[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 021456
TCDAT4

HURRICANE MATTHEW DISCUSSION NUMBER  18
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016
1100 AM EDT SUN OCT 02 2016

The eye of Matthew has become obscured on visible satellite images,
which is often an indication of weakening.  Microwave images showed
a distinct dry slot over the southwestern and western portions of
the circulation.  Also there has been a persistent, but
inexplicable, cluster of deep convection located a couple of degrees
to the east of the hurricane and the effect of this feature on
Matthew's intensity evolution is unknown.  An Air Force Hurricane
Hunter aircraft investigated the northeastern eyewall, the strongest
part of the circulation, and found that the winds had decreased
somewhat from earlier this morning.  The intensity is set to 120 kt
for this advisory.  The vertical shear is not forecast to become
much stronger while Matthew is in the Caribbean, so the hurricane
should remain near category 4 status for the next 36-48 hours.  Once
Matthew moves into the Atlantic, some increase in shear along with
a decrease in oceanic heat content should result in a little
weakening.  However, there is significant uncertainty in the 3-5 day
forecast intensities.

After a northwestward motion, the center has meandered westward
over the past few hours.  Matthew is expected to turn northward and
move between a mid-level ridge to the east and a weak trough over
the Gulf of Mexico for the next few days.  Later in the forecast
period, the global models show a slight building of a ridge to the
northeast of Matthew which would induce a turn toward the left in
3-5 days.  The timing and magnitude of this turn is still uncertain
however.  Looking at the better-performing models, the track
guidance suite is bracketed by the GFS model on the left and the
HWRF model on the right.  The official forecast is slightly west of
the multi-model consensus and very similar to the previous NHC
track.

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  02/1500Z 14.0N  74.6W  120 KT 140 MPH
 12H  03/0000Z 14.9N  74.8W  120 KT 140 MPH
 24H  03/1200Z 16.1N  75.0W  115 KT 130 MPH
 36H  04/0000Z 17.7N  74.7W  115 KT 130 MPH
 48H  04/1200Z 19.5N  74.5W  110 KT 125 MPH
 72H  05/1200Z 23.2N  75.0W  100 KT 115 MPH
 96H  06/1200Z 26.5N  76.0W   95 KT 110 MPH
120H  07/1200Z 29.5N  76.5W   90 KT 105 MPH

$$
Forecaster Pasch
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