[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 180256
TCDAT4

Hurricane Humberto Discussion Number  22
NWS National Hurricane Center Miami FL       AL092019
1100 PM EDT Tue Sep 17 2019

Humberto has an impressive presentation on satellite images, with a
large 30-40 n mi diameter eye surrounded by very cold cloud tops.
An Air Force Reserve Unit Hurricane Hunter aircraft investigating
the hurricane found SFMR-observed surface winds of 98 kt and peak
700-mb flight-level winds of 111 kt.  Based on these observations,
the current intensity was set at 100 kt, which made the system a
major hurricane.  Some fluctuations in strength due to a potential
eyewall replacement are possible during the next 24 hours or so, but
strong southwesterly shear should result in a weakening trend to
commence on Thursday.  In 72 hours, the global models show the
system merging with a frontal zone so the NHC forecast calls for
extratropical transition by that time.  The official intensity
forecast follows the model consensus.

Center fixes from the Hurricane Hunters indicate that the motion
continues to be east-northeastward or 075/10 kt.  Humberto is
likely to turn toward the northeast and north-northeast at a faster
forward speed in 24-36 hours as it interacts with a strong mid-level
trough at mid-latitudes to its north and northeast.  Later in the
forecast period, the track guidance indicates that Humberto will
turn back toward the east-northeast as it moves in tandem with the
mid-latitude trough over the north Atlantic.  The official forecast
is in close agreement with the simple and corrected consensus
models, TVCA and HCCA.


Key Messages:

1. Hurricane conditions are expected in Bermuda Wednesday night and
Thursday morning, with tropical-storm-force winds expected by
Wednesday afternoon. Residents there should follow advice given by
local officials.

2.  Storm surge and dangerous breaking waves could cause coastal
flooding Wednesday night and Thursday along the southern coast of
Bermuda.

3. Swells will continue to affect the northwestern Bahamas and the
southeastern coast of the United States from east-central Florida to
North Carolina during the next couple of days, creating life-
threatening surf and rip current conditions.


FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 31.3N  71.0W  100 KT 115 MPH
 12H  18/1200Z 32.0N  68.9W  100 KT 115 MPH
 24H  19/0000Z 33.4N  65.5W  100 KT 115 MPH
 36H  19/1200Z 36.0N  62.0W   90 KT 105 MPH
 48H  20/0000Z 38.6N  60.2W   75 KT  85 MPH
 72H  21/0000Z 42.5N  56.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
 96H  22/0000Z 44.0N  44.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  23/0000Z 49.0N  26.0W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Pasch
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