Tropical Storm Melissa Forecast Discussion Number 8

By | October 13, 2019

Issued at 500 AM AST Sun Oct 13 2019

WTNT44 KNHC 130831
Tropical Storm Melissa Discussion Number   8
NWS National Hurricane Center Miami FL       AL142019
500 AM AST Sun Oct 13 2019
Satellite images indicate that Melissa has lost organization
overnight.  Deep convection separated from the low-level center a
little before 0000 UTC, and now its convection is confined to a new
area about 50 n mi north and northeast of the center.  This degraded
appearance in the cyclone's structure is due to about 20 kt of
westerly vertical wind shear and dry mid-level air.  An ASCAT pass
from around 0200 UTC showed maximum winds in the 40 to 45 kt range,
but since the convective pattern has degraded since then, the
initial wind speed is lowered to 40 kt.  This estimate is also near
an average of the Dvorak FT and CI numbers from TAFB.
The westerly shear is expected to increase even more during the
next couple of days.  These hostile winds aloft combined with the
continued influence of dry and stable air should cause continued
weakening, and Melissa is forecast to degenerate to a remnant low in
about 24 hours, when it is forecast to be over SSTs below 22 C.  The
global models show the remnants of Melissa becoming absorbed or
merging with a front in 2 to 3 days.
Melissa has moved a little to the north of the previous track, with
the initial motion now estimated to be 065/12 kt.  The steering
pattern is expected to become more zonal during the next couple of
days, which should cause Melissa to move generally eastward at
increasing forward speeds before it is absorbed within the
frontal zone.  The official track forecast is adjusted a little to
the north of the previous one to account for the initial motion and
position.  This forecast lies near the middle of the tightly-packed
guidance envelope.
INIT  13/0900Z 39.3N  62.6W   40 KT  45 MPH
 12H  13/1800Z 40.2N  59.9W   35 KT  40 MPH
 24H  14/0600Z 41.1N  55.4W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  14/1800Z 42.0N  50.2W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  15/0600Z 42.3N  44.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  16/0600Z...DISSIPATED
Forecaster Cangialosi

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