[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 191456
TCDAT5

Hurricane Jerry Discussion Number   9
NWS National Hurricane Center Miami FL       AL102019
1100 AM AST Thu Sep 19 2019

Satellite images indicate that the center of Jerry is on the
northwestern side of the central dense overcast near a very deep
convective burst.  An Air Force recon plane just flew through the
center and found a central pressure of 988 mb and SFMR values near
65 kt.  These data support making Jerry the 4th hurricane of the
2019 Atlantic hurricane season with initial wind speed of 65 kt.

Jerry has the potential to further strengthen today, but an
increase in northwesterly shear related to an upper-level ridge is
anticipated overnight. This change in shear will likely arrest the
development of Jerry and start a slow weakening trend sometime
tomorrow. In 3 or 4 days, Jerry could enter a more conducive
environment for strengthening, but there is a pretty large spread in
the shear forecast near the cyclone at this time, related to the
positioning of Jerry relative to the ridge. Since the environmental
uncertainty at long range is so high, little change has been made to
the previous forecast.

The initial motion is estimated to be west-northwestward, or 295/14
kt.  The track forecast has remained rather consistent during the
past several cycles, taking Jerry just north of the Leeward
Islands during the first couple of days due to seemingly reliable
steering flow from the subtropical ridge to the north. The track
is a little trickier beyond that time due to some dependence on the
strength of Jerry, with a stronger system likely moving a
bit longer toward the west-northwest, similar to the latest
ECMWF/HWRF forecast. Regardless, the cyclone should eventually turn
northward and northeastward by day 5 due to a substantial break in
the subtropical ridge.  The track forecast puts slightly greater
weight on those stronger solutions, and the official track forecast
is a little left of the various consensus aids and not too far from
the last NHC prediction.

Key Messages:

1. Although the core of Jerry is expected to pass north of
northern Leeward Islands, tropical-storm-force winds and locally
heavy rainfall are possible, and tropical storm watches are in
effect.

FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 16.8N  54.4W   65 KT  75 MPH
 12H  20/0000Z 17.5N  56.5W   75 KT  85 MPH
 24H  20/1200Z 18.5N  59.3W   75 KT  85 MPH
 36H  21/0000Z 19.5N  62.1W   70 KT  80 MPH
 48H  21/1200Z 20.7N  64.8W   65 KT  75 MPH
 72H  22/1200Z 23.5N  68.6W   60 KT  70 MPH
 96H  23/1200Z 26.5N  70.0W   65 KT  75 MPH
120H  24/1200Z 30.5N  67.0W   65 KT  75 MPH

$$
Forecaster Blake
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