Official Discussion issued by the National Hurricane Center

Jose (AL122017) DATA RELEASED: 9/20/2017 3:00:00 PM UTC

Copy of official data

Tropical Storm Jose Discussion Number  61
NWS National Hurricane Center Miami FL       AL122017
1100 AM EDT Wed Sep 20 2017

The Air Force Hurricane Hunters have been investigating Jose this
morning and found maximum flight-level winds of 78 kt at 5,000 feet
and peak SFMR surface winds of 56 kt.  Based on these data, the
initial wind speed is set at 60 kt, which is slightly higher than
the previous estimate.  Jose remains a sprawling cyclone, with
tropical storm force winds extending 180 n mi from the center.
Although Jose does not have a purely tropical appearance, it still
has a warm core and well-defined convective bands, especially to the
north of the center.

Jose is moving northeastward at 7 kt toward a mid- to upper-level
trough over eastern Canada.  A slightly slower northeastward to
east-northeastward motion is expected through tonight.  Thereafter,
the trough is expected to lift out, allowing a mid-level high
pressure system to build to the northwest of Jose.  This will likely
cause the storm to reverse its course and drift westward or
west-southwestward.  In about 3 days, however, the models suggest
that Jose will be caught in very weak steering currents, and the NHC
official track forecast now shows Jose stationary from 72 to 120
hours.

The tropical storm is moving over a tight SST gradient associated
with the north wall of the Gulf Stream current, and it will likely
remain over this gradient for the next several days.  These
relatively cool SSTs and dry air should cause a slow weakening
trend, and a gradual transition to a post-tropical cyclone.  The NHC
intensity forecast is not too different from the previous one and is
in best agreement with the consensus models.

KEY MESSAGES:

1. While the center of Jose is forecast to remain offshore of the
U.S. east coast, the large cyclone is expected to cause some direct
impacts in portions of New England during the next couple of days,
and a tropical storm warning is in effect for Cape Cod, Block
Island, Martha's Vineyard, and Nantucket.

2. Minor to moderate coastal flooding is possible from Delaware to
southern New England during the next several days.  Please see
products issued by local National Weather Service forecast offices.

3. Swells generated by Jose are affecting Bermuda and much of the
U.S. east coast and will likely cause dangerous surf and rip current
conditions for the next several days in these areas.

4. Jose is expected to produce additional rainfall accumulations of
1 to 2 inches over Martha's Vineyard and Cape Cod, and 2 to 4 inches
in Nantucket as it passes offshore today into Thursday.  This
rainfall could cause isolated flash flooding.

FORECAST POSITIONS AND MAX WINDS

INIT  20/1500Z 39.0N  70.0W   60 KT  70 MPH
12H  21/0000Z 39.5N  69.0W   60 KT  70 MPH
24H  21/1200Z 39.8N  68.1W   55 KT  65 MPH
36H  22/0000Z 39.6N  68.3W   45 KT  50 MPH
48H  22/1200Z 39.5N  69.0W   40 KT  45 MPH...POST-TROPICAL
72H  23/1200Z 39.3N  70.0W   40 KT  45 MPH...POST-TROPICAL
96H  24/1200Z 39.3N  70.0W   35 KT  40 MPH...POST-TROPICAL
120H  25/1200Z 39.3N  70.0W   30 KT  35 MPH...POST-TROPICAL

$$
Forecaster Cangialosi