Official Discussion issued by the National Hurricane Center

Jose (AL122017) DATA RELEASED: 9/10/2017 5:00:00 AM UTC

Copy of official data

Hurricane Jose Discussion Number  20
NWS National Hurricane Center Miami FL       AL122017
Issued by the NWS Weather Prediction Center College Park MD
500 AM AST Sun Sep 10 2017

Jose remains a category four hurricane on the Saffir-Simpson
Hurricane Wind Scale, with a 15 n mi wide eye continuing to be
surrounded a solid ring of deep convection. Little significant
change in the overall satellite appearance has been observed since a
Hurricane Hunter plane sampled the cyclone earlier in the night, and
the initial intensity remains unchanged at 115 kt.

The initial motion is 310/14 kt, with Jose's track through the first
24 hours being driven by a mid-level ridge located to the
north-northeast of the cyclone. After this time, the steering
pattern is expected to become rather dynamic, leading to a
5-day forecast that shows Jose making a small anticyclonic loop
over the open waters of the western Atlantic. This occurs as the
ridge shifts to the east of Jose from 36 to 48 hours, leading to a
reduction in forward speed, and a gradual turn toward the north. A
turn toward the east and southeast is expected on days 3 and 4, with
an even slower forward motion, as the ridge weakens and moves south
of the system. Late in the forecast period, the ridge is expected to
build to the northwest and then north of Jose, leading to a gradual
acceleration toward the west, and a reduction in the shear. With
such a complex steering pattern expected, it comes as no surprise
that the track guidance diverges significantly in the latter
forecast periods. The updated forecast is close to the previous one,
lies close to the FSSE, and is in between the GFS and ECMWF, which
are more than 250 miles apart on day 5.

The shear over Jose is currently analyzed to be near 10 kt, but
north to northeasterly shear is forecast to increase in the short
term and remain relatively strong through 48 hours due to Jose
moving closer to a building ridge to its northwest. This will
lead to a weakening trend, despite the system remaining over SSTs
near 29 Celsius. The official intensity forecast is nudged down ever
so slightly from the previous one through day 3, but remains higher
than the SHIPS model, due to the ECMWF and GFS models maintaining a
more intense system. The intensity prediction on days 4 and 5
remains unchanged due to forecast environmental uncertainties at
that time.


FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 20.8N  64.5W  115 KT 130 MPH
12H  10/1800Z 22.2N  66.1W  110 KT 125 MPH
24H  11/0600Z 24.2N  67.9W  105 KT 120 MPH
36H  11/1800Z 25.6N  69.0W  100 KT 115 MPH
48H  12/0600Z 26.5N  68.8W   95 KT 110 MPH
72H  13/0600Z 26.3N  67.0W   90 KT 105 MPH
96H  14/0600Z 25.0N  66.5W   90 KT 105 MPH
120H  15/0600Z 24.5N  70.0W   90 KT 105 MPH

$$
Forecaster Birchard/Blake