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Hurricane Jerry Discussion Number  12
NWS National Hurricane Center Miami FL       AL102019
500 AM AST Fri Sep 20 2019

Jerry appears to have stopped strengthening for now.  The last
reports from the Air Force Hurricane Hunters indicated that the
minimum pressure had risen slightly, and the satellite appearance
has become a little more ragged during the past several hours.
Radar images sent from the aircraft showed a well-defined inner
core, but there are no hints of an eye in geostationary satellite
images.  The initial intensity is held at 90 kt based on the earlier
aircraft data.  Both the Air Force and NOAA Hurricane Hunters will
be investigating Jerry later today, and that data should provide a
better assessment of its intensity and structure.

Jerry continues to move west-northwestward at a relatively quick
pace of 14 kt.  This motion is expected to continue for about
another 24 hours as the cyclone is steered by a subtropical ridge to
its northeast.  The ridge is expected to weaken and slide eastward
late this weekend in response to an eastward-moving trough over the
north Atlantic.  This change in the steering pattern should cause
Jerry to slow down and gradually turn to the northwest and then the
north late this weekend and early next week.  A faster north-
northeastward motion is anticipated toward the end of the forecast
period as another trough approaches the system.  The models remain
in very good agreement on the hurricane passing well to the north of
the northern Leeward Island and Puerto Rico late today and Saturday
and possibly moving near Bermuda in a little more than 4 days.
The only notable change this cycle is a slower northward motion from
days 3 to 5 to be in better agreement with the latest models.

The intensity forecast is a bit more challenging.  The global models
show a relatively favorable upper-level wind pattern over Jerry
during the next couple of days, but there is also a significant
amount of dry air around the cyclone.  Although the shear could
increase early next week, some of the models show Jerry deepening,
likely due to baroclinic effects due to the nearby trough. There is
a very large spread in the intensity guidance ranging from SHIPS and
LGEM showing little change in strength to pronounced weakening shown
by HMON during the forecast period.  The NHC intensity forecast is
between those extremes and lies a little above the consensus aids.

Key Messages:

1. Although the core of Jerry is expected to move north of the
northern Leeward Islands, heavy rainfall and flash floods are
possible there today.

FORECAST POSITIONS AND MAX WINDS

INIT  20/0900Z 18.4N  58.7W   90 KT 105 MPH
 12H  20/1800Z 19.1N  60.8W   85 KT 100 MPH
 24H  21/0600Z 20.4N  63.3W   80 KT  90 MPH
 36H  21/1800Z 21.8N  65.4W   75 KT  85 MPH
 48H  22/0600Z 23.2N  67.1W   70 KT  80 MPH
 72H  23/0600Z 26.1N  68.4W   65 KT  75 MPH
 96H  24/0600Z 29.4N  66.8W   65 KT  75 MPH
120H  25/0600Z 34.6N  63.0W   65 KT  75 MPH

$$
Forecaster Cangialosi

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