[Tropical] Tropical Cyclone Discussion

EMWIN Server emwin at nashvilleweather.net
Sat Aug 15 03:39:46 CDT 2020


WTNT41 KNHC 150839
TCDAT1

Tropical Storm Josephine Discussion Number  15
NWS National Hurricane Center Miami FL       AL112020
500 AM AST Sat Aug 15 2020

Josephine continues to produce disorganized bursts of deep
convection to the north and northeast of the estimated center,
with little evidence of any banding features.  In spite of the
shear, the storm is still producing high-level outflow into the
strong upper-level winds.  The current intensity estimate of 40 kt
is based on continuity from the previous scatterometer-based
observations, and an ADT estimate from UW-CIMSS.  An Air Force
Hurricane Hunter aircraft is scheduled to investigate the storm
later this morning, and this should provide a good intensity
estimate.  Since vertical shear associated with a large
upper-level trough over the western Atlantic is forecast to become
quite strong over the next few days, a weakening trend is likely to
commence in a day or so.  The official forecast is similar to the
previous NHC prediction.  It is also possible that the system will
degenerate into an open wave within the next couple of days, as
shown by the global models.

It is difficult to locate the center at this time, but it is
believed to be situated near the southwest edge of the main area of
deep  convection.  This leads to a somewhat uncertain initial
motion estimate of 300/13 kt.  Josephine or its remnants are likely
to continue to move west-northwestward to the south and southwest
of a subtropical high pressure area, and then to turn northwest,
north, and north-northeast along the periphery of the high.  The
official track forecast remains close to the NOAA corrected model
consensus prediction.


KEY MESSAGES:

1. Josephine should pass far enough to the northeast of the Leeward
Islands over the weekend to prevent major impacts.  However,
interests there should continue to monitor its progress until the
storm has passed north of that area.

2. Locally heavy rainfall is possible in the northern Leeward
Islands, the Virgin Islands, and Puerto Rico as Josephine passes by
to the northeast. Isolated minor flooding is possible in Puerto
Rico through Monday.


FORECAST POSITIONS AND MAX WINDS

INIT  15/0900Z 18.9N  58.4W   40 KT  45 MPH
 12H  15/1800Z 19.6N  60.2W   40 KT  45 MPH
 24H  16/0600Z 20.7N  62.5W   40 KT  45 MPH
 36H  16/1800Z 22.0N  64.7W   35 KT  40 MPH
 48H  17/0600Z 23.4N  66.7W   30 KT  35 MPH
 60H  17/1800Z 24.9N  68.0W   30 KT  35 MPH
 72H  18/0600Z 26.5N  68.5W   25 KT  30 MPH
 96H  19/0600Z 29.0N  68.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  20/0600Z 33.0N  64.5W   20 KT  25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Pasch
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