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Tropical Storm Humberto Discussion Number  10
NWS National Hurricane Center Miami FL       AL092019
1100 PM EDT Sat Sep 14 2019

Humberto is gradually strengthening.  Both the NOAA and Air Force
Hurricane Hunters have been investigating the storm this evening and
they have found that the cyclone is a little stronger.  Based on
that data, the initial wind speed is nudged upward to 50 kt and the
minimum pressure is around 1000 mb.  Satellite images also show
that the storm's structure is improving with an inner core trying to
form and banding features becoming better defined to the north of
the center.  Doppler radar data from the NOAA P-3 aircraft indicate
that the cyclone has become less titled in the vertical, suggesting
that the shear has lessened over the system.  However, there is
still some signs of dry air being wrapped into the southern side of
the circulation.

Satellite and aircraft fixes indicate that the storm is moving
north-northwestward at about 5 kt, steered by a mid-level ridge to
its north-northeast over the western Atlantic.  Humberto is expected
to slow down and turn northward on Sunday well off the coast of
east-central Florida as it moves into a developing weakness in the
ridge. After that time, a turn to the northeast and then the
east-northeast with a gradual increase in forward speed is predicted
as Humberto moves along with the flow near the base of a large scale
trough.  The track models are in relatively good agreement, and only
small changes were made to the previous forecast.

The tropical storm is likely to continue strengthening during the
next 3 to 4 days as it remains in relatively low wind shear
conditions and over the warm Gulf Stream waters.  Beyond that time,
an increase in wind shear associated with an approaching shortwave
trough will likely cause some weakening.  The NHC intensity forecast
is slightly higher than the previous one and shows Humberto becoming
a hurricane in about 24 hours with additional strengthening
thereafter. This forecast is in best agreement with the intensity
consensus models HCCA, IVDR, and IVCN.

The global models suggest that as Humberto gains latitude and
intensifies, its wind field will gradually expand, and that
is reflected in the NHC wind radii forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  15/0300Z 27.6N  77.3W   50 KT  60 MPH
 12H  15/1200Z 28.5N  77.8W   60 KT  70 MPH
 24H  16/0000Z 29.3N  77.8W   65 KT  75 MPH
 36H  16/1200Z 29.9N  77.1W   70 KT  80 MPH
 48H  17/0000Z 30.4N  75.8W   75 KT  85 MPH
 72H  18/0000Z 31.2N  72.0W   90 KT 105 MPH
 96H  19/0000Z 33.0N  65.6W   95 KT 110 MPH
120H  20/0000Z 36.9N  58.9W   75 KT  85 MPH

$$
Forecaster Cangialosi

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