[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 030851
TCDAT4

HURRICANE MATTHEW DISCUSSION NUMBER  21
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
500 AM EDT MON OCT 03 2016

The Air Force Reserve reconnaissance mission that ended shortly
before 0600 UTC did not find flight-level or surface winds as high
as reported during the previous flight yesterday afternoon.  It is
not clear from microwave imagery if the reduction in winds is the
result of an eyewall replacement.  There was no evidence of a double
wind maximum in the aircraft data, but the crew reported that the
eyewall was open to the southwest.  Using a blend of the aircraft
data and recent satellite intensity estimates, the initial intensity
has been reduced to 115 kt for this advisory.  The center of Matthew
has recently passed over NOAA buoy 42058 in the central Caribbean
Sea, which reported a minimum pressure of 943 mb and light winds
around 0650 UTC.

Satellite and aircraft fixes show that Matthew is moving northward
or 360/5 kt.  The hurricane is expected to move generally northward
around the western periphery of a subtropical ridge over the
west-central Atlantic during the next couple of days, and little
change was needed to the NHC forecast through 48 hours.   Once
Matthew moves near the southeastern Bahamas on Wednesday, it is
forecast to turn northwestward or north-northwestward in
southeasterly flow between the ridge and a mid- to upper-level
low/trough over the southeastern Gulf of Mexico and northwestern
Caribbean Sea.  The model guidance is in relatively good agreement
through 72 hours, but begin to diverge by days 4 and 5.  The UKMET
which was previously the western outlier, has shifted eastward this
cycle, and is now close to the GFS.  The 0000 UTC ECMWF trended
westward and that model is now along the western edge of the
guidance envelope.  The NHC track has been nudged westward at days
4 and 5, and lies close to the GFS and UKMET solutions.  This is a
bit west of the model consensus since the higher quality models
are on that side of the guidance envelope.

Matthew is forecast to remain in low shear and over warm water
while it moves northward toward the Greater Antilles.  Some
restrengthening is possible, but fluctuations in intensity are
likely due to eyewall cycles that are difficult to predict. Some
weakening is forecast when the hurricane interacts with land in a
couple of days, however Matthew is expected to remain a powerful
hurricane throughout much of the forecast period.

Although the official forecast continues to show a track east of
Florida, it is still too soon to rule out possible hurricane
impacts there.  It is also too soon to know whether, or how, Matthew
might affect the remainder of the United States east coast.


FORECAST POSITIONS AND MAX WINDS

INIT  03/0900Z 15.2N  74.9W  115 KT 130 MPH
 12H  03/1800Z 16.2N  74.9W  115 KT 130 MPH
 24H  04/0600Z 17.9N  74.7W  115 KT 130 MPH
 36H  04/1800Z 19.7N  74.6W  115 KT 130 MPH
 48H  05/0600Z 21.4N  74.8W  105 KT 120 MPH
 72H  06/0600Z 24.6N  75.9W  105 KT 120 MPH
 96H  07/0600Z 27.6N  76.9W   95 KT 110 MPH
120H  08/0600Z 30.8N  77.0W   90 KT 105 MPH

$$
Forecaster Brown
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