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HURRICANE MARTY DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP172015
400 PM CDT MON SEP 28 2015

Air Force Reserve Hurricane Hunter data was very helpful with both
the positioning and intensity of Marty this afternoon.  The data
show that Marty has become a hurricane, with SFMR winds of 70 kt
observed, which will be used as the initial wind speed.

The aircraft fix position was about 30 n mi to the northeast of my
previous estimate.  Consequently, based on the aircraft fix data and
a longer-term motion -- Marty appears to be moving northeastward at
about 5 kt.  Guidance has all shifted northeastward, with the
hurricane likely to move very near the coast of Mexico on Tuesday,
and a number of models move the cyclone inland.  While the consensus
is still offshore, the official forecast follows the trend of the
guidance by bringing Marty within 20 n mi of the coast. This change
necessitates a Hurricane Warning for the coast of south-central
Mexico.  If the cyclone survives land interaction with the high
terrain, a ridge is forecast to build over Mexico, which should
cause Marty to move westward or west-northwestward after 48 hours.

Increasing vertical wind shear is expected to cause a gradual
weakening of Marty by Tuesday. This trend should then continue
throughout the remainder of the forecast period while Marty remains
in an area of moderate or strong southwesterly shear, and
potentially interacts with land.  Most of the guidance, except the
ECMWF, continues to shows the cyclone dissipating by day 5 due to
the strong shear. The forecast intensity is raised in the short term
due to the initial increase in wind speed, then is blended with the
intensity consensus at long range.  It is possible that Marty could
weaken a lot faster than shown below if it gets closer to Mexico.

FORECAST POSITIONS AND MAX WINDS

INIT  28/2100Z 16.7N 102.1W   70 KT  80 MPH
 12H  29/0600Z 16.8N 101.8W   70 KT  80 MPH
 24H  29/1800Z 17.1N 101.6W   65 KT  75 MPH
 36H  30/0600Z 17.3N 101.8W   50 KT  60 MPH
 48H  30/1800Z 17.5N 102.5W   45 KT  50 MPH
 72H  01/1800Z 17.8N 105.0W   35 KT  40 MPH
 96H  02/1800Z 18.0N 106.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  03/1800Z...DISSIPATED

$$
Forecaster Blake

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