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HURRICANE JIMENA DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132015
200 AM PDT MON AUG 31 2015

Jimena has maintained a symmetric very cold CDO with a well-defined
25 n mi diameter eye.  A 0307Z SSMIS pass indicated that a
concentric eyewall structure was in place with a secondary eyewall
located about 30-40 n mi from the center.  A blend of subjective
TAFB and SAB Dvorak classifications along with UW-CIMSS Advanced
Dvorak Technique are the basis for Jimena's 130-kt intensity.

Currently, Jimena is over warm 28 deg C water and is embedded in
weak northerly vertical shear conditions.  While these should favor
continuing an extreme intensity, the mid-level moisture is somewhat
dry and the atmosphere not very unstable for deep convection. During
the next few days, the SSTs should gradually cool while the vertical
shear should gradually increase as Jimena moves west-northwestward.
Complicating the forecast is the possibility that Jimena may undergo
another concentric eyewall cycle, with short-term weakening followed
by possible reintensification. However, such variations are
difficult to precisely predict. The intensity forecast is nearly the
same as from the previous advisory and is closest to the statistical
SHIPS model from 12 to 36 hours, and is close to the IVCN consensus
technique thereafter.

Jimena is moving quickly toward the west-northwest at 15 kt,
primarily through the steering induced by a deep-layer ridge to its
north.  The ridge should weaken and become oriented
northwest-to-southeast during the next couple of days.  This should
result in Jimena turning toward the northwest at a slower rate of
speed. The forecast track is nearly identical to the previous
advisory and is based upon the very tightly packed consensus of the
skillful dynamical models.

Jimena's wind radii were significantly adjusted outward based upon
an 0216Z CIRA AMSU pass and an 0536Z partial ASCAT pass.

FORECAST POSITIONS AND MAX WINDS

INIT  31/0900Z 15.3N 133.9W  130 KT 150 MPH
 12H  31/1800Z 15.7N 135.9W  125 KT 145 MPH
 24H  01/0600Z 16.3N 137.9W  120 KT 140 MPH
 36H  01/1800Z 16.9N 139.4W  110 KT 125 MPH
 48H  02/0600Z 17.5N 140.5W  100 KT 115 MPH
 72H  03/0600Z 18.5N 142.0W   90 KT 105 MPH
 96H  04/0600Z 19.5N 143.0W   80 KT  90 MPH
120H  05/0600Z 20.5N 144.0W   70 KT  80 MPH

$$
Forecaster Landsea

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