[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 120234
TCDAT4

Subtropical Storm Melissa Discussion Number   3
NWS National Hurricane Center Miami FL       AL142019
1100 PM AST Fri Oct 11 2019

Although Melissa's convection hasn't been very deep for much of the
day, there has been a slight cooling of cloud tops during the past
few hours.  This could possibly be due to the system's center now
moving over the core of the Gulf Stream current, where water
temperatures are around 27 degrees Celsius.  There has also been
sporadic lightning strikes observed within the convection to the
north of the center.  Despite this, the latest Hebert-Poteat
subtropical classification from TAFB is ST2.5/35 kt, and a UW-CIMSS
SATCON estimate from a few hours ago was 44 kt.  Based on these
data, Melissa's winds are lowered to 45 kt.

Melissa is moving a little faster and now toward the southeast, or
125/6 kt.  Although Melissa and its parent upper-level low are cut
off from the mid-latitude westerlies, a ridge currently located over
the Appalachian Mountains is expected to flatten on Saturday,
causing westerly flow to become established and force Melissa out
to sea.  The cyclone is forecast to accelerate eastward starting on
Saturday and continuing into early next week.  No significant
changes were made to the NHC track forecast on this cycle.

Melissa's journey across the warm Gulf Stream waters will be short
lived, only lasting for about 12 hours, and upper-level westerly
winds will be increasing over the system significantly on Saturday.
Therefore, gradual weakening is anticipated, with the NHC intensity
forecast more or less mirroring the guidance provided by the GFS
and ECMWF global models.  Melissa is expected to degenerate into a
remnant low by 36 hours, if not sooner.  The remnant low is likely
to be absorbed within a frontal zone over the north Atlantic by day
4.

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 the Gulf of Maine and 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 overnight and on Saturday, 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 on Saturday around times of high tide.  For more information,
see products issued by local National Weather Service forecast
offices at weather.gov.


FORECAST POSITIONS AND MAX WINDS

INIT  12/0300Z 37.7N  68.8W   45 KT  50 MPH
 12H  12/1200Z 37.8N  67.7W   40 KT  45 MPH
 24H  13/0000Z 38.1N  65.2W   35 KT  40 MPH
 36H  13/1200Z 38.5N  62.1W   30 KT  35 MPH...POST-TROP/REMNT LOW
 48H  14/0000Z 39.0N  58.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  15/0000Z 40.4N  50.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  16/0000Z...ABSORBED WITHIN A FRONTAL ZONE

$$
Forecaster Berg
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