microwave data
confirm the ongoing eyewall replacement, with some evidence that the
inner eyewall is eroding at the expense of an outer eyewall.
Satellite estimates have come down somewhat, so the initial
intensity is reduced to 115 kt.

The intensity forecast for the next day or so is primarily dependent
on when and if the eyewall cycle completes. After considering the
low-shear, warm-water environment, I will assume that Jimena will be
able to complete the eyewall cycle and not lose much more intensity
this weekend. After that time, overall environmental conditions only
gradually become less conducive. These factors suggest a slow decay
of the cyclone then, although there is considerable uncertainty
since the intensity guidance is rather divergent by long range.
There has not been any significant change to the intensity
consensus and, given the uncertainties, the new forecast is kept
nearly the same as the old one.

The initial motion estimate is 290/11.  So far Jimena has been a
well-behaved cyclone as the subtropical ridge has provided a steady
steering current.  This ridge is forecast to remain firm for the
next few days, keeping the west-northwestward motion in place.
Around the time Jimena reaches the central Pacific, it should slow
down considerably due to a weakening of the subtropical ridge, which
could allow a turn to the northwest by the end of the period.
However, the bulk of guidance keep the hurricane moving slowly
west-northwestward through day 5, with some outliers.  No
significant changes were made to the latest NHC prediction since the
model consensus is very close to the previous official forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z 13.7N 128.4W  115 KT 130 MPH
 12H  30/1800Z 14.3N 130.1W  115 KT 130 MPH
 24H  31/0600Z 15.1N 132.7W  115 KT 130 MPH
 36H  31/1800Z 15.8N 135.2W  110 KT 125 MPH
 48H  01/0600Z 16.3N 137.3W  105 KT 120 MPH
 72H  02/0600Z 17.2N 140.2W   95 KT 110 MPH
 96H  03/0600Z 17.9N 142.0W   85 KT 100 MPH
120H  04/0600Z 18.5N 143.5W   75 KT  85 MPH

$$
Forecaster Blake

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