[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 170232
TCDAT4

Hurricane Humberto Discussion Number  18
NWS National Hurricane Center Miami FL       AL092019
1100 PM EDT Mon Sep 16 2019

Humberto continues to have an impressive overall appearance on
satellite imagery, although the eye is a bit ragged looking.
Earlier radar images from the NOAA P-3 aircraft showed that the
eyewall was somewhat fragmented.  A last-minute observation of
700-mb flight-level winds of 86 kt from the Air Force Hurricane
Hunters, outbound to the west of the eye, is roughly consistent with
a current intensity estimate of 80 kt.  Humberto should continue to
traverse warm waters for the next couple of days, and much of the
numerical guidance shows intensification in the short term.
Therefore the official forecast, like the previous one, continues to
call for the system to become a major hurricane within the next
day or so.  This is similar to the intensity model consensus.  By 48
hours, the shear should become very strong and a weakening trend
will likely be underway.  By day 5, if not sooner, the ECMWF global
model shows the system embedded within a frontal zone so Humberto
is forecast to be extratropical at that time.

The eye has been wobbling over the past few hours, but a smoothed
estimate of the motion is just north of east or 075/7 kt.  Humberto
should continue to move along the northern side of a subtropical
ridge with a gradual increase in forward speed for the next couple
of days. After that, the hurricane should turn northeastward and
north-northeastward with some additional acceleration in response
to a strong mid-tropospheric trough near Atlantic Canada.  Around
the end of the forecast period, the global models differ
significantly as to how far north into the Atlantic Humberto will
move.  The official forecast leans toward the ECMWF and corrected
consensus, HCCA, guidance.

It is still too early to give a good estimate as to how close the
core of the hurricane will come to Bermuda.  Interests should not
focus on the exact forecast track; only a slight deviation to the
right could bring the center near or over the island.

Large swells from Humberto will affect Bermuda by late Tuesday, and
affect portions of the northwestern Bahamas and southeastern United
States coast during the next couple of days.  These swells are
expected to produce dangerous surf conditions and life-threatening
rip currents.  See products issued by your local weather office and
the Bermuda Weather Service for additional information.


FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 30.3N  75.1W   80 KT  90 MPH
 12H  17/1200Z 30.7N  74.0W   90 KT 105 MPH
 24H  18/0000Z 31.1N  72.2W   95 KT 110 MPH
 36H  18/1200Z 31.6N  70.0W  100 KT 115 MPH
 48H  19/0000Z 32.8N  66.6W   90 KT 105 MPH
 72H  20/0000Z 37.1N  60.7W   80 KT  90 MPH
 96H  21/0000Z 40.5N  58.0W   65 KT  75 MPH
120H  22/0000Z 43.0N  50.0W   55 KT  65 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch
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