[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 302051
TCDAT4

HURRICANE MATTHEW DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
500 PM EDT FRI SEP 30 2016

Matthew has continued to rapidly strengthen at a remarkable rate
today.  A NOAA Hurricane Hunter aircraft recently reported a peak
SFMR wind of 116 kt and flight-level winds of 121 kt.  A recent
dropsonde from the aircraft indicated that surface winds are around
120 kt.  Based on all of these data, the initial intensity is set to
120 kt, an increase of 55 kt in the last 24 hours.  The latest
pressure estimate from the aircraft is 949 mb, a drop of 44 mb since
this time yesterday.

Some additional strengthening is possible in the next 12 hours or
so, and the NHC forecast reflects that possibility, showing 125 kt
at that time.  Given the lack of skill of the intensity guidance
thus far, this remains a low confidence forecast, and its possible
this could be conservative.  Since Matthew has now become a major
hurricane, eyewall replacement cycles could occur that would lead to
some fluctuations in intensity not shown here.  After 12 hours, a
gradual weakening is shown, following the trend of, but above nearly
all of the intensity guidance.  Land interaction with Cuba should
lead to additional weakening by day 4, but Matthew is expected to
remain a strong hurricane through the forecast period.

The initial motion is still toward the west-southwest, but the
forward speed has slowed a bit, to around 8 kt.  The track forecast
reasoning has not changed, with Matthew expected to turn westward by
12 hours and then gradually turn toward the north in the next 3 to 4
days as the cyclone moves into a weakness in the subtropical ridge.
The track model guidance is in slightly better agreement this cycle
through 3 days, although the ECMWF remains right of and slower than
the rest of the guidance at days 4 and 5.  The GFS, HWRF, and
COAMPS-TC are faster and to the left late in the period, although
the GFS has trended slower this cycle.  The new NHC track has again
been adjusted a little to the left through 72 hours given the
initial position and motion, and after that time is along the
previous official forecast but slower, following the slower trend in
the guidance this cycle.  The NHC forecast is near the middle of the
guidance envelope and is a little to the east of the multi-model
consensus at days 4 and 5.

It is important to remind users that average NHC track forecast
errors are around 175 miles at day 4 and 230 miles at day 5.
Therefore, it is too soon to rule out possible hurricane impacts
from Matthew in Florida.

FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z 13.5N  71.6W  120 KT 140 MPH
 12H  01/0600Z 13.3N  72.8W  125 KT 145 MPH
 24H  01/1800Z 13.5N  73.9W  120 KT 140 MPH
 36H  02/0600Z 14.1N  74.8W  115 KT 130 MPH
 48H  02/1800Z 15.2N  75.6W  110 KT 125 MPH
 72H  03/1800Z 18.2N  76.2W  105 KT 120 MPH
 96H  04/1800Z 22.0N  76.0W   90 KT 105 MPH
120H  05/1800Z 25.0N  76.0W   90 KT 105 MPH

$$
Forecaster Brennan

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