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Tropical Storm Jose Discussion Number 60
NWS National Hurricane Center Miami FL AL122017
500 AM EDT Wed Sep 20 2017

Enhanced BD-curve infrared imagery shows considerable decay of yesterday afternoon's burst of deep convection near Jose's center. An earlier GPM low-frequency microwave overpass revealed that the strongest convection and associated winds were located in the north and west periphery of of the cyclone's circulation, a wind pattern indicative of non-tropical systems. Based on the deteriorating cloud pattern and a blend of the latest subjective T-numbers from TAFB and SAB, the initial intensity is lowered to 55 kt. Jose has begun its movement north of the Gulf Stream's north wall and over decreasing oceanic temperatures. Subsequent CIMSS shear analysis and the SHIPS model indicate modest southwesterly shear undercutting the outflow aloft. These inhibiting factors should result in additional weakening, and the official forecast calls for Jose to become a post-tropical cyclone in 48 hours, if not sooner.

The initial motion is estimated to be northeastward, or 040/7 kt. There is no significant change to the previous track forecast or philosophy. The large-scale models continue to agree on Jose decreasing in forward speed and gradually turning toward the east on Thursday morning in response to a mid-tropospheric shortwave trough moving eastward out of the eastern Canadian provinces. Through the remainder of the forecast period, high pressure is expected to build over the northeast U.S. and adjacent waters, causing Jose to drift southward and southwestward through the 72 hour period. After that time, the cyclone is expected to basically meander in the northwest Atlantic within the weak steering flow produced by the aforementioned high pressure to the northwest of the cyclone and a building mid-level ridge to the southeast. The NHC forecast a little slower at days 4 and 5 and closely follows the GFS/ECMWF (GFEX) consensus and the forecast input from NOAA Ocean Prediction Center.



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, 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, the Bahamas, and much of the U.S. east coast. These swells are likely to 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 20/0900Z 38.4N 70.3W 55 KT 65 MPH 12H 20/1800Z 39.1N 69.3W 55 KT 65 MPH 24H 21/0600Z 39.6N 68.1W 50 KT 60 MPH 36H 21/1800Z 39.5N 67.8W 45 KT 50 MPH 48H 22/0600Z 39.2N 68.3W 40 KT 45 MPH...POST-TROPICAL 72H 23/0600Z 38.9N 69.4W 40 KT 45 MPH...POST-TROPICAL 96H 24/0600Z 39.2N 69.5W 35 KT 40 MPH...POST-TROPICAL 120H 25/0600Z 39.5N 68.9W 30 KT 35 MPH...POST-TROPICAL

$$ Forecaster Roberts

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