[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 120831
TCDAT4

Subtropical Storm Melissa Discussion Number   4
NWS National Hurricane Center Miami FL       AL142019
500 AM AST Sat Oct 12 2019

Deep convection has increased a little near the center of Melissa
during the past few hours, likely because it has moved over the
warmer waters of the Gulf Stream current.  However, convection is
quite limited elsewhere.  An ASCAT-B pass from several hours ago
showed maximum winds of about 40 kt in the northwestern quadrant.
However, this pass did not completely capture the entire
circulation, so the initial intensity is held at 45 kt given that
stronger winds could exist in the regions not sampled.  This
intensity estimate is also in fair agreement with the latest
satellite estimates as well.

Melissa is expected to resume weakening later today due to a
combination of an increase in westerly wind shear and intrusions of
dry air.  The cyclone will likely degenerate to a remnant low in
about 24 hours when the system is forecast to be over SSTs of 23 to
24 C. The remnant low is expected to linger for at least a couple of
days before it is absorbed within a frontal zone over the north
Atlantic.  The NHC intensity forecast is in best agreement with the
GFS, UKMET, and ECMWF global models.

The subtropical storm has turned northeastward during the last
several hours, with the initial motion estimated to be 055/6
kt.  The weakening system is expected to become more embedded in
the mid-latitude westerlies during the next few days, and as a
result, a turn to the east-northeast with an increase in forward
speed is forecast, taking the cyclone away from the Mid-Atlantic and
northeast U.S. coastline.  The NHC track forecast is adjusted a
little to the north of the previous one to be in better agreement
with the latest model runs.

Ongoing hazards from wind and coastal flooding will continue to be
covered by non-tropical products from local National Weather Service
forecast offices.

Gale-force winds that extend from Nova Scotia eastward over the
Atlantic are not included in the wind radii, since they are
associated with a frontal boundary.

Key Messages:

1. Melissa is expected to slowly weaken and move away from the
U.S. east coast today, resulting in a gradual decrease in wind and
coastal flooding impacts.

2. Minor to moderate coastal flooding is still expected along
portions of the U.S. Mid-Atlantic and southeastern New England
coasts around times of high tide today.  For more information,
see products issued by local National Weather Service forecast
offices at weather.gov.


FORECAST POSITIONS AND MAX WINDS

INIT  12/0900Z 38.1N  68.2W   45 KT  50 MPH
 12H  12/1800Z 38.4N  66.7W   40 KT  45 MPH
 24H  13/0600Z 39.0N  63.8W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  13/1800Z 39.6N  60.4W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  14/0600Z 40.3N  56.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  15/0600Z 41.6N  47.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  16/0600Z...ABSORBED WITHIN A FRONTAL ZONE

$$
Forecaster Cangialosi
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