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HURRICANE JIMENA DISCUSSION NUMBER  21
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP132015
200 PM PDT MON AUG 31 2015

Jimena continues to exhibit a concentric eyewall structure around a
20 n mi diameter eye.  The cloud tops have warmed a little during
the past few hours, and the overall satellite presentation is not
quite as impressive as it was several hours ago.  The Dvorak Final
T-numbers from TAFB and SAB have decreased slightly, and the initial
wind speed is lowered a little to 125 kt.

The hurricane is still moving westward at about 14 kt, which is a
little faster than previously predicted.  A mid-level high pressure
system located to the north of the tropical cyclone should continue
to steer Jimena west-northwestward in the short term, but this ridge
is expected to weaken during the next day or two in response to an
amplification of a mid- to upper- level trough extending
southwestward from the western United States. This pattern change
should cause the steering currents around Jimena to weaken,
resulting in a gradual northwestward turn with a dramatic decrease
in forward speed after 48 hours. The track model guidance has
shifted a little to the left and is slightly faster than earlier,
and the new NHC track forecast follows that theme.

Jimena is likely to fluctuate in intensity during the next 12 to 24
hours while it remains embedded in a very low wind shear environment
and over 28 deg C waters.  After that time, a slow weakening is
expected while SSTs decrease along the forecast track.  The NHC
intensity forecast is just an update of the previous one and remains
on the high side of the intensity guidance, giving some weight to
the global models which maintain a very strong cyclone for the next
several days.

FORECAST POSITIONS AND MAX WINDS

INIT  31/2100Z 15.9N 136.8W  125 KT 145 MPH
 12H  01/0600Z 16.4N 138.4W  125 KT 145 MPH
 24H  01/1800Z 17.1N 140.1W  120 KT 140 MPH
 36H  02/0600Z 17.6N 141.2W  110 KT 125 MPH
 48H  02/1800Z 18.2N 142.1W  100 KT 115 MPH
 72H  03/1800Z 19.2N 143.2W   90 KT 105 MPH
 96H  04/1800Z 20.2N 144.0W   80 KT  90 MPH
120H  05/1800Z 21.6N 144.7W   70 KT  80 MPH

$$
Forecaster Cangialosi

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