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HURRICANE JIMENA DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132015
200 PM PDT SAT AUG 29 2015

Recent microwave imagery continued to show Jimena's eyewall nearly
enclosed by a larger outer ring of convection, signaling that
concentric eyewalls may be developing.  A moat region is also
evident in the latest visible images.  Cloud tops have gradually
warmed since this morning, and Jimena appears to have weakened a
little.  The initial intensity is set at 120 kt based on a blend of
CI numbers of 6.0/115 from TAFB, 6.5/127 kt from SAB, and 6.3/122
kt from the CIMSS ADT.

Jimena may be in the early stages of an eyewall replacement, which
makes the short-term intensity forecast a little tricky.  The
overall environment remains conducive for strengthening, so if an
eyewall replacement occurs, the hurricane has an opportunity to
re-intensify during the next day or so.  The bottom line is that
fluctuations in intensity are likely during the next 24-48 hours,
and Jimena is expected to remain a major hurricane during that
time.  After 48 hours, gradual weakening is indicated in the
forecast, with the most likely reason being lower oceanic heat
content.  The hurricane models continue to show a much faster
weakening rate than the global models, and as a compromise, the
updated NHC intensity forecast lies near the upper end of the
typically skillful models.  This solution is closest to the SHIPS
model.

Jimena has turned west-northwestward with an initial motion of
285/8 kt.  The subtropical ridge north of the hurricane is
weakening, and Jimena is expected to continue moving toward the
west-northwest through day 5.  However, the cyclone should slow down
considerably by days 4 and 5 due to weakening steering currents.
The track guidance has continued to trend faster, and the updated
NHC track forecast is again a little bit ahead of the previous
forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 12.8N 126.4W  120 KT 140 MPH
 12H  30/0600Z 13.4N 128.1W  125 KT 145 MPH
 24H  30/1800Z 14.2N 130.4W  120 KT 140 MPH
 36H  31/0600Z 15.0N 133.0W  115 KT 130 MPH
 48H  31/1800Z 15.6N 135.4W  110 KT 125 MPH
 72H  01/1800Z 16.6N 139.1W  105 KT 120 MPH
 96H  02/1800Z 17.4N 141.3W   95 KT 110 MPH
120H  03/1800Z 18.0N 142.7W   85 KT 100 MPH

$$
Forecaster Berg

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