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Tropical Storm Lorenzo Discussion Number   9
NWS National Hurricane Center Miami FL       AL132019
1100 PM AST Tue Sep 24 2019

Over the past several hours, deep convection has increased in
coverage and intensity near Lorenzo's center, with cloud tops now as
cold as -85 degrees Celsius. Some modest northwesterly shear
impacted the cyclone starting early today and lasted through this
evening, but now Lorenzo seems to be overcoming the shear. The
initial intensity has been increased to 60 kt and this is a blend of
the latest subjective Dvorak estimates from TAFB and SAB. Recent
scatterometer passes show that the wind radii have continued to
expand, with tropical storm force winds now reaching up to 180 n mi
from the center.

Lorenzo is moving west-northwestward at 14 kt to the south of a
mid-level ridge. A break in the ridge is forecast to develop between
40-50W in a few days, which should cause the cyclone to turn to the
northwest. By late in the forecast period, Lorenzo will turn to the
north as it rounds the western periphery of the ridge. This forecast
track scenario is in very good agreement with the numerical models,
and little change was made from the previous official forecast.

The shear that has been occurring over Lorenzo is expected to
decrease through Wednesday, and based on the current convective
trend, strengthening appears likely over the next couple of days.
Dynamical and statistical models are in good agreement on bringing
Lorenzo to hurricane intensity by Wednesday morning, and then
continuing some gradual strengthening through 72 hours. After that
time, the dynamical model intensity forecasts diverge from the
statistical model forecasts. SHIPS and LGEM suggest that Lorenzo
will reach its peak intensity in about 3 or 4 days, and weakening is
possible by day 5. The dynamical models disagree with this scenario,
and the consensus of those models makes Lorenzo a major hurricane in
about 72 hours, with additional strengthening possible through the
end of the forecast period. The official forecast is more in line
with the dynamical guidance, although it is not as high as some of
those solutions late in the period. Due to the divergence in model
intensity forecasts beyond 72 hours, the confidence in the official
forecast at that time is not high.

FORECAST POSITIONS AND MAX WINDS

INIT  25/0300Z 13.2N  32.4W   60 KT  70 MPH
 12H  25/1200Z 13.6N  34.4W   70 KT  80 MPH
 24H  26/0000Z 14.2N  37.0W   80 KT  90 MPH
 36H  26/1200Z 15.1N  39.1W   90 KT 105 MPH
 48H  27/0000Z 16.4N  40.9W   95 KT 110 MPH
 72H  28/0000Z 19.9N  43.6W  100 KT 115 MPH
 96H  29/0000Z 23.0N  45.5W  105 KT 120 MPH
120H  30/0000Z 26.0N  45.0W  105 KT 120 MPH

$$
Forecaster Latto

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